Mitral stenosis: Preconception and pregnancy care

INTRODUCTION — 

Mitral stenosis (MS) encountered in individuals of childbearing age is nearly always rheumatic in origin. Maternal and perinatal complications during pregnancy in individuals with MS reflect the unfavorable interaction between physiologic cardiovascular changes of pregnancy and the stenotic mitral valve. (See "Maternal adaptations to pregnancy: Cardiovascular and hemodynamic changes".)

This topic will review the evaluation and management for patients with MS prior to and during pregnancy.

Management of other types of heart disease during pregnancy, including those with MS who have undergone valve replacement, is discussed separately:

●(See "Pregnancy and valve disease".)

●(See "Management of risks of prosthetic valves during pregnancy" and "Management of antithrombotic therapy for a prosthetic heart valve during pregnancy".)

●(See "Acquired heart disease and pregnancy".)

●(See "Pregnancy in women with congenital heart disease: General principles" and "Pregnancy in patients with congenital heart disease: Specific lesions" and "Pulmonary hypertension with congenital heart disease: Pregnancy and contraception".)

MITRAL STENOSIS PREVALENCE — 

Individuals with heart disease compose approximately 1 percent of the obstetric population seen in large volume centers in resource-abundant countries. In the United States and Canada, individuals with rheumatic heart disease, of which MS is the most common manifestation, compose <25 percent of pregnant patients with heart disease [1,2].

In contrast, MS is a common condition among pregnant individuals with heart disease in regions of the world where rheumatic heart disease is prevalent. For example, rheumatic heart disease was the underlying cause of heart disease in 56 to 92 percent of 1875 pregnant patients with heart disease in four studies from centers from Brazil, Turkey, Senegal, and India [3-6]. (See "Clinical manifestations and diagnosis of rheumatic heart disease", section on 'Mitral stenosis'.)

RISK ASSOCIATED WITH MITRAL STENOSIS

Maternal risk — Pregnant patients with MS are at risk for complications including heart failure, atrial arrhythmias, and thromboembolic events (table 1). Maternal mortality has been reported and is higher in resource-limited settings. (See 'Global variation in risk' below.)

Stratification of maternal risk is discussed below. (See 'Risk stratification' below.)

Risk of heart failure — In MS, the stenotic mitral valve restricts diastolic left ventricular filling, resulting in elevations in transmitral gradient and left atrial pressure that are further increased by the physiologic hypervolemia and increased heart rate associated with pregnancy, thereby increasing the risk of pulmonary edema (figure 1). (See "Pathophysiology and natural history of mitral stenosis" and "Maternal adaptations to pregnancy: Cardiovascular and hemodynamic changes".)

In two series from the Registry of Pregnancy and Cardiac Disease (ROPAC) and India, up to 91 percent of heart failure episodes first occurred in the antepartum period and up to 29 percent occurred during delivery or the first postpartum week [6,7]. This observation parallels the finding of a prospective Canadian study of pregnant patients with a wide spectrum of heart disease, in which there were two peaks of incidence of heart failure in the third trimester (28 to 40 weeks gestation) and in the first postpartum week, corresponding to the peak hemodynamic load during the late antepartum period and the time of postpartum fluid redistribution [8]. Redistribution pulmonary edema may result from postdelivery autotransfusion of venous return from the lower extremities when the emptied uterus no longer impedes venous return. Management of this risk is discussed below. (See 'Medical management of heart failure' below and 'Postpartum care' below.)

Even when pregnancy is not complicated by the development of pulmonary edema, some patients with MS experience deterioration in their functional class or develop new cardiac symptoms. In two North American series of pregnancies in patients with MS (total of 126 pregnancies), 74 and 40 percent of patients experienced deterioration of one and two New York Heart Association (NYHA) functional classes, respectively, as their pregnancies progressed [9,10]. If not promptly diagnosed and treated, patients who deteriorate to NYHA class III or IV will likely progress to frank pulmonary edema.

While patients with rheumatic heart disease with predominant mitral regurgitation (MR) are commonly viewed as being at lower risk than those with predominant MS, a 15 percent rate of heart failure has been reported in those with rheumatic moderate or severe MR [7]. For prediction of maternal cardiac risk, moderate to severe MR is considered equivalent to MS with mitral valve area <2.0 cm² [8]. (See "Pregnancy and valve disease", section on 'Mitral regurgitation'.)

Risk of atrial arrhythmias and thromboembolism — The risk of supraventricular arrhythmias increases during pregnancy, which in turn can precipitate pulmonary edema. Although atrial fibrillation (AF) is the most common arrhythmia encountered, other supraventricular arrhythmias can be manifested, including atrial flutter and supraventricular tachycardia. Increased left atrial pressure and increased atrial irritability increase the risk of AF, which may precipitate pulmonary edema. Pulmonary congestion and AF can become a self-perpetuating vicious cycle, and it is not always clear which was the precipitating factor.

In contrast to heart failure, which peaks in the third trimester and the postpartum period, cardiac arrhythmia can occur anytime in the ante-, peri-, or postpartum period [8]. In one series, 20 percent of the pulmonary edema episodes occurred in the setting of atrial tachyarrhythmias [10]. (See "Supraventricular arrhythmias during pregnancy".)

AF combined with the hypercoagulability associated with pregnancy increases the risk of left atrial thrombus formation and thromboembolism. Only one stroke was reported in the above-cited North American and European series of pregnancy in patients with heart disease including MS [5,9-11], perhaps due to increased vigilance and prompt initiation of anticoagulation. In the above-cited series from Brazil, eight episodes of thromboembolism occurred in 448 patients with native mitral valves [3].

Fetal and neonatal risk — The risk of perinatal complications, including premature labor, low birth weight, premature delivery, and perinatal death, are increased in pregnancies in patients with MS and are more frequent with increasing severity of MS (table 1) [7,9,10,12]. In the presence of obstetric risk factors (including extremes of maternal age, smoking), the presence of maternal MS confers additional risk of perinatal complications [13].

ROLE OF PREGNANCY HEART TEAM — 

Since individuals with MS are at risk of complications during and following pregnancy, they should be provided specialized evaluation, counseling, and management by a multidisciplinary pregnancy heart team prior to, during, and following pregnancy, including delivery and the postpartum period [14-17]. The pregnancy heart team should include, at a minimum, a cardiologist with expertise in management of pregnancy in patients with heart disease and an obstetrician with expertise in maternal-fetal medicine to enable expert assessment and management of cardiovascular, obstetric, and perinatal risk. The team should also include an interventional cardiologist, cardiovascular surgeon, and anesthesiologist if mitral valve intervention might be indicated prior to or during pregnancy.

PRECONCEPTION CARE

Timing — Preconception care for individuals with MS who are contemplating pregnancy includes assessment of maternal, fetal, and neonatal risk and counseling by a multidisciplinary pregnancy heart team. If a pregnant patient with MS has not received preconception evaluation and counseling, an assessment of risk and counseling should be provided by the pregnancy heart team as soon as the patient presents for care. (See 'Role of pregnancy heart team' above and "The prepregnancy office visit".)

Counseling — Prepregnancy counseling by a pregnancy heart team is an essential component of care for females of child-bearing potential who have MS. For those individuals who do not present until they are pregnant, counseling should be performed as early in pregnancy as possible. The purposes of prepregnancy or pregnancy counseling are to provide risk assessment and discuss management to reduce risk and mitigate effects of potential complications (table 2). Counseling includes discussion of indications for preconception intervention to reduce maternal and fetal risks. (See 'Preconception intervention' below.)

If a patient with very severe MS (mitral valve area [MVA] <1 cm²) presents early in pregnancy, the decision on whether to terminate the pregnancy is individualized based upon the patient's preference with consideration of access to care, functional status, and other pregnancy risk factors.

Patients who are receiving anticoagulant therapy (eg, for AF) should have the opportunity to make an informed decision about the various options for anticoagulation so that the anticoagulation plan can be implemented once pregnancy is confirmed. (See "Anticoagulation during pregnancy and postpartum: Agent selection and dosing" and "Prenatal care: Initial assessment" and "Management of antithrombotic therapy for a prosthetic heart valve during pregnancy".)

Preconception counseling should include discussion of avoidance of exposures (such as alcohol consumption and smoking) and medications (eg, angiotensin converting enzyme inhibitors and angiotensin II receptor blockers) that pose risks during pregnancy, as discussed separately. (See "The prepregnancy office visit" and "Adverse effects of angiotensin-converting enzyme inhibitors and receptor blockers in pregnancy".)

While data are not available for patients with MS, patients considering assisted reproductive technology to achieve conception should be aware of the risks of maternal cardiac and neonatal complications associated with these procedures [18]. (See "Assisted reproductive technology: Pregnancy and maternal outcomes" and "Assisted reproductive technology: Infant and child outcomes".)

Evaluation

Routine evaluation — A careful cardiac history and physical examination, 12-lead electrocardiogram (ECG), and comprehensive transthoracic echocardiogram will generally provide the information necessary for the management of the patient with MS who is pregnant or contemplating pregnancy. Echocardiography is a key test for staging MS (table 3) and also enables assessment of any concomitant mitral regurgitation (MR) or other valve lesions. (See "Rheumatic mitral stenosis: Clinical manifestations and diagnosis", section on 'Diagnosis and evaluation'.)

Additional tests — Exercise testing (including cardiopulmonary or exercise echocardiography) is useful to assess objective exercise tolerance, the mean mitral valve gradient and pulmonary artery pressure during exercise. Exercise testing is helpful for selected patients with severe MS with uncertain functional status as well as for selected patients with symptoms on exertion and resting hemodynamics consistent with nonsevere (progressive) MS (MVA >1.5 cm²).

Elevations in pulmonary artery wedge pressure (>25 mmHg) on exercise testing during cardiac catheterization or mean mitral valve gradient (>15 mmHg) on exercise echocardiography (or cardiac catheterization) are used to identify patients likely to benefit from intervention with percutaneous mitral balloon commissurotomy (PMBC). (See 'Preconception intervention' below.)

If noninvasive data are discordant, invasive hemodynamic evaluation is an option [19]. (See "Rheumatic mitral stenosis: Clinical manifestations and diagnosis", section on 'Diagnosis and evaluation'.)

Stages of MS — MS is staged based on integration of information generally obtained from echocardiography (valve anatomy, valve hemodynamics, secondary hemodynamic effects), and patient symptoms (table 3) [20,21]. Criteria for severe MS include MVA ≤1.5 cm². Very severe MS is a subset of severe MS identified by MVA <1.0 cm². (See "Rheumatic mitral stenosis: Clinical manifestations and diagnosis", section on 'Echocardiography' and "Rheumatic mitral stenosis: Clinical manifestations and diagnosis", section on 'Staging'.)

Of note, the above-described staging system for MS differs from earlier staging systems used in many outcomes studies of pregnancies in patients with MS. In this topic, the discussion of these data has been adjusted to reflect the current staging system (table 3).

Risk stratification

Risk scores — Stratification of maternal risk in a patient with MS can be performed using one of the following scores. (See "Acquired heart disease and pregnancy", section on 'Predictors of cardiac events'.)

●Canadian Cardiac Disease in Pregnancy II (CARPREG II) risk score – The CARPREG II risk score includes 10 predictors of risk for the development of maternal cardiac complications and was developed on data from 1938 pregnancies in patients with congenital or acquired heart disease [8].

•Five general predictors – Prior cardiac events or arrhythmias (3 points), poor functional class or cyanosis (3 points), high risk valve disease or left ventricular outflow tract obstruction (2 points), systemic ventricular dysfunction defined as an ejection fraction less than 55 percent (2 points), and no prior cardiac intervention (1 point).

High-risk valve disease includes MVA <2 cm² (which includes severe MS [MVA ≤1.5 cm²] as well as some progressive MS (table 3)).

•Four lesion-specific predictors – Mechanical valves (3 points), high-risk aortopathy with aortic dimension >45 mm (2 points), pulmonary hypertension (2 points), and coronary artery disease (2 points).

For this score, pulmonary hypertension is defined as right ventricular systolic pressure >50 mmHg in the absence of right ventricular outflow obstruction.

•One delivery of care predictor – Late pregnancy assessment (first antenatal visit after 20 weeks gestation) (1 point).

•Estimated risk – The risk of a primary cardiac event (primarily arrhythmias and heart failure) was 5 percent for 0 to 1 point, 10 percent for 2 points, 15 percent for 3 points, 22 percent for 4 points, and 41 percent for >4 points.

●The modified World Health Organization (WHO) classification system – This is the risk stratification system in the 2018 European Society of Cardiology (ESC) guidelines for management of cardiovascular diseases during pregnancy [15]. This system was developed in resource-abundant countries and is likely most appropriate in similar settings. This classification includes valvular heart disease, arrhythmias, ventricular dysfunction, and most types of congenital heart disease. (See "Acquired heart disease and pregnancy", section on 'Predictors of cardiac events'.)

•Class I conditions are associated with no detectable increased risk of maternal mortality and no/mild increase in morbidity.

•Class II conditions are associated with small increased risk of maternal mortality or moderate increase in morbidity.

•Class II to III conditions are associated with intermediate increased risk of maternal mortality or moderate to severe increase in mortality. This category includes some progressive MS.

•Class III conditions are associated with significantly increased risk of maternal mortality or severe morbidity. This class includes severe MS (MVA ≤1.5 cm²). While the modified WHO table lists "moderate mitral stenosis" as a class III condition, in current American College of Cardiology/American Heart Association (ACC/AHA) and ESC valve guidelines, MS that was previously considered "moderate" is now staged as severe MS.

•Class IV conditions are associated with extremely high risk of maternal mortality or severe morbidity; pregnancy is considered contraindicated. Conditions in this category includes very severe MS (MVA <1.0 cm²). While the modified WHO table lists "severe mitral stenosis" as a class IV condition, in current ACC/AHA and ESC valve guidelines, MS that was previously considered "severe" is now staged as very severe MS.

●The DEVI score – This risk score was developed and validated in a single-center middle-income setting with high prevalence of rheumatic heart disease to stratify risk for pregnancy in patients with valvular heart disease [6,22]. The risk factors in the score include:

•Prior cardiovascular event (4 points)

•Pulmonary hypertension (4 points)

•Severe mitral stenosis (4 points)

•Prosthetic heart valve (2 points)

•Moderate mitral stenosis (2 points)

•Mild mitral stenosis (1 point)

•Taking cardiac medications (-1 point)

A score of ≥5 is associated with high risk of adverse cardiovascular events.

A study of 577 pregnancies in patients with valvular heart disease in a middle-income setting found that the DEVI and CARPREG-II scores showed good discriminative ability for adverse cardiac events, with the DEVI score showing better agreement with between predicted probabilities and observed events [22].

Risk factors — Regardless of the risk prediction tool chosen (see 'Risk scores' above), risk can be upgraded or downgraded based on the clinician's assessment of adherence, access, and other test results, including exercise test results [16].

The risk of maternal and fetal complications in patients with MS is related to the severity of MS, functional status, prior cardiac complications, and other markers of cardiovascular disease. Thus, risk stratification for patients with MS who are contemplating pregnancy includes identification of any markers of increased maternal cardiac risk, including [1,8-11,23]:

●Stage of MS (particularly severe MS defined as MVA ≤1.5 cm²) and severity of concurrent MR, if present. There is an incremental increase in the frequency of maternal and fetal complications with increasing severity of MS (table 1).

However, there is still a risk of heart failure, arrhythmia, and fetal complications with progressive MS (MVA >1.5 cm²) (table 1) [6,7,9,10]. This risk reflects the effects of the 30 to 50 percent increase in cardiac output during pregnancy in the setting of a mildly or moderately stenotic mitral valve [1].

●Impaired functional status by subjective (ie, New York Heart Association functional class (table 4), particularly class III or IV) or objective measures (exercise testing).

●History of pulmonary edema, arrhythmias requiring treatment, transient ischemic attack, or stroke prior to pregnancy.

●Central cyanosis (oxygen saturation <90 percent by oximetry).

●Left ventricular systolic dysfunction.

●Elevated pulmonary artery systolic pressure (PASP >50 mmHg) at baseline or during pregnancy.

The risk of adverse maternal outcomes was illustrated by a report of 56 pregnancies in 47 patients with MS enrolled in the CARPREG study. Baseline and third trimester echocardiographic parameters were associated with maternal risk [23]. Pregnancies in patients with MS with mean mitral gradient >10 mmHg or pulmonary hypertension (right ventricular systolic pressure >40 mmHg) on the baseline or third trimester echocardiogram were at the highest risk (78 percent) for maternal cardiac event (death, heart failure, tachyarrhythmia, or stroke). In contrast, maternal cardiac events occurred in 11 percent of pregnancies in patients with mean mitral gradient <10 mmHg and right ventricular systolic pressure <40 mmHg in these echocardiograms.

Obstetric complications such as pregnancy-induced hypertension and antepartum hemorrhage have been reported in patients with MS but do not seem to be related to the severity of MS [1,7,10].

Global variation in risk — Risk associated with pregnancy in patients with MS varies among countries, which may reflect social determinants of health (conditions that influence health outcomes, including economic factors, education, environmental conditions, and social and community conditions) and health care access and quality. Adverse maternal outcomes, including maternal mortality, are higher in resource-limited countries, likely related to delayed diagnosis and limited access to care [14]. A single-center study from Sub-Saharan Africa reported a maternal mortality rate of 32 percent in pregnant individuals with MS [4]. More contemporary studies mostly from resource-limited countries, including 661 pregnancies in patients with MS, reported 11 deaths in patients with severe MS (6 percent) [6,7]. In the four largest contemporary series from North America and Europe of pregnant individuals with MS (total of 300 pregnancies), there were no maternal deaths [5,9-11].

Preconception intervention — Patients with rheumatic MS with a standard indication for mitral valve intervention for severe MS (algorithm 1) or nonsevere MS (algorithm 2) should delay conception until after the intervention [20,24]. (See "Rheumatic mitral stenosis: Overview of management", section on 'Indications for intervention'.)

While PMBC is not generally offered to asymptomatic patients with severe MS with resting PASP <50 mmHg and no new-onset AF, PMBC might be offered in the preconception setting on an individualized basis based on consideration of the following factors: evidence of hemodynamically significant MS on exercise testing (pulmonary artery wedge pressure >25 mmHg and/or mean mitral valve gradient >15 mmHg), barriers to provision of antenatal care (including urgent PMBC), severity of MS, and the suitability of the valve for PMBC [15,20,24].

Criteria for PMBC are discussed separately. (See "Percutaneous mitral balloon commissurotomy in adults".)

ANTEPARTUM CARE

Monitoring — Patients with MS should undergo cardiovascular assessment as early during pregnancy as possible, especially if there has been no opportunity for a preconception assessment.

The approach at the first antenatal visit is the same as for preconception assessment, with additional attention to the cessation of medications that may be teratogenic, such as angiotensin converting enzyme inhibitors or angiotensin II receptor blockers.

The care of patients with MS with high risk features, such as severe MS or pulmonary hypertension, should be discussed at a multidisciplinary conferences involving the pregnancy heart team, nursing, and social work to ensure that there is a written plan for follow-up during the antepartum period and also for labor and delivery.

The frequency of cardiac follow-up during pregnancy will be determined by the risk level. The 2018 European Society of Cardiology guidelines recommend monthly or bimonthly follow-up for moderate to severe MS (mitral valve area [MVA] ≤1.5 cm²), and at every trimester and prior to pregnancy for mild MS [15]. These are general guidelines, with some experts recommending biweekly follow-up visits until 30 weeks gestation followed by weekly visits until delivery [25]. B-type natriuretic peptide level can be helpful if clinical assessment is inconclusive in the symptomatic patient. As pregnant patients with MS will also be undergoing serial obstetric assessment, caregivers should consider establishing a combined cardiac-obstetric clinic where cardiac and obstetric assessment can be scheduled during the same clinic visit, reducing the need for travel for patients in whom functional deterioration is common as pregnancy advances. While there are no specific recommendations for echocardiographic assessments, at the minimum, an echocardiogram should be performed at the first antepartum visit and again during the third trimester visit. Transmitral gradient will increase as pregnancy progresses, but pressure half-time, planimetry, and continuity-equation are less preload-dependent methods to measure MVA. Pulmonary artery systolic pressure (PASP) may also increase.

At the time of each clinical assessment, history and signs of functional class deterioration, pulmonary congestion, and arrhythmias should be sought.

Medical management of heart failure

●Heart rate control – For pregnant patients with MS, we use a beta 1 selective blocker (table 5) (eg, the short-acting beta 1 selective blocker metoprolol starting with 12.5 to 25 mg orally twice daily) with dose titrated to a target heart rate of 70 to 90 beats per minute (bpm) while maintaining fetal heart rate ≥110 bpm, although heart rate goals for beta blocker therapy during pregnancy have not been established. We avoid atenolol use in this setting since its use is associated with low birthweight. (See "Management of heart failure during pregnancy", section on 'During pregnancy' and "Rheumatic mitral stenosis: Overview of management", section on 'Medical management of heart failure'.)

Digoxin can also be used for heart rate control in patients with AF but may be less effective in reducing heart rate than beta blockers. (See 'Management of arrhythmias' below.)

●Treatment of early signs of heart failure – Functional deterioration and/or an elevated PASP (>40 mmHg) may be warning signs of impending heart failure [15,19,23]. Mildly symptomatic patients with these signs are generally treated with restriction of physical activities, beta blocker therapy to reduce tachycardia and improve left ventricular filling, and a small dose of furosemide (eg, 20 to 40 mg orally) which is up-titrated as needed to induce diuresis. (See "Rheumatic mitral stenosis: Overview of management", section on 'Medical management of heart failure'.)

●Treatment of pulmonary edema – Patients with pulmonary edema should be admitted to a hospital and treated with oxygen, intravenous furosemide, and beta blocker therapy, as discussed separately. (See "Rheumatic mitral stenosis: Overview of management", section on 'Medical management of heart failure' and "Management of heart failure during pregnancy".)

The role of mitral valve intervention during pregnancy is discussed below. (See 'Intervention during pregnancy' below.)

Management of arrhythmias — Sustained or frequent palpitations should be promptly investigated. AF and other supraventricular tachycardias should be treated to prevent precipitation or worsening of heart failure and deleterious effect on uteroplacental perfusion. The key considerations in treating AF in pregnant patients with MS are prompt initiation of anticoagulation to reduce the risk of thromboembolism and rate control and rhythm control to reduce the risk of pulmonary edema [26].

Rate control with beta blockers or digoxin is generally the initial strategy for sustained AF. Beta blockers are more effective at heart rate control than digoxin as the renal clearance of digoxin is increased during pregnancy. As an elevated heart rate is crucial to maintain the augmented cardiac output in later pregnancy, the goal of ventricular rate control should be at 70 to 90 bpm rather than <60 bpm as in nonpregnant state. A target heart rate during pregnancy of <80 bpm has also been suggested [27].

As in nonpregnant settings, electrical cardioversion should be considered when the ventricular rate or symptoms are responding poorly to rate control or when there is hemodynamic instability. Transesophageal echocardiography should be performed prior to electrical cardioversion to exclude left atrial thrombus, which is a contraindication to electrical cardioversion. Left atrial thrombus may be present even if the duration of AF is less than 48 hours, since left atrial thrombus has been identified in some patients with MS in sinus rhythm [28]. (See "Prevention of embolization prior to and after restoration of sinus rhythm in atrial fibrillation", section on 'Transesophageal echocardiography-based approach'.)

Electrical cardioversion is considered to be generally safe for the fetus based on case reports and case series [15,26]. Once the fetal viability is reached, monitoring of the fetal heart rate during and following the cardioversion procedure and performance of the procedure in a facility that has the capability of performing immediate cesarean deliveries are advised [26]. The fetal safety profile is considered when choosing an antiarrhythmic agent for maintenance of sinus rhythm, as discussed separately. (See "Supraventricular arrhythmias during pregnancy", section on 'Rhythm control versus rate control'.)

Anticoagulation — Standard indications for anticoagulation in patients with rheumatic MS apply during pregnancy. Patients with MS and AF, atrial flutter, left atrial thrombus, or an embolic event require anticoagulation. (See "Rheumatic mitral stenosis: Overview of management", section on 'Prevention of thromboembolism'.)

In patients who require anticoagulation, low molecular weight heparin (or intravenous unfractionated heparin for hospitalized patients) is commonly used during pregnancy to avoid the potential teratogenicity and fetopathic effects of warfarin. Management of anticoagulant therapy during pregnancy, including regimens for discontinuation of heparin prior to delivery, is discussed further separately. (See "Anticoagulation during pregnancy and postpartum: Agent selection and dosing".)

Direct oral anticoagulants are not used in patients with rheumatic MS and are not used during pregnancy, as discussed separately. (See "Rheumatic mitral stenosis: Overview of management", section on 'Choice of anticoagulant' and "Anticoagulation during pregnancy and postpartum: Agent selection and dosing", section on 'Anticoagulants that are generally avoided during pregnancy'.)

Intervention during pregnancy

Limited indication — Intervention during pregnancy (preferably by percutaneous mitral balloon commissurotomy [PMBC]) is reserved for those patients with severe symptoms despite maximal medical therapy and hospitalization. With appropriate care including judicious use of beta blockers and/or diuretics, intervention during pregnancy can be avoided in most patients with MS.

Two observational studies including pregnant patients with MS as well as other heart lesions reported an association between antepartum cardiac complications and the frequency of premature labor [29,30]. This observation is pertinent to planning the timing of delivery for the patients with MS who have developed cardiac complications close to term.

Choice of intervention — When intervention is required antepartum due to severe heart failure symptoms despite maximal medical therapy and hospitalization, PMBC is the preferred intervention, if feasible (generally Wilkins score <8; possibly also with an intermediate Wilkins score of 9 to 12 in this setting) [19]. However, PMBC is contraindicated if mitral valve morphology is prohibitive, mitral regurgitation is moderate or greater, or if left atrial thrombus is present [19]. Criteria for PMBC are discussed separately. (See "Percutaneous mitral balloon commissurotomy in adults", section on 'Evaluation of candidates for PMBC'.)

Cardiac surgery during pregnancy is avoided if possible, since it is associated with high risk of fetal loss and implantation of a prosthetic valve is associated with complications (including issues related to complication) during pregnancy. (See "Management of risks of prosthetic valves during pregnancy" and "Management of antithrombotic therapy for a prosthetic heart valve during pregnancy".)

If PMBC is not available, closed mitral commissurotomy is an alternative, with the same contraindications as PMBC [14].

Open-heart mitral valve surgery is reserved for patients with refractory severe symptoms who are not candidates for (or fail to respond to) PMBC.

PMBC procedure — Consultation with maternal-fetal medicine and neonatology specialists is essential in planning the timing of PMBC in order to weigh the maternal and fetal risks of continuing medical therapy versus the maternal and neonatal risks if emergency delivery is required. Selection of a time for PMBC during pregnancy involves balancing competing risks, with involvement of the patient in the decision. If emergency delivery is required because of maternal compromise during the procedure, neonatal outcome generally improves with advancing gestational age. However, delaying the procedure until later in gestation increases the chances of maternal decompensation if MS is severe, and, in turn, increases the chances of emergency delivery which adversely affects maternal and fetal survival.

The procedure is best done at an experienced center after the period of organogenesis (>20 weeks) but prior to mid to late third trimester when the gravid uterus can interfere with catheter access and hemostasis with the femoral approach. Performing PMBC between 26 to 30 weeks of pregnancy has been proposed to be the preferred time to reduce the risk of extreme prematurity if there is a need for early delivery due to procedural complications [19]. However, PMBC may need to be performed earlier in pregnancy in those with refractory class IV symptoms or heart failure despite maximal medical therapy.

During PMBC, the radiation dose should be minimized by using abdominal shielding and keeping exposure times as short as possible. The fetal heart rate should be monitored continuously and assessed by an obstetric provider in case maneuvers for fetal resuscitation (eg, modification of maternal position, increased fluids, increased oxygenation) are indicated. Resources should be readily available for emergency cesarean delivery and care of a premature infant. Furthermore, the anesthetic management of the pregnant patient during PMBC involves additional considerations [31]. (See "Percutaneous mitral balloon commissurotomy in adults" and "Anesthesia for nonobstetric surgery during pregnancy".)

The effectiveness and safety of PMBC during pregnancy has been studied in over 700 patients. A study of 246 pregnant patients who underwent PMBC during pregnancy reported a procedural complication rate of 1.8 percent and two deaths from stroke [19]. Longitudinal studies have reported normal growth and development of children born to patients who underwent PMBC during pregnancy. Fetal radiation exposure can be minimized with the use of echocardiography. An important caveat is that patients reported in the above-mentioned studies represent a highly selected group and so PMBC should continue to be reserved for patients with hemodynamic deterioration despite optimal medical therapy.

PERIPARTUM CARE

Delivery

●Timing – Patients with MS with high-risk features (severe MS, pulmonary hypertension, history of cardiac complications prior to or during pregnancy) or who live a considerable distance from the delivering hospital are among those who may benefit from induction of labor to ensure that appropriate specialists are readily available during labor and delivery. Home births should be discouraged [14]. (See "Anesthesia for labor and delivery in high-risk heart disease: General considerations", section on 'Induction of labor'.)

●Mode of birth – With the use of regional anesthesia to attenuate the spikes in cardiac output during labor, almost all patients with MS can undergo vaginal delivery with an assisted second stage. (See "Anesthesia for labor and delivery in high-risk heart disease: General considerations", section on 'Vaginal "cardiac delivery"'.)

Cesarean delivery is generally reserved for obstetric/medical indications, including:

•Maternal warfarin anticoagulation with a therapeutic international normalized ratio (INR) is an indication for cesarean delivery because the fetus is also anticoagulated, which increases the risk of fetal intracranial hemorrhage. (See "Anticoagulation during pregnancy and postpartum: Agent selection and dosing", section on 'Birth'.)

•Refractory heart failure resulting in need for intubation and ventilation. This should occur rarely with state of the art antepartum cardiac care and careful monitoring [17].

•In addition, a cesarean delivery is considered on an individualized basis for patients with very severe MS (mitral valve area [MVA] <1 cm²) without heart failure and for patients with MS with heart failure not requiring intubation based upon factors including the patient's hemodynamic status, anticoagulant status, parity, cervical status, gestational age, past obstetric history, and the size of the fetus [27].

●Monitoring – Maternal pulse, oxygen saturation, and blood pressure are generally effectively monitored noninvasively but this practice reflects the provider's practice style. Invasive hemodynamic monitoring such as arterial lines, central venous line, and/or pulmonary artery catheters entail some risk and are rarely necessary [32]. Invasive hemodynamic monitoring is justified only if the hemodynamic status cannot be reliably assessed noninvasively. (See "Acquired heart disease and pregnancy", section on 'Management of labor and delivery'.)

Endocarditis prophylaxis — Endocarditis prophylaxis is not routinely recommended for uncomplicated vaginal or cesarean delivery. In patients with the highest risk lesions (eg, patients with prosthetic heart valves) with established infection that could cause bacteremia (such as chorioamnionitis or pyelonephritis) the underlying infection should be treated in the usual fashion; treatment should include an intravenous regimen effective for infective endocarditis prophylaxis. (See "Pregnancy and valve disease", section on 'Endocarditis prophylaxis' and "Clinical chorioamnionitis" and "Urinary tract infections and asymptomatic bacteriuria in pregnancy", section on 'Acute pyelonephritis'.)

Postpartum care

Early postpartum care

●Setting – Patients at high risk of cardiovascular complications (including those with severe MS [MVA ≤1.5 cm²]) should be monitored after delivery in a special care unit (eg, an intensive care, coronary care, or recovery room setting) where cardiac complications can be monitored and promptly treated. Patients admitted to a special care unit should be monitored for at least 24 hours, as postdelivery fluid shifts may be delayed in the presence of regional anesthesia. (See "Anesthesia for labor and delivery in high-risk heart disease: Specific lesions", section on 'Obstructive lesions'.)

Extended (at least 72 hours, not necessarily in a special care unit) postpartum monitoring for heart failure should be considered for patients with severe MS [27].

●Diuretic – We suggest routine administration of a single dose of intravenous loop diuretic (eg, furosemide 20 to 40 mg) during the first several hours after delivery to patients with severe MS (MVA ≤1.5 cm²) to reduce the likelihood of redistribution edema from autotransfusion following birth [25].

●Anticoagulation – For patients who require ongoing anticoagulation, anticoagulation can be resumed once there is no evidence of early or late postpartum hemorrhage.

Lactation — Most cardiac medications are excreted in breast milk but in such small amounts that their use is generally compatible with breastfeeding [33]. An exception is amiodarone, which affects the newborn thyroid, so breastfeeding is contraindicated during maternal use of amiodarone. Beta blocker selection and the compatibility of other heart failure medications with lactation is discussed separately. (See "Management of heart failure during pregnancy", section on 'Drugs'.)

Contraception — Contraception can be restarted based on guidelines extrapolated from those for patients without heart disease. Combination hormonal contraception is avoided in patients with valvular heart disease associated with high risk during pregnancy, including patients with MS. Reasonable alternatives (benefit outweighs risk) include intrauterine device, progestin-only implant, depot medroxyprogesterone acetate, and progestin-only pill [34]. (See "Contraception: Postpartum counseling and methods" and "Contraception: Counseling and selection".)

Outpatient follow-up — While there are no specific guidelines on the timing of postpartum assessments, cardiac assessment at four to six weeks postpartum will provide an opportunity to screen for postpartum deterioration, adjust cardiac medications, and discuss contraception choices.

As the cardiovascular changes of pregnancy do not fully resolve until the sixth postpartum month, a repeat clinical assessment with echocardiography after the sixth postpartum month will serve as the baseline for future follow-up, including risk stratification for future pregnancies. Elective cardiovascular invasive procedures should be delayed until after the sixth postpartum month to avoid unnecessary thromboembolic risk.

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Cardiac valve disease" and "Society guideline links: Management of cardiovascular diseases during pregnancy".)

SUMMARY AND RECOMMENDATIONS

●Risk associated with MS – In pregnancy in patients with mitral stenosis (MS), maternal and fetal risk increases with increasing severity of MS (table 1). Maternal complications include heart failure, atrial arrhythmias, and thromboembolic events. Perinatal complications including premature labor, low birth weight, premature delivery, and perinatal death. Maternal mortality has been described in patients with severe MS, with most reports in resource-limited settings.

●Role of pregnancy heart team – Individuals with MS should receive specialized evaluation, counseling, and management by a multidisciplinary pregnancy heart team prior to, during, and following pregnancy. (See 'Role of pregnancy heart team' above.)

●Preconception care – Prepregnancy counseling by a pregnancy heart team is an essential component of care for females of child-bearing potential who have MS. For those individuals who do not present until they are pregnant, counseling should be performed as early in pregnancy as possible. The purposes of preconception (or pregnancy) counseling are to provide risk assessment and discuss management to reduce risk and mitigate effects of potential complications (table 2).

●Evaluation – Routine preconception evaluation includes a careful cardiac history and physical examination, 12-lead ECG, and comprehensive transthoracic echocardiogram. Exercise testing is helpful for selected patients with severe MS with uncertain functional status and for selected patients with symptoms on exertion and resting hemodynamics consistent with progressive MS.

●Stages of MS – MS is staged based on integration of information generally obtained from echocardiography (valve anatomy, valve hemodynamics, secondary hemodynamic effects) and patient symptoms (table 3). (See 'Stages of MS' above.)

●Risk stratification – Stratification of maternal risk in a patient with MS can be performed using the CARPREG II risk score, the modified World Health Organization (WHO) classification system, or the DEVI score. Regardless of the risk prediction tool chosen, risk can be upgraded or downgraded based on the clinician's assessment of adherence, access, and other test results, such as exercise test results. (See 'Risk stratification' above.)

●Preconception intervention – Patients with rheumatic MS with a standard indication for mitral valve intervention (algorithm 1 and algorithm 2) should delay conception until after the intervention. Indications for mitral valve intervention are discussed separately. (See "Rheumatic mitral stenosis: Overview of management", section on 'Indications for intervention'.)

While percutaneous mitral balloon commissurotomy (PMBC) is not generally offered to asymptomatic patients with severe MS with resting pulmonary artery systolic pressure (PASP) <50 mmHg and no new-onset atrial fibrillation (AF), PMBC might be offered in the preconception setting on a case-by-case basis. Factors to consider include evidence of hemodynamically significant MS on exercise testing, barriers to provision of antenatal care (including urgent PMBC), and severity of MS. (See 'Preconception intervention' above.)

●Management of complications during pregnancy (See 'Antepartum care' above.)

•Arrhythmia management – Pregnant patients with MS and AF or atrial flutter are treated with anticoagulation and rate and rhythm control. For pregnant patients with MS, a beta 1 selective blocker (table 5) is used for rate control as in nonpregnant individuals. However, atenolol use is avoided during pregnancy due to its association with low birthweight. Choice of agent for rhythm control is discussed separately. (See "Supraventricular arrhythmias during pregnancy", section on 'Management'.)

•Treatment of heart failure – Heart failure is managed with beta blocker and diuretic therapy. Pregnant patients with MS are treated with beta 1 selective blocker (but not atenolol since its use is associated with low birthweight) (table 5) and diuretic therapy. The beta blocker dose is generally adjusted to maintain a maternal heart rate between 70 and 90 beats per minute (bpm) while maintaining a fetal heart rate ≥110 bpm.

Mitral valve intervention during pregnancy is rarely required and is reserved for patients with severe symptoms despite maximal medical therapy and admission to hospital. If required, PMBC is the procedure of choice, if feasible. (See 'Intervention during pregnancy' above.)

●Delivery – For pregnant patients with MS, vaginal delivery with assisted second stage is generally the preferred mode of delivery. Cesarean delivery is generally reserved for obstetric/medical indications including therapeutic range maternal international normalized ratio (INR) on warfarin (which is associated with risk of fetal intracranial hemorrhage) and refractory heart failure requiring intubation. In addition, a cesarean delivery is considered on an individualized basis for patients with very severe MS (mitral valve area [MVA] <1 cm²) without heart failure and for patients with severe MS with decompensated heart failure not requiring intubation based upon factors including the patient's hemodynamic status, anticoagulant status, parity, cervical status, gestational age, past obstetric history, and the size of the fetus. (See "Anesthesia for labor and delivery in high-risk heart disease: General considerations", section on 'Route of delivery' and "Anesthesia for labor and delivery in high-risk heart disease: Specific lesions", section on 'Obstructive lesions'.)

●Early postpartum care – Patients with severe MS should be monitored in a special care unit for at least 24 hours postpartum. We suggest a single dose of intravenous loop diuretic (eg, furosemide 20 to 40 mg) during the first several hours after delivery (Grade 2C) to reduce the risk of redistribution edema from autotransfusion. (See 'Peripartum care' above.)