Atrial fibrillation in patients undergoing noncardiac surgery

INTRODUCTION — Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical practice. Given the frequency of AF in the general population, many patients undergoing noncardiac surgery will have AF before, during, or after surgery. In some, the diagnosis is established, while in others it is new.

Patients with AF are at increased risk for death, heart failure, and thromboembolic events. This risk likely increases around the time of noncardiac surgery due to perioperative stresses.  

This topic will focus on management issues specific to these patients. Other relevant topics include:

●(See "Atrial fibrillation and flutter after cardiac surgery".)

●(See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation".)

●(See "Epidemiology, risk factors, and prevention of atrial fibrillation".)

●(See "Arrhythmias during anesthesia".)

EPIDEMIOLOGY — The prevalence of AF the United States is approximately 3 million [1], and it is increasing with time [2-4]. Projections of AF prevalence in the United States by the year 2050 range from 5.6 to 16 million [1,4]. (See "Epidemiology, risk factors, and prevention of atrial fibrillation".)

Thus, AF is common in patients who need to undergo noncardiac surgery. In a study of 38,047 patients undergoing noncardiac surgery over seven years, 4312 patients (11 percent) had a prior history of AF [5]. In the same study, a history of AF was associated with a 30-day postoperative mortality rate of 6.4 percent, compared with a rate of 2.9 percent in patients with coronary artery disease. This underscores the fact that perioperative mortality is twofold higher in patients with AF compared with those with coronary artery disease [5].

PATIENTS WITH KNOWN ATRIAL FIBRILLATION — In patients with known AF, elective noncardiac surgery should be deferred until rate and rhythm are felt to be optimal for surgery and a decision has been made as to how to manage anticoagulant therapy. (See 'Emergency surgery' below.)

Major cardiac events (eg, death, heart failure, or stroke) due to AF have two primary etiologies: AF with rapid ventricular response (leading to severe palpitations, cardiac ischemia, or global hemodynamic compromise) and systemic thromboembolism. The principal goals of the preoperative evaluation and management of patients with known AF are to ensure hemodynamic stability and optimal anticoagulation status in the perioperative period.

Management of rhythm or rate — Patients with known AF are typically managed long term with either a rhythm- or a rate-control strategy [6,7] (see "Management of atrial fibrillation: Rhythm control versus rate control").

A preoperative physical examination and electrocardiogram will clarify whether the patient is at their rate or rhythm control goal.

Rhythm control — Paroxysmal AF patients may present for noncardiac surgery in sinus rhythm or in AF (see "Paroxysmal atrial fibrillation", section on 'Management'). This is true for patients with or without ongoing drug therapy or prior catheter ablation.

Asymptomatic recurrences of AF are common in patients who are on antiarrhythmic drug therapy or who have had prior ablation. In the absence of symptoms or rapid rates, there is generally no need to restore sinus rhythm or delay surgery. Rhythm-controlling drugs should be continued throughout the perioperative period. For patients who are expected to be in sinus rhythm due to the infrequent nature of their AF paroxysms or due to successful rhythm control strategies such as the use of antiarrhythmic drug therapy or prior catheter ablation, the presence of AF may be unexpected. The failure of the rhythm control strategy should be investigated, unless surgery is urgent. A decision to proceed with surgery prior to addressing the failure of the rhythm control strategy will need to take into account the urgency of the surgery.

In some patients, it may be prudent to proceed with surgery, as restoration of sinus rhythm with manipulation of antiarrhythmic drug therapy or another ablation procedure may delay surgery for weeks to months. (See "Antiarrhythmic drugs to maintain sinus rhythm in patients with atrial fibrillation: Recommendations" and "Atrial fibrillation: Cardioversion" and "Atrial fibrillation: Catheter ablation".)

Rate control — Patients presenting in AF should have the rate adequately controlled to avoid rapid ventricular rates and the possibility of ensuing cardiac ischemia. We do not suggest cardioversion in the preoperative period because this would mandate uninterrupted systemic anticoagulation for a minimum of four weeks after restoration of sinus rhythm, which may increase the risk of bleeding during the surgical procedure or be contraindicated.

Major adverse cardiac events in AF patients undergoing noncardiac surgery may be due to inadequate rate control and attendant cardiac ischemia during the perioperative period. Rate control is most often achieved pharmacologically, with beta blockers, non-dihydropyridine calcium channel blockers, or (less frequently) digoxin.

Prior to surgery, heart rates between 50 and 100 beats per minute (bpm) are reasonable as long as the patient is asymptomatic [8]. Postoperatively, in our experience, heart rates as high as 120 bpm are reasonable given the stressors of pain or hypovolemia, as long as these increased heart rates do not cause hemodynamic instability or myocardial ischemia. (See "Control of ventricular rate in patients with atrial fibrillation who do not have heart failure: Pharmacologic therapy".)

Management of anticoagulation — Many AF patients receive long-term oral anticoagulation to reduce the risk of embolic events (see "Atrial fibrillation in adults: Use of oral anticoagulants"). While some surgical procedures can be performed safely on patients who are systemically anticoagulated [9,10], interruption of anticoagulation during the perioperative period is required in others where the perioperative bleeding risk is high. This issue is discussed in detail elsewhere. (See "Perioperative management of patients receiving anticoagulants".)

Certain surgical procedures (eg, cardiac device implantation) carry low bleeding risk, and may be performed safely without interruption of systemic anticoagulation [9]. In patients with high risk of periprocedural bleeding, however, interruption of anticoagulation may be necessary. Risk factors for periprocedural hemorrhage include recent major bleeding, thrombocytopenia, dual antiplatelet therapy, supratherapeutic anticoagulation (as indicated by international normalized ratio), or a history of perioperative bleeding in the past.

For those patients who will have their anticoagulation interrupted, thromboembolic risk and estimation of bleeding risk should be weighed to determine duration of anticoagulation cessation. Longer interruption will increase risk of systemic thromboembolism. Decisions about the timing and duration of anticoagulation interruption require communication between the surgical and anesthesia teams and the physicians managing the patient's anticoagulation. Suggestions for the discontinuation of non-vitamin K oral anticoagulants in the perioperative time period are made in a table (table 1). This will facilitate an accurate assessment of bleeding and stroke risks, and establish a plan for the conduct of anesthesia. For instance, neuraxial procedures are typically contraindicated if there has been anticoagulation with dabigatran within the prior four to five days or factor Xa inhibitors within the prior three to five days, and anticoagulation should not be restarted until 24 hours after catheter removal [11,12]. In addition, it is critical that the patient is involved in the risk conversation. Some patients may opt to defer elective surgery, knowing that there is always some risk of stroke associated with interruption of oral anticoagulation.

Determining when anticoagulation should be interrupted is critical, as premature interruption may unnecessarily increase stroke risk, and delayed interruption may increase surgical bleeding risk (see "Perioperative management of patients receiving anticoagulants", section on 'Timing of anticoagulant interruption'). In general, we suggest cessation of vitamin K antagonists roughly three to five days prior to anticipated surgery, and cessation of direct oral anticoagulants three days prior to surgery. Bridging therapy in patients at high risk for thromboembolism and taking warfarin may be performed with low molecular weight heparin, with the last injection typically delivered no less than 12 hours prior to surgery. Direct-acting oral anticoagulants (DOAC; also referred to as non-vitamin K oral anticoagulants [NOAC]) should be discontinued for one to three days prior to surgery, depending on the risk of surgery, renal function, and the specific DOAC [13-15]. Manufacturer guidelines can be useful for guidance.

The following are suggestions regarding anticoagulation cessation:

●Patients at highest risk of left atrial thrombus formation or embolization should undergo the shortest duration of anticoagulation cessation possible. Bridging therapy with low molecular weight heparin may be indicated if they are taking warfarin. Examples of such patients include those with CHA₂DS₂-VASc Score of ≥7, recent thromboembolic stroke or systemic embolism, recent cardioversion, or echocardiogram showing left atrial thrombus. If there has been an intracranial hemorrhage or major bleed in the prior three months, however, bridging may have more risk than benefit.  

●In those with a moderate risk of thromboembolism (CHA₂DS₂-VASc Score of 5 to 6 or prior thromboembolism >3 months prior), the bleeding risks of bridging will need to be balanced with risk of thromboembolism. Careful clinical decision making and discussion with the patient are encouraged. In general, if there is a high bleeding risk, bridging therapy should not be initiated. If the patient's bleeding risk is low and the patient has a history of a prior thromboembolic event, then bridging is encouraged. If there is a low bleeding risk and no prior thromboembolism, then bridging is not indicated. (See "Perioperative management of patients receiving anticoagulants", section on 'Bridging anticoagulation'.)

●Patients at low risk of thromboembolic events (CHA₂DS₂-VASc Score of ≤4) may safely interrupt anticoagulation for longer periods than those at high thromboembolic risk.

PATIENTS WITH NEWLY DISCOVERED ATRIAL FIBRILLATION — A new diagnosis of AF may be made at the time of preoperative evaluation. A few other patients will develop AF intraoperatively or in the first day or two after surgery (see 'Postoperative atrial fibrillation' below). Our approach to these patients is generally similar to that in patients with new onset AF not related to noncardiac surgery. (See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation".)  

Preoperative atrial fibrillation — AF diagnosed preoperatively may arise in the setting of a risk factor such as hypertension or from an underlying systemic disorder such as severe hyperthyroidism. Both the AF and the underlying disorder may be a source of perioperative risk unless recognized and managed. For these reasons, we suggest that newly discovered AF be treated as a potentially unstable condition that should preclude elective noncardiac surgery. Diagnosis and management of newly discovered AF are discussed elsewhere. (See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation".)

However, for these patients presenting for minor surgical procedures, typically of limited duration and complexity (eg, monitored anesthesia care using local anesthetics with minimal anticipated blood loss), it may be reasonable to safely proceed despite new onset AF, as long as the patient is asymptomatic and hemodynamically stable. These patients should subsequently be referred for early evaluation and management of AF. (See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation".)  

Data on rates of incident AF discovered immediately prior to noncardiac surgery are largely lacking. Given the prevalence of AF in the general United States population of roughly 5 million, and the observation that prevalence of both AF and indications for noncardiac surgery both increase with age and systemic illnesses including hypertension and diabetes mellitus, it is anticipated that health care providers will be confronted with newly discovered AF in the preoperative setting. (See 'Epidemiology' above.)

Intraoperative atrial fibrillation — For patients who develop intraoperative AF, the immediate concern is hemodynamic stability. Anticoagulation is not urgently required and can be considered after surgery. (See 'Anticoagulation after surgery' below.)

If there is hemodynamic instability such as hypotension, evidence of pulmonary congestion, or electrocardiographic evidence of myocardial ischemia, cardioversion should be performed intraoperatively, as soon as this can be attempted without compromising the surgical procedure. Since intraoperative cardioversion requires placement of external defibrillation pads, deep sedation or general anesthesia, and possible patient repositioning to a supine position, the decision to perform this procedure requires thoughtful discussion between the anesthesiologist and surgeon. If the patient is hemodynamically stable, it is reasonable to perform a cardioversion at the end of the surgery while the patient is already under anesthesia. However, the physiological stress that may have triggered AF may still be present and the patient may develop recurrent AF after cardioversion.

For those in whom cardioversion will not take place, rate control needs to be considered. Beta blockers or non-dihydropyridine calcium channel blockers are given to slow the heart rate intraoperatively in patients who develop AF. For most patients in the operating room, the heart rate goal is <100 to 110 beats per minute. The rate should also be guided by restoration of acceptable blood pressure and resolution of new electrocardiographic ST or T wave abnormalities.  

Intravenous esmolol 10 to 50 mg repeated as necessary or intravenous metoprolol 5 mg every five minutes for three doses is commonly used. Beta blockers should be used with caution in patients with known heart failure or volume overload. Another option is diltiazem 0.15 to 0.25 mg/kg given over two minutes as an intravenous bolus followed by infusion, which can then be titrated for effect. Diltiazem may be used in patients with heart failure if dosing is titrated cautiously [16].

These patients should subsequently be referred for early evaluation and management of AF. (See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation".)  

It is reasonable to continue the beta blocker or calcium channel blocker for four to six weeks after surgery [17].  

Postoperative atrial fibrillation — New onset AF is common after noncardiac surgery, with reported incidence rates between 0.4 and 3 percent [18-21]. Thoracic, pulmonary, vascular, and abdominal surgeries are associated with the highest risk of postoperative AF [21]. The underlying cause or trigger for AF may be systemic inflammation, increased adrenergic tone, electrolyte abnormalities, anemia, hypothermia, hypoxia, or hypervolemia [22-24]. Postoperative AF is associated with increased mortality, length of stay, and cost.

Patients are frequently not on telemetry when AF is first suspected, so it is not always clear when an episode began [22].

Predictors of AF include [18,20,23-26]:

●Male sex

●Prior history of AF

●Increased preoperative B-type natriuretic peptide

●Elevated heart rate

●Increased age

●Chronic kidney disease

●Hypertension

●Sepsis

●Heart failure    

●Valvular heart disease    

An electrocardiogram should be obtained to confirm the diagnosis, and electrolytes should be evaluated. Unless there is a clinical suspicion for an acute coronary syndrome or electrocardiographic evidence of cardiac ischemia or injury, cardiac biomarkers including troponin are usually not needed. However, if there is uncertainty about the presence of ischemia or if the patient cannot provide an adequate history postoperatively, it is not unreasonable to test biomarkers.

Reversible factors should be identified and addressed:

●Electrolyte abnormalities

●Hypoxia

●Acidosis

●Infection

●Pain

●Volume overload

Management of the AF is then dependent on symptoms, duration of AF, and need for rate or rhythm control. If a home medication such as a beta blocker has been stopped, it should be reinitiated if possible [27].

For those in whom sinus rhythm is desired, a rhythm control strategy should be pursued. (See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation".)

This approach is recommended for those with symptomatic AF despite good rate control or in those where rate control is difficult to achieve. Rhythm control may also be preferred in patients who are felt to be unlikely to have a recurrence of AF, such as those who are younger, with fewer comorbidities, and with a small left atrium. It can be considered also for those who have not spontaneously converted within 24 hours where the desire is to avoid anticoagulation if possible, especially in those with a high bleeding risk. However, >50 percent of patients with new onset postoperative AF will convert back to normal sinus rhythm within 24 hours on their own [18,22].

Either electrical or pharmacologic cardioversion can be attempted, with the choice based on the patient's status and the local practice pattern. Direct current transthoracic cardioversion is effective about 95 percent of the time in converting to normal sinus rhythm. As a starting point, 120 to 200 joules for biphasic defibrillators and 200 joules for monophasic defibrillators may be used [28]. If AF has been present for greater than 48 hours, transesophageal echocardiography to ensure absence of left atrial appendage thrombus is advisable. Anticoagulation strategy is discussed in detail elsewhere. (See "Atrial fibrillation: Cardioversion".)

For those who have contraindications to anesthesia or in whom external electrical cardioversion has failed, intravenous amiodarone or ibutilide may be considered. In one nonrandomized observational study, amiodarone and diltiazem were equivalent for thoracic surgery patients in terms of conversion to normal sinus rhythm [29]. Another study of critically ill patients in a cardiology intensive care unit showed that diltiazem provided better rate control than amiodarone with equivalent rate of conversion to normal sinus rhythm, but that diltiazem treatment had to be discontinued more frequently, owing to hypotension [30]. The dose of diltiazem used, however, was not titrated and was fixed at a high dose of 20 mg/hour.

Anticoagulation after surgery — In patients with AF who have undergone noncardiac surgery, we recommend an anticoagulation approach similar to that used after cardiac surgery (see "Atrial fibrillation and flutter after cardiac surgery", section on 'Our approach to postoperative anticoagulation'):

●If the patient is chronically on anticoagulation, it should be restarted when safe from a surgical bleeding perspective.

●For a single episode of AF lasting <48 hours, we do not recommend anticoagulation, unless there are very high-risk features (for thromboembolism) such as mitral stenosis.

●For those with multiple episodes of AF or a single episode lasting >48 hours, we recommend using the CHA₂DS₂-VASc Score to determine stroke risk (table 2), even though it has not been validated in the postoperative population. In those with scores ≥2, we recommend anticoagulation for four weeks, assuming the perioperative bleeding risks are considered acceptable. As there are no comparative data regarding the use of warfarin, direct thrombin inhibitors, and anti-factor Xa inhibitors in the postoperative population, the decision of which agent to be used should be based on bleeding risk, cost, and patient preference. (See "Atrial fibrillation in adults: Use of oral anticoagulants", section on 'Approach to anticoagulation'.)

●Owing to concerns of perioperative bleeding, we typically do not use bridging with intravenous heparin if a rate control strategy is used, unless there is a mechanical valve, CHA₂DS₂-VASc Score of ≥7, or systemic thromboembolic event within the prior three months.  

●Reassessment after four weeks is then made based on thromboembolic risk, bleeding risk, including the HAS-BLED score (table 3), and patient preference. For those who are felt to be high risk for stroke, even if recurrent AF has not been documented, it may be preferable to continue anticoagulation indefinitely. Ambulatory monitoring can also be used to guide decision making.

●For those who have documented recurrences of AF after four weeks, long-term anticoagulation should be continued based on the CHA₂DS₂-VASc Score. (See "Atrial fibrillation in adults: Use of oral anticoagulants", section on 'Summary and recommendations'.)

The risk of thromboembolism associated with new onset AF following noncardiac surgery has been evaluated in a few observational studies [21,31,32]. While the evidence is not strong, we interpret these studies as showing an increased risk of thromboembolism that is reduced with anticoagulation. The best available evidence comes from a 2018 registry study of over 1.5 million patients who underwent noncardiac surgery from 1996 to 2015, of whom 6048 were identified with postoperative AF. From these, 3830 patients were matched with 15,320 patients with nonvalvular AF. The long-term risk of thromboembolism was similar in the two groups (31.7 versus 29.9 events per 1000 person years; hazard ratio 0.95, 95% CI 0.85-1.07) during a mean follow-up of 3.2 years [21]. In addition, the risk of thromboembolism was comparably reduced (about 50 percent) with anticoagulation therapy in both groups.

EMERGENCY SURGERY — If a patient presents for emergent or urgent surgery and is found to have a new diagnosis of AF prior to surgery, the following questions need to be asked and answered:

●Does the patient need to have restoration of sinus rhythm prior to surgery?

In most cases, we do not attempt restoration of sinus rhythm, with either electrical or chemical cardioversion, prior to emergency surgery. The most common indication for doing so would be hemodynamic instability.

●Does the rate need to be slowed prior to surgery?

We believe that most patients will benefit from a ventricular rate in AF that is less than 140 beats per minute (bpm). In many patients, we attempt to slow the rate to 100 to 110 bpm unless this leads to hypotension.

Rate control can typically be achieved effectively and rapidly with an intravenous infusion of negative chronotropic drugs including esmolol, metoprolol, or diltiazem. These agents may significantly reduce blood pressure, which in some emergent situations may be detrimental and require vasoactive agents to provide systemic circulatory support.

●Does anticoagulant therapy need to be started prior to surgery?

In most cases, the initiation of anticoagulation can be deferred until after surgery. We do not recommend urgent transesophageal echocardiography prior to surgery to screen for left atrial appendage thrombus. Rather, decisions to proceed to surgery should be made on the basis of clinical risk assessment.

PATIENTS WITH ATRIAL FLUTTER — We manage pre-, intra-, and postoperative atrial flutter in the same manner as AF, as there is little published evidence regarding perioperative atrial flutter. Decisions regarding anticoagulation, rate control, and rhythm can be approached similarly. Direct current cardioversion of atrial flutter typically requires lower energy, and in most patients it can be accomplished with 50 to 100 joules for biphasic devices and 100 joules for monophasic devices.

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: Arrhythmias in adults".)

SUMMARY AND RECOMMENDATIONS

●Atrial fibrillation (AF) is highly prevalent in the population, and many individuals undergoing noncardiac surgery will carry the diagnosis or develop it in the perioperative period. (See 'Epidemiology' above.)

●The principal goals of the preoperative management of patients with known or newly discovered AF are to ensure hemodynamic stability and optimal anticoagulant status in the perioperative period.

●For patients with known AF:

•Prior to surgery, heart rates in AF between 50 and 100 beats per minute (bpm) are reasonable as long as the patient is asymptomatic. (See 'Management of rhythm or rate' above.)

•While some surgical procedures can be performed safely on patients who are systemically anticoagulated, interruption of anticoagulation during the perioperative period is required in others such as those in whom the perioperative bleeding risk is high. The decision to interrupt anticoagulation should be made on a case-by-case basis. (See 'Management of anticoagulation' above.)

●For patients with newly discovered AF:

•For individuals presenting for minor surgical procedures, typically of limited duration and complexity (eg, monitored anesthesia care using local anesthetics with minimal anticipated blood loss), it may be reasonable to proceed, as long as the patient is hemodynamically stable. (See 'Preoperative atrial fibrillation' above.)

•For patients who develop intraoperative AF, the immediate concern is hemodynamic stability. Anticoagulation is not urgently required and can be considered after surgery. For most patients in the operating room, the heart rate goal is <100 to 110 bpm. (See 'Intraoperative atrial fibrillation' above.)

•For those patients who develop postoperative AF (see 'Postoperative atrial fibrillation' above) and in whom sinus rhythm is desired, a rhythm control strategy should be pursued. This approach is recommended for those with symptomatic AF despite good rate control or in those where rate control is difficult to achieve. Rhythm control may also be preferred in patients who are felt to be unlikely to have a recurrence of AF, such as those who are younger, with fewer comorbidities, and with small left atrium.

•For many patients with a single episode of AF lasting <48 hours, we do not recommend anticoagulation, unless there are very high-risk features for thromboembolism, such as mitral stenosis. (See 'Anticoagulation after surgery' above.)