Spontaneous coronary artery dissection

INTRODUCTION — Spontaneous coronary artery dissection (SCAD) is a nontraumatic, noniatrogenic separation of the coronary arterial wall and is an infrequent cause of acute myocardial infarction. It is more common in younger patients and in women. Modern usage of the term SCAD denotes nonatherosclerotic causes, which is the primary focus of this topic. Other aspects of coronary heart disease in women and among the general population are discussed separately.

●(See "Clinical features and diagnosis of coronary heart disease in women".)

●(See "Coronary artery disease and myocardial infarction in young people".)

●(See "Initial evaluation and management of suspected acute coronary syndrome (myocardial infarction, unstable angina) in the emergency department".)

EPIDEMIOLOGY

Incidence and prevalence — In a Danish study, annual SCAD incidence was 0.7 among patients referred for angiogram and 0.2 among patients with acute coronary syndrome (ACS) [1]. In the general population, SCAD is the cause of ACS in 0.1 to 4 percent of cases [1-4].

The following prevalence has been described from the National Inpatient Sample (NIS):

●In a 2018 report of NIS of over 13 million patients who presented with an ACS between 2005 and 2015, the incidence of SCAD was reported at 0.49 percent [5].

●In a 2009 to 2014 study of 750,000 patients with myocardial infarction who underwent coronary angiography, SCAD was reported in 0.98 percent [6].

However, these estimates likely under-reported the true incidence of SCAD, as this disease was underdiagnosed and misdiagnosed, especially during that time period.

Among women ≤50 years old with ACS, SCAD may account for nearly one-quarter of cases [7].

Sex — SCAD is more common in females than males.

●SCAD in females – Although classically thought to affect young women, SCAD is now increasingly recognized to also occur in older and postmenopausal women. In 327 patients, 57 percent of women affected were postmenopausal [8]. In the largest multicenter prospective SCAD registry to date (the Canadian SCAD Cohort Study), the mean age of the 750 SCAD patients was 51.8 years, with 9.2 percent older than age 65, and 88.5 percent were women [9]. In two other studies of 87 and 168 patients, the mean age was 43 and 52 years, and 82 and 92 percent were women, respectively [7,10].

●SCAD in males – Men account for <10 to 15 percent of SCAD cases. However, mechanistically, males are more likely to have coronary dissection that is related to atherosclerosis rather than nonatherosclerotic SCAD [11]. Men present at slightly younger ages (mean age 48.6 versus 52.3 years in women) [12].

PATHOPHYSIOLOGY — The underlying mechanism of nonatherosclerotic SCAD is not fully understood. Proposed mechanisms likely include the following:

●Intimal tear and bleeding of vasa vasorum – These processes result in intramedial hemorrhage [13]. This can result in the creation of a false lumen filled with intramural hematoma [14].

Pressure-driven expansion of the false lumen by an enlarging hematoma may lead to luminal encroachment and subsequent myocardial ischemia and infarction. Intramural hematoma involving the outer two-thirds of the media is common.

●Inflammation – Histological studies have shown an inflammatory reaction (eg, eosinophilic infiltrates) in the adventitia. This is suggestive of periarteritis that may breakdown the medial-adventitial layer predisposing the artery to dissection. However, this inflammatory response may be reactive rather than causative [15].

●Tortuosity – One retrospective study has proposed that coronary artery tortuosity may be a marker for or a potential mechanism for SCAD [16]. In this study, the coronary angiograms of 246 patients with SCAD were compared with 313 controls. Tortuosity, as defined by the presence of ≥3 consecutive curvatures of 90 to 180 degrees measured at end-diastole in a major epicardial coronary artery ≥2 mm in diameter, was found in 78 and 17 percent, respectively. However, the presence of coronary tortuosity was also associated with extracoronary vasculopathy (eg, fibromuscular dysplasia [FMD]) [17,18]; as such, it is more likely that the tortuosity (similar to dissection) is a manifestation of the underlying predisposing vasculopathy.

Whereas nonatherosclerotic SCAD can cause extensive dissection lengths (especially in the presence of arterial fragility from predisposing arteriopathies) [19,20], SCAD associated with atherosclerosis is typically limited in extent by medial atrophy and scarring [21].

ETIOLOGIES AND DISEASE ASSOCIATIONS — In over 50 percent of SCAD cases, there are identifiable cardiocirculatory stressors that may increase the risk of acute SCAD events; this is especially true if there is preexisting arteriopathy such as fibromuscular dysplasia (FMD) [8,10]. Recreational drug use and high-dose hormonal therapy have also been described as etiologies in these studies.

Idiopathic — In most cases, a predisposing arterial disease association or cause is identified [22]. However, up to 20 percent of cases are labeled as idiopathic [10].

Pregnancy and postpartum — Postpartum status was reported in 2 to 18 percent of cases [7,9,10]. In these patients, dissection may be a consequence of increased physiological hemodynamic stresses or from hormonal effects weakening the coronary arterial wall [15,23]. The exposure to recurrent and chronic hormonal pregnancy changes can further increase SCAD risks in women with multiple previous births (multiparity) [23].

Patients with pregnancy-associated SCAD have more severe presentations and may be at higher risk for recurrence. (See 'Pregnancy, preconception counseling, and contraception' below.)

Other hormonal causes — In addition to pregnancy, SCAD has been associated with other hormonal changes (some of these may also be considered a trigger of SCAD). (See 'Triggers' below.)

●In vitro fertilization [24]

●Hormonal therapy in transgender individuals [25]

●Oral contraception [26]

●Hormone replacement therapy (oral [27] and topical [28])

●Menstrual cycle [29,30]. It is unknown if the association with SCAD is causal.

Genetic cause — Recently identified associated genetic markers appear to increase the risk of SCAD; these require further investigation [31-33].

Other disease associations — Most patients presenting with SCAD do not have conventional risk factors for coronary heart disease [7,10].

●Migraines – In people with SCAD, migraines are common; studies have reported prevalence rates between 42 and 52 percent [34,35]. There may be a shared pathophysiology underlying SCAD and migraines; however, studies have not confirmed such pathways. One proposed shared mechanism is vascular dysfunction or link with FMD; in the latter, migraine is also frequently reported.

●Fibromuscular dysplasia – Among patients with SCAD, the coexistence of FMD is common. In a study of 168 patients with SCAD, FMD was found in about 80 percent [10]. In this study, which screened all patients with invasive or noninvasive angiography of the cerebral, iliac, or renal circulations, FMD was diagnosed in 72 percent in one or more territories. Other studies of patients with SCAD have found a similarly high prevalence of extracoronary vascular abnormalities, including FMD, dissection, tortuosity, and aneurysms [16]. In contrast, association with systemic inflammatory conditions appeared to account for a small proportion of cases [7,10]

●Connective tissue disorders – In a small proportion of cases (about 5 percent), SCAD can be associated with connective tissue diseases such as Marfan or vascular Ehlers-Danlos syndrome, where medial degeneration has been proposed to weaken the arterial wall and predispose to spontaneous dissections [8,36,37]. (See "Clinical manifestations and diagnosis of Ehlers-Danlos syndromes".)

●Autoimmune disorders – Although case reports have raised the possibility that autoimmune disease is involved in the etiology of SCAD, a 2020 nested case control study of 114 people with SCAD and 342 control participants found no association between autoimmune disease and SCAD [38].

●Atherosclerosis – Atherosclerosis can cause coronary dissection, and it is a distinct variant, but it is excluded from the contemporary definition of nonatherosclerotic SCAD. (See 'Pathophysiology' above.)

CLINICAL MANIFESTATIONS

Common scenarios — SCAD should be considered in any young patient who presents with an acute myocardial infarction or cardiac arrest, especially if they are female and have no risk factors or history of coronary heart disease.

The clinical presentations of acute myocardial infarction and cardiac arrest are discussed in detail separately:

●(See "Initial evaluation and management of suspected acute coronary syndrome (myocardial infarction, unstable angina) in the emergency department", section on 'Clinical presentation'.)

●(See "Initial evaluation and management of suspected acute coronary syndrome (myocardial infarction, unstable angina) in the emergency department", section on 'Physical examination'.)

●(See "Overview of sudden cardiac arrest and sudden cardiac death".)

Predisposing factors — Other potential predisposing factors that may be present in patients upon history taking include the following [7,8,10,39,40]:

●Fibromuscular dysplasia (FMD) (see "Clinical manifestations and diagnosis of fibromuscular dysplasia")

●Postpartum status, multiparity (≥4 births)

●Connective tissue disorders

●Systemic inflammatory conditions

●Hormonal therapy

Triggers — Several factors can trigger an episode of acute SCAD (table 1).

●Emotional stress – Emotional stress precede the event in approximately 50 percent of cases [9,10].

●Exercise – Intense exertion precede the event in 28.9 percent of cases, including isometric stress lifting/pushing >50 pounds in 9.8 percent of cases [9,10]. Males are more likely than females to have isometric exertion as a trigger of SCAD [12].

●Hormonal – Endogenous and exogenous sex hormones such as estrogen and progesterone may trigger SCAD. (See 'Other hormonal causes' above.)

Signs and symptoms — Patients with nonatherosclerotic SCAD usually present with signs and symptoms characteristic of acute coronary syndrome (ACS), including ischemic electrocardiographic (ECG) changes and elevated cardiac biomarkers, along with the following symptoms:

●Anginal chest pain (and/or arm, neck, or back discomfort)

●Diaphoresis

●Nausea and/or vomiting

●Dyspnea

In a study of patients presenting with SCAD, chest pain was the most common symptom presentation in 96 percent of cases; less common symptoms include arm, neck, or back pain; nausea or vomiting; diaphoresis; and dyspnea [1,7,41].

●ECG changes – Among patients with acute SCAD, ischemic ST changes on ECG are very common [42]. In a registry of 1079 patients with SCAD who presented to the emergency department, the initial ECG showed ST elevation in 46 percent, T wave abnormality in 22 percent, and normal ECG in 16 percent of patients. A smaller proportion of patients had ST depression (6 percent) and ST abnormality 9 percent. (See "Initial evaluation and management of suspected acute coronary syndrome (myocardial infarction, unstable angina) in the emergency department", section on 'Clinical presentation' and "Approach to the patient with suspected angina pectoris".)

DIAGNOSIS — Once SCAD is suspected, coronary angiography should be performed as early as possible, especially if the ECG shows ST-segment elevation. (See "Overview of the acute management of ST-elevation myocardial infarction".)

ECG — In any patient with suspected SCAD, a 12-lead ECG is one of the first diagnostic steps.

Echocardiography — We routinely perform a transthoracic echocardiogram to assess left ventricular global and regional systolic function. In subtle angiographic cases of SCAD, focal wall motion abnormalities can help delineate potential sites of dissection. The echocardiogram is also useful for differentiating from Takotsubo syndrome, assessing left ventricular global and regional function at the point of care, and assessing prognosis.

Coronary angiogram — In the absence of prior trauma, the diagnosis of SCAD is made in most patients at the time of coronary angiography. A contemporary angiographic series has shown that stereotypical changes of intimal disruption with multiple radiolucent lumen were seen in <30 percent of nonatherosclerotic SCAD cases [8,10]. The majority of SCAD cases had long and diffuse narrowing on angiography due to intramural hematoma, and this appearance was frequently unrecognized on angiography, leading to underdiagnosis of this condition.

The coronary angiographic appearance of SCAD has been classified into three types (image 1A-C) [43]:

●Type 1 – Pathognomonic contrast dye staining of arterial wall with multiple radiolucent lumen, with or without the presence of dye hang-up or slow contrast clearing [7].

●Type 2 – Diffuse long and smooth stenosis that can vary in severity from mild stenosis to complete occlusion

●Type 3 – Mimics atherosclerosis with focal or tubular stenosis and requires optical coherence tomography (OCT) or intravascular ultrasound (IVUS) to differentiate the cause.

At the time of coronary angiography, the following findings were noted:

●The left anterior descending coronary artery was the most frequently affected vessel (in 40 to 70 percent of cases) [7,9,10]. The left main coronary artery was involved in 13 percent in one series that included only ST-elevation myocardial infarction SCAD patients [4], with other series showing much lower incidence of left main coronary artery involvement (approximately 2 percent).

●The most commonly observed angiographic type was 2 (60 to 67 percent) [10]. (See 'Diagnosis' above.)

●Most patients had only one coronary artery involved (approximately 87 percent), but multivessel involvement of noncontiguous coronary segments was not infrequent [9,44].

In patients for whom the diagnosis is considered but not secured with coronary angiography, the following adjunctive tests may be helpful:

●Intracoronary imaging with OCT or IVUS – With these imaging modalities, the SCAD diagnosis can be made when intramural hematoma and/or a double lumen is seen. (See "Intravascular ultrasound, optical coherence tomography, and angioscopy of coronary circulation".)

OCT has higher spatial resolution and can therefore identify intramural hematoma, endothelial tears, and the entry site of dissections (figure 1) [45]. The downsides of OCT in the diagnosis of SCAD include the possibility of propagating the false lumen due to the injection of contrast material required for imaging acquisition. IVUS has a higher tissue penetration depth compared with OCT and can characterize fibrous lesions and lipid collections. IVUS scan may be repeated during the same procedure.

●Repeat coronary angiography – This may be pursued four to six weeks later if the diagnosis is uncertain; a finding of spontaneous angiographic healing of the dissected segment supports the diagnosis of SCAD.

Alternative imaging tests — These are not the tests of choice when SCAD is being strongly considered. However, in patients with troponin-negative chest pain, these may be a noninvasive imaging option to aid in diagnosis.

Coronary computed tomographic imaging — Some studies have suggested roles for cardiac computed tomography (CT) angiography [46,47] with suspected SCAD [48]. However, a substantial proportion of acute SCAD cases can be missed on CT angiography, and therefore this imaging modality should not be used as first-line imaging to diagnose SCAD.

Cardiac magnetic resonance imaging — Cardiac magnetic resonance imaging can be useful to differentiate SCAD from other conditions in the differential diagnosis of myocardial infarction; this includes causes of nonischemic myocardial injury, such as Takotsubo syndrome or myocarditis [49]. (See "Clinical utility of cardiovascular magnetic resonance imaging", section on 'Ischemic heart disease'.)

MANAGEMENT

Goals of therapy — The goals of therapy are to preserve myocardial perfusion and cardiac function.

Initial management — In most SCAD patients, conservative therapy is the preferred strategy after the diagnosis is secured [3,18,50]; however, this depends on whether the patient is clinically stable or unstable. Also, the optimal management is uncertain, in part due to the limited clinical experience.

A wide range of approaches, including conservative management, emergency revascularization with percutaneous coronary intervention (PCI) or coronary artery bypass grafting, fibrinolytic therapy (with or without subsequent PCI), mechanical hemodynamic support, and cardiac transplantation have been reported [10,11,51,52].

Stable patients — Revascularization in patients with SCAD is technically challenging and associated with higher failure rates or complications [7,10,50,53]. A conservative approach is recommended unless there is ongoing ischemia, hemodynamic instability, or left main dissection. Angiographic "healing" of SCAD lesions has commonly been observed after conservative management [3,10]. The conservative approach to treating a myocardial infarction is discussed separately. (See "Overview of the acute management of ST-elevation myocardial infarction" and "Overview of the acute management of ST-elevation myocardial infarction", section on 'Patients who do not undergo reperfusion'.)

Data regarding the most effective initial treatment for patients with SCAD are limited; there are no randomized studies of conservative versus invasive treatment of SCAD. Observational studies suggest that an initial conservative approach is associated with similar mortality and cardiovascular disease events compared with invasive treatment but is associated with a lower incidence of target vessel revascularization. A meta-analysis of 24 observational studies including 1720 patients with SCAD compared outcomes of a conservative versus invasive approach. In this study, 61 percent of patients had an initial conservative approach. After a mean follow-up of 28 months, a conservative approach had numerically but not statistically lower rates of all-cause mortality compared with an invasive approach (2.9 versus 4.8 percent; odds ratio 0.81; 95% CI 0.31-2.08). Rates of cardiovascular death, myocardial infarction, heart failure, and SCAD recurrence were also similar in the conservative versus invasive groups. Target vessel revascularization was lower with conservative versus invasive treatment (5.9 versus 13 percent; odds ratio 0.50; 95% CI 0.28-0.90).

Unstable patients — In patients presenting with acute myocardial infarction who have symptoms of ongoing ischemia, hemodynamic compromise, or left main dissection, revascularization with PCI or coronary artery bypass grafting is generally pursued [3,10]. Fibrinolysis is not recommended for the treatment of SCAD.

Among 53 patients presenting with an ST-elevation myocardial infarction from SCAD, investigators report a 91 percent success rate with emergent PCI; however, the definition of success differed from other series [4]. The largest SCAD series to date of 750 patients reported a PCI success/partial success rate of 69.9 percent among 106 SCAD patients who underwent PCI [9].

The in-hospital prognosis was generally good for those managed either conservatively or with coronary artery bypass grafting, while the short-term outcome appeared less favorable for those managed with PCI [7,10,50].

●Acute PCI success was observed in less than 50 to 70 percent of cases [9,10,50].

●Long-term success with PCI without complication was observed in 30 percent only [10].

●Two-year major adverse event rate was 10 to 17 percent, with an observed recurrent dissection rate of 13 percent [10].

●In 189 patients presenting with a first SCAD episode, procedural failure rate was 53 percent in those managed with PCI. In the subgroup of patients presenting with preserved vessel flow, PCI failure occurred in 50 percent of patients [50].

PCI should only be pursued when there is a strong clinical indication, and consideration should be given to utilizing adjunctive intracoronary imaging to optimize stent strut apposition. PCI with SCAD is often technically challenging in part due to fragility of the vessel wall. Advancing coronary guidewires within the true lumen can be challenging. Any instrumentation (wiring, angioplasty, or stenting) can propagate dissection and occlude side branches. In addition, dissections often affect small caliber distal vessels and are extensive, requiring long stents with high likelihood of subsequent in-stent restenosis. Furthermore, temporal resolution of intramural hematoma in previously stented segments may increase the risk of late stent malapposition and stent thrombosis. The use of bioabsorbable stents may have theoretical advantages [23]. The use of cutting balloon to fenestrate the false lumen to decrease burden of intramural hematoma compression of true lumen may also have utility [54].

Long-term management

Pharmacologic — Patients are generally treated with long-term aspirin, beta blocker, and short-term clopidogrel, with the addition of a statin in patients with dyslipidemia [10,55]. There are no studies of the comparative effectiveness of these treatments in patients with SCAD. Ongoing prospective studies on SCAD should further elucidate the medical management of this challenging and relatively unexplored condition (NCT02188069 and NCT02008786).

●Aspirin – There are no randomized trials of aspirin therapy; the majority of patients with SCAD are given aspirin, preferably for the long term.

●Clopidogrel – Dual antiplatelet therapy is often given for 1 to 12 months following a SCAD event, although there is no supportive evidence with this therapy. It is reasonable to discontinue clopidogrel after healing of the dissection is confirmed.

●Beta blocker – Among 327 patients, the use of beta blocker was associated with lower risk of recurrent SCAD (hazard ratio 0.36, p = 0.004) in multivariable analysis in the large 327-patient cohort [8]. The use of a beta blocker is sometimes limited by fatigue and hypotension.

●Statin – Statins are often given in patients with hyperlipidemia but not on a routine basis due to a theoretical concern that they can worsen the dissection [7].

●Antianginals – Patients with persistent chest pain post-SCAD may be treated with a long-acting nitrate or calcium channel blocker as needed.

The use of these medications among patients with acute coronary syndrome (ACS) or myocardial infarction is discussed separately. (See "Overview of the nonacute management of unstable angina and non-ST-elevation myocardial infarction", section on 'Pharmacologic therapy'.)

Nonpharmacologic

Avoidance of triggers — If a suspected trigger for SCAD is discovered, we counsel patients to avoid the trigger (see 'Triggers' above). Treatments for specific triggers such as anxiety, depression, and trauma have not been well studied.

Activities after spontaneous coronary artery dissection — We encourage patients to join a cardiac rehabilitation program after discharge. Although there are only a few differences in exercise recommendations for patients with SCAD compared with patients with myocardial infarction, a SCAD-specific rehabilitation program is recommended if available [56]. This program encompasses a multidisciplinary approach including exercise rehabilitation, psychosocial counselling, dietary and cardiovascular disease education, and peer group support.

Features of a cardiac rehabilitation program specific for patients with SCAD include the following:

●To reduce arterial shear stress, target exercise heart rate is recommended at 50 to 70 percent of heart rate reserve, and systolic blood pressure during exercise is limited to <130 mmHg.

●Exercise is adjusted to upper heart rate target to achieve rating of perceived exertion of "moderate" to "somewhat difficult."

●Women are instructed to avoid lifting weights >20 to 30 pounds, and men should avoid lifting >50 pounds.

Such a program was shown to be safe and beneficial in an uncontrolled cohort of 70 SCAD patients who experienced improvement in chest pain, exercise capacity, and psychosocial well-being [56]. Long term, we recommend avoidance of intense competitive exercise.

Assessing for concomitant fibromuscular dysplasia — Since a significant proportion of patients with SCAD have associated extracoronary fibromuscular dysplasia (FMD) (see 'Other disease associations' above), we obtain full-body cross-sectional imaging (preferably with computed tomographic [CT] angiography) to diagnose concomitant FMD [3,57,58]. We only perform imaging for FMD with magnetic resonance angiography if the patient refused CT angiography (due to lower resolution of magnetic resonance angiography).

The screening and management of FMD are discussed in detail separately. (See "Clinical manifestations and diagnosis of fibromuscular dysplasia" and "Treatment of fibromuscular dysplasia of the renal arteries".)

Extracoronary FMD can predict long-term major adverse coronary events [59]. This was shown in a prospective cohort study in which 750 patients with SCAD were followed for a median of three years for major adverse coronary events (MACE; this was defined as mortality, recurrent myocardial infarction, extension of previous SCAD or de novo recurrent SCAD, and iatrogenic dissection). MACE occurred in 14 percent, and those with FMD had a higher hazard of MACE (hazard ratio 1.51, p <0.04).

Recurrent chest pain — In patients with SCAD, recurrent chest pain is common. Forty percent of individuals experienced recurrence of their chest pain after initial hospitalization for SCAD, and 16.5 percent were diagnosed with recurrent SCAD [42]. When a patient diagnosed with SCAD presents with recurrent chest pain, we generally pursue the same diagnostic work-up as we would in a patient initially presenting with SCAD. (See 'Initial management' above.)

Repeat coronary angiography — Repeat angiography is performed if clinically indicated (for patients presenting with another ACS) and in some cases, if the initial angiogram was not definitive.

Other cardiovascular conditions — Meticulous control of hypertension is recommended. Chronic treatment of ischemic cardiomyopathy follows guidelines for non-SCAD indications.

SEQUELAE — In a prospective multicenter study of 750 patients with SCAD (Canadian SCAD Cohort Study), the in-hospital major adverse event rate was 8.8 percent; adverse events included mortality, recurrent myocardial infarction, cardiogenic shock, and unplanned revascularization [9].

Sequelae can be divided into those occurring proximate to the initial SCAD presentation and those occurring months to years afterwards.

Acute

●In-hospital myocardial infarction – In a cohort of 327 patients who were followed prospectively (median follow-up 3.1 years) and in whom an initial conservative approach was applied in 83 percent, the recurrent in-hospital myocardial infarction rate was 4.6 percent, with unplanned revascularization occurring in 4.3 percent [7,10].

●Ventricular arrhythmias – Life-threatening ventricular arrhythmias have been reported in 4 to 14 percent of patients with SCAD [7,9,10].

●Cardiogenic shock – This was reported in 2 to 19 percent of patients with SCAD; not surprisingly, patients with ST-elevation myocardial infarction had a higher prevalence of shock [4,10].

●Dissection in noncoronary vascular beds – SCAD patients may simultaneously present with dissections in other vascular beds, such as the carotid or vertebral arteries [44]. This highlights that a subset of patients may have a systemic predisposing arteriopathy compounded by an intense systemic precipitating milieu (be it hormonal, inflammatory, emotional, or physical), which may complicate their presenting symptoms.

●In-hospital mortality – In a population-based national administrative database from 2004 to 2015, 66,360 patients were reported to have SCAD, and the in-hospital mortality was 4.2 percent [5]. In a prospective multicenter study of 750 patients with SCAD (Canadian SCAD Cohort Study), in-hospital mortality was relatively low at 0.1 percent [9].

Long-term

●Recurrent myocardial infarction – In a prospective study of 750 patients with SCAD from 22 centers in North America (Canadian SCAD Cohort Study), over a 3.1-year follow-up, 16.8 percent had recurrent myocardial infarction. ST-elevation myocardial infarction was present in 25 to 50 percent of patients, with the remainder presenting with non-ST-elevation myocardial infarction [10]. Very rarely (<1 percent of cases), there was no troponin elevation [9].

●Recurrent SCAD – In a multicenter prospective study, 750 patients with SCAD (Canadian SCAD Cohort Study) were followed for 3.1 years; 10.4 percent had recurrent SCAD [9]. In a separate series of 87 patients after a median of 47 months, the recurrence of SCAD was 17 percent [7]. In these patients, coronary tortuosity may be associated with a higher risk of recurrent SCAD [16].

●Long-term mortality – In the Canadian SCAD cohort study described above, the mortality rate at the three-year median follow-up was 0.8 percent [10].

Further prospective and ongoing SCAD studies (Canadian SCAD Cohort Study [NCT02188069] and the "Virtual" Mayo Clinic SCAD Registry [NCT01429727]) will help elucidate the long-term cardiovascular outcome of this condition.

PREGNANCY, PRECONCEPTION COUNSELING, AND CONTRACEPTION — In patients who had prior SCAD who are considering pregnancy or who are already pregnant, the timing, features, and prognosis of pregnancy-associated SCAD are important to discuss. When discussing pregnancy with patients with a history of SCAD, we emphasize potential risks, and if they choose to become pregnant, patients will require high-risk pregnancy multidisciplinary care.

●Pregnancy-associated SCAD – This most often presents early postpartum and is associated with a more severe presentation compared with SCAD not associated with pregnancy.

In a single-center registry including 54 females with pregnancy-associated SCAD, four people presented during pregnancy (7.4 percent), 48 within 12 weeks following delivery (89 percent), one following a first trimester miscarriage (2 percent), and one following a stillbirth at 36 weeks (2 percent) [60]. These findings were similar to a study from Kaiser Permanente Northern California in which 18 of 22 females with pregnancy-associated SCAD presented postpartum (81 percent) [61]. In both studies, the majority of patients presenting with SCAD postpartum did so within the first month post-delivery (70 to 83 percent) [60,61].

Although no patients died from pregnancy-associated SCAD in either registry, both studies showed that people who had SCAD during pregnancy had more severe presentations compared with those who had SCAD that was not related to pregnancy [60,61]. Patients with pregnancy-associated SCAD had more proximal and multivessel coronary artery dissections, more heart failure, and lower average left ventricular ejection fraction on presentation compared with patients with SCAD not associated with a pregnancy. A separate study analyzed 13 patients who had died from pregnancy-associated SCAD from the MBRRACE-UK registry [62]. Among these deaths, three occurred during pregnancy, and 10 occurred postpartum (median 16 days postpartum [range 10 to 94]). Twelve patients had an out-of-hospital cardiac arrest; three underwent angiography, including one female who was alive at presentation to the hospital and two females who had angiography during active resuscitation. None underwent revascularization. Females who did not have angiography had autopsy-confirmed SCAD.

●Recurrence of SCAD with pregnancy – In people with SCAD (whether pregnancy related or not), there is a risk of recurrence during pregnancy or the postpartum period. Data from multiple SCAD registries were combined to evaluate 82 patients with pregnancy-associated SCAD [62], including the 13 from the previously mentioned United Kingdom registry who died. In the subset of 28 patients who had 37 pregnancies after their initial SCAD diagnosis, the following observations were reported:

•Conception after the most recent SCAD event occurred after a median of 30 months.

•Three women opted for medical termination (because of medical advice received about the risk of pregnancy), and seven spontaneous miscarriages occurred in three patients.

•Three pregnancy-associated major adverse cardiovascular and cerebrovascular events occurred. One was recurrent acute myocardial infarction at 19 weeks of gestation (this was thought to be recurrent SCAD and was managed without invasive angiography); the other two were angiographically confirmed recurrent SCAD events occurring within 12 months of delivery.

•No maternal or neonatal deaths were reported among those with prior SCAD who became pregnant.

●Contraception – We generally avoid estrogen-containing contraceptives, although the risk of adverse events in patients with SCAD has not been well studied.

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: Non-ST-elevation acute coronary syndromes (non-ST-elevation myocardial infarction)" and "Society guideline links: ST-elevation myocardial infarction (STEMI)".)

SUMMARY AND RECOMMENDATIONS

●Definition and epidemiology – Spontaneous coronary artery dissection (SCAD) is defined as a nontraumatic and noniatrogenic separation of the coronary arterial wall. (See 'Introduction' above.)

The incidence of SCAD is 0.5 to 0.7 among patients with acute coronary syndrome (ACS) and referred for angiography, respectively. It is likely more common in younger females presenting with ACS. (See 'Epidemiology' above.)

●Disease associations – Twenty percent of SCAD cases are idiopathic; other patients are pregnant or postpartum, have fibromuscular dysplasia (FMD), connective tissue disorders, and other associated conditions.

●Clinical manifestations – While uncommon, SCAD should be considered in any young patient, especially females, without a history of coronary heart disease or risk factors and who present with an acute myocardial infarction or cardiac arrest. (See 'Clinical manifestations' above.)

●Diagnosis – The diagnosis is usually made at the time of urgent coronary angiography. (See 'Diagnosis' above.)

●Management

•Initial management – We suggest conservative therapy as the preferred strategy for most patients, particularly those who are clinically stable (Grade 2C). (See 'Stable patients' above.)

In patients presenting with acute myocardial infarction who have symptoms of ongoing ischemia, hemodynamic compromise, or left main dissection, we suggest revascularization with percutaneous coronary intervention (PCI) or coronary artery bypass grafting (Grade 2C). (See 'Unstable patients' above.)

•Long-term management – We suggest that patients with SCAD be treated with antiplatelet and beta blocker therapy. Specific medications and duration of medication have not well studied; it is reasonable to discuss the duration of therapy with the patient in shared decision-making (Grade 2C). (See 'Long-term management' above.)

●Sequelae

•Acute sequelae – Acute sequelae include in-hospital myocardial infarction, ventricular arrythmia, cardiogenic shock, and in-hospital mortality. (See 'Acute' above.)

•Long-term sequelae – Long-term sequelae include recurrent myocardial infarction (17 percent) and recurrent SCAD (in 10 to 17 percent). Long-term mortality rates are relatively low in patients with SCAD (0.8 percent after three years). (See 'Long-term' above.)

●Pregnancy, preconception counseling, and contraception

•In patients with existing SCAD who are considering getting pregnant or who are pregnant, the timing, features, and prognosis of pregnancy-associated SCAD are important to discuss. (See 'Pregnancy, preconception counseling, and contraception' above.)

•Pregnancy-associated SCAD is most likely to occur in the first month postpartum. Although pregnancy-related SCAD has a more severe presentation than non-pregnancy-related SCAD, the occurrence of death is rare. Most pregnancy-associated SCAD deaths occur postpartum and as a result of an arrhythmia.

•Among females with a diagnosis of SCAD, there is a risk of recurrence during pregnancy or the postpartum period. If pregnancy is desired or takes place, referral to a team of providers (including a cardiologist) who manage high-risk pregnancies is recommended.

•We generally avoid estrogen-containing contraceptives, although the risk of adverse events in patients with SCAD has not been well studied.

ACKNOWLEDGMENT — The UpToDate editorial staff thank Pamela S. Douglas, MD, for her past contributions as an author to prior versions of this topic review.