Spontaneous coronary artery dissection (SCAD) is a rare clinical event with little available information on etiology, treatment, or outcomes. Two cases of SCAD are presented and identified cases from the literature with complete data (n = 222) are reviewed and analyzed. Female patients (71.9%) were younger (40.4 versus 46.7; p < 0.001), less likely to have coronary artery disease (3.7 versus 20.6%; p = 0.01), more likely to have left anterior descending artery (46.4 versus 25.4%; p = 0.004) and left main artery involvement (14.9 versus 3.2%; p = 0.01), and less likely to survive (50.9 versus 22.2%; p < 0.001) compared to their male counterparts. Thirty percent were in the peripartum state. Multivariate predictors of death included female sex (OR 4.27; 95% CI 1.50 to 12.2), non-treatment (OR 35.5; 95% CI 10.7 to 118.1), and earlier decade of diagnosis (OR 0.28 per increase in decade after 1980; 95% CI 0.16 to 0.49). Survival was no different by treatment type and did improve over time.

       Spontaneous coronary artery dissection (SCAD) is a rare but potentially lethal event.^1,2 It is a separation between the intimal and medial wall of the coronary vessel. The potential result of the dissection is obstruction of the vessel lumen and subsequent myocardial ischemia. Prior to the widespread use of coronary angiography, diagnosis was made at autopsy.² From reported cases, some trends have been identified. There are reported associations with female sex,^2,3 exercise,^4–7 pregnancy and postpartum state,^8–12 coronary artery disease,^{2, 13, 14} and connective tissue disorders.^9,15,16 The left anterior descending artery is more affected in women; the right coronary artery is more often affected in men.² Most cases have no identifiable risk factor.^17,18 There is little information on etiology, management and outcomes for SCAD. We report two patients with SCAD that highlight the uncertainties surrounding the treatment and diagnosis of this disease. Consequently, we undertook a comprehensive literature review to identify risk factors, treatment strategies and outcomes for this disorder.

       Methods. We reviewed the literature to gather all reported cases of SCAD. We searched Medline from 1966 through January 2000 for “spontaneous coronary dissection” and “coronary dissection.” Additionally, we reviewed the bibliography of each retrieved article to ensure that all referenced cases were obtained (n = 284). A total of 222 cases were found in the published literature with information concerning history, treatment and outcome. Cases in which complete data were not available were excluded (n = 60). Cases were classified as surviving (alive) if patients survived the initial event and were discharged; patients who were diagnosed at autopsy or died during hospitalization were classified together as dead. Univariate statistical analysis (chi-square or unpaired corrected t-test) was used to classify sex differences in those patients with SCAD. Logistic regression analysis was used to identify risk factors for mortality from SCAD.

       Case Report 1. A 43-year-old female presented complaining of 24 hours of continuous burning chest pain, radiating into the left arm, associated with dyspnea and diaphoresis. She had no prior medical problems. Cardiac risk factors included tobacco use, family history of premature coronary disease, and hypertension treated with combination losartan/hydrochlorothiazide. Past surgical history included total hysterectomy and salpingoopherectomy for bleeding at age 22 without subsequent estrogen replacement.

Figure 1

This angiogram demonstrates a spontaneous dissection of the right coronary artery. The radiolucent line represents the intimal flap (black arrow).

       An electrocardiogram revealed sinus rhythm and 3 mm ST-segment elevation in the inferior leads, consistent with an evolving acute inferior wall myocardial infarction. The patient was treated with tissue plasminogen activator, as well as standard therapy for myocardial infarction. Within one hour of receiving thrombolytics, her chest pain resolved and the ST-segment elevations returned to normal. She was admitted to the coronary care unit.
       A diagnostic cardiac catheterization was performed to define the coronary anatomy. The left coronary system revealed only luminal irregularities, while the right coronary artery views displayed a significant dissection in the mid-portion, from the acute marginal branch extending into the posterolateral branch (Figure 1). The ejection fraction was calculated at 52%. Continued medical therapy of coronary artery disease was recommended, which included aspirin, heparin, and beta-blockade.
The patient remained stable on medical therapy with no recurrence of chest pain until the day following the procedure. She developed sudden onset of chest pain and quickly developed bradycardia and asystole. Attempts at resuscitation were unsuccessful. Autopsy revealed myocardial rupture as the cause of death.

       Case Report 2. A 47-year-old female presented to the emergency department with sudden onset of chest pain. Past medical history included hypertension treated with acebutolol, hypercholesterolemia treated with fluvastatin, and hypothyroidism treated with levothyroxine. Total creatine phosphokinase was 808, with elevated MB fraction. An electrocardiogram revealed sinus rhythm, with ST-elevation in the antero-lateral leads, depression in the inferior and lateral leads, and a nonspecific intraventricular conduction delay. She was treated with thrombolytics in the emergency department with resolution of chest pain and EKG changes. The patient was treated with standard medical therapy for coronary disease and had no complications. Catheterization on hospital day-four revealed spontaneous dissection of the first obtuse marginal. She had no other significant disease. Medical therapy was continued, and the patient was discharged in stable condition.

Figure 2

Mortality in 224 Patients with Spontaneous Coronary Artery Dissection (SCAD) by decade of occurrence.

       Five years later the patient developed another episode of severe midsternal chest pain. An electrocardiogram revealed that she had ST-elevation in the anterior leads with intermittent left bundle branch block. Urgent coronary angiography revealed a dissection of the proximal left anterior descending artery. An attempt was made at percutaneous intervention, however, the lesion could not be crossed. An intra-aortic balloon pump was placed, and minimally invasive coronary bypass was performed emergently. The left internal mammary artery was used to bypass the distal left anterior descending artery. The patient tolerated the procedure well and had an uneventful recovery. She continues to do well after two years of follow-up.

       Results. Of 224 cases of SCAD with complete data, 161 (71.9%) were women and 63 (28.1%) were men (Table 1). The number of reported cases of SCAD increased over time. Mortality was 42.9% (n = 96) and improved over time (Figure 2). The majority of reported cases had no risk factor for SCAD identified (61.2%, n = 137). Of the risk factors identified, the most frequent were pregnancy or postpartum state, coronary artery disease, and exercise. Less common risk factors included Marfan’s syndrome (n = 2), hypersensitivity vasculitis (n = 1), oral contraceptives (n = 1), and hypertension (n = 3). Most patients received no treatment (62.5%, n = 140); however, by the last decade, 63.5% received some form of therapy. Operative repair was the most common therapeutic modality used (n = 40).
       More women died of SCAD than men (50.0 versus 24.6%; p < 0.001). Of the 161 women with SCAD, 48 (29.8%) were in the peripartum state (Table 1). Compared to men, women with SCAD were younger (40.4 versus 46.7%; p < 0.001) and were significantly less likely to have coronary artery disease (3.7 versus 20.6%; corrected p = 0.01 with the Bonferroni method). Men were more likely to have SCAD in the right coronary artery system than women (50.8 versus 13.0%; p = 0.01), and women had a higher proportion of left anterior descending artery involvement (46.6 versus 25.4%; p = 0.004) and left main artery involvement (14.9 versus 3.2%; p = 0.01). The circumflex artery was infrequently involved in men or women.
       Multivariate predictors of mortality in patients with SCAD are shown in Table 2. Female sex, the decade of occurrence, and failure to treat were independent predictors of death in this group. The significance of decade of occurrence likely relates to increasing antemortum diagnoses through cardiac catheterization. Although many women were pregnant or in the early postpartum period, this was not a predictor of increased mortality.
Conclusion. SCAD is an unusual diagnosis and is encountered more frequently in the age of angiography. The increase in the number of reported cases of SCAD due to more widespread use of cardiac catheterization is dramatic (Figure 2). Although our review did not directly implicate the increased use of angiography as the cause of improved outcomes for treatment of SCAD, it provides support for this hypothesis.
       Most episodes of SCAD occur in patients with no known risk factors. However, one risk factor — women in the peripartum state — stands out. Of women with SCAD, almost one-third were in the peripartum state. Furthermore, female gender was an independent predictor of mortality in the group of patients with SCAD. The diagnosis of SCAD must be suspected in peripartum women with an acute episode of chest pain. Other risks for SCAD are less specific and require a strong index of suspicion.
       Treatment options for SCAD have increased significantly, roughly paralleling the development of coronary angiography. These include medical therapy, percutaneous intervention, and coronary bypass. It is not possible to define the optimal treatment from our review. Of all the treatment options, no one option stands out as superior to the others. Our observations suggest that no matter what treatment is chosen, more than 95% of patients are likely to survive if the patient survives to the time of diagnosis.
       Nevertheless, there are limitations in this review. First, as with most case reviews, there is no comparison group, limiting the ability to derive associations. Second, other important information, such as physician specialty, smoking, and medication use, were not consistently reported and could not be used in the analysis. Finally, case reports exclude unknown cases of SCAD. With improvements in diagnosis over time, this may particularly affect earlier cases and influence estimates of survival and treatment outcomes. It is unlikely that evidence-based information about the best methods of diagnosis and treatment of SCAD will become available because of the rarity of this condition and the expense and time required to gather randomized, controlled data. In the meantime, retrospective reviews of the sort presented here are the best means of gaining insights into this disease process.
       In summary, SCAD is a rare clinical condition that is more common in women, especially in the peripartum state, and is readily diagnosed and treated with conventional options. Treatment options, including medical therapy, CABG and percutaneous interventions are likely to be successful in the great majority of patients.

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