Abstract 4139203: Anatomical Variations in Coronary Arteries and Implications in Spontaneous Coronary Artery Dissection

Introduction: Spontaneous coronary artery dissection (SCAD) is a poorly understood cause of acute coronary syndrome (ACS), predominantly affecting young women and frequently related to acute stressors. It has been suggested that stress induced cardiomyopathy can cause dissection via mechanical distortion of the vessel at wall-motion hinge points. Whether specific coronary anatomic configurations also predispose to distortion and hence SCAD remains unknown. Hypothesis: Patients with left anterior descending (LAD) SCAD have a higher frequency of a “wrap around” (type IV - perfuses >25% of the inferior wall) LAD. Methods: Coronary angiograms of patients in the Mayo Clinic SCAD Registry were reviewed. Patients from functional angiogram registry with similar characteristics were used as controls. Patients with an LAD SCAD were compared to patients who never had an LAD SCAD. For identifying predictors of LAD SCAD, patients who never had an LAD SCAD were compared to patients that had an LAD SCAD as a recurrent event, but not as the initial presentation. Results: A total of 456 patients with SCAD (46±6 years; 96% women) were included. The control group consisted of 178 patients (44±7 years, 97% women). Type IV LAD was more common in the SCAD cohort (Figure 1), and patients in the LAD SCAD group had a higher proportion of type IV LAD when compared to non-LAD SCAD (47.6% vs 23.0% p < 0.001). Bifurcation involvement was also more frequent (48.6 vs 25.8%, p <0.001). Individual predictors of an LAD SCAD during follow-up were diagnosis of hypertension, peripartum SCAD, involvement of a bifurcation and type IV LAD. After multivariate analysis, only bifurcation involvement (OR 2.49, p = 0.01) and type IV LAD (OR 2.26, p = 0.02) remained as predictors of LAD SCAD during follow-up. In patients in whom the PDA perfused the apex (LAD I and II), PDA was more likely to be involved by SCAD (OR 6.17, p<0.001). There were no other differences in coronary distribution after stratifying by LAD types. Conclusions: Type IV LAD variant is more common in patients with LAD SCAD. This finding suggests that coronary anatomic variants predispose to SCAD and lend further support to the mechanical distortion hypothesis.