Spontaneous coronary artery dissection (SCAD) is a common cause of myocardial infarction (MI) in young and middle aged women. Recurrent MI in patients with previous SCAD has not been well studied. We sought to evaluate the clinical and angiographic characteristics of recurrent SCAD cases in our large cohort of prospectively followed SCAD patients.
Patients with SCAD are prospectively followed at Vancouver General Hospital and enrolled in our registries Non-Atherosclerotic Coronary Artery Disease registry and the Canadian SCAD study. Those who developed a recurrent MI from a second SCAD event were included in our cohort. Diagnosis was confirmed by 2 interventional cardiologists with expertise in SCAD. Detailed medical history, baseline demographics, angiographic results, and clinical details of index SCAD and recurrent events were recorded. We defined SCAD extension as angiographic extension of previously dissected coronary segment, and recurrent SCAD was defined as de novo spontaneous dissection.
Of the total 310 patients enrolled in our SCAD registries, we identified 43 patients with SCAD extension or recurrence, giving an overall incidence of 13.9%. Baseline characteristics of our cohort include mean age 48.9±8.4 years, 38/43 were women, 21/43 had hypertension and 32/43 had fibromuscular dysplasia. Nine patients had SCAD extension at median time of 5 (1-19) days. 34 patients had recurrent SCAD at median time of 1487 (107-6461) days after index SCAD event. All SCAD extension patients had worsening of index dissected segment, with 5/9 involving extension to adjacent segments. While all recurrent SCAD patients had de-novo dissections affecting coronary segments distinct from the index dissection.
SCAD extension occurred early within 30 days of initial presentation, with involvement of the same or adjacent coronary segments as the index SCAD lesion. Recurrent SCAD occurred late and affected new segments distinct from previously dissected segments. We postulate that arterial wall scarring of previously dissected segment renders such segment more resilient to further arterial disruption. Further prospective studies are required to confirm this hypothesis.