Abstract 105: Rehospitalization After Admission With Myocardial Infarction and Spontaneous Coronary Artery Dissection

Introduction: Spontaneous coronary artery dissection (SCAD) is one of the most common non-atherosclerotic causes of myocardial infarction (MI) in young patients, yet little is known about post-discharge outcomes. Given the high psychological stress of a SCAD diagnosis, we sought to understand the rehospitalization burden after SCAD so as to provide more prognostic data to SCAD patients.

Methods: Using data from the Nationwide Readmission Database 2010-16, we identified patients 18-55 years of age hospitalized with MI with and without SCAD. We compared readmission over 1 year after index hospitalization for all-cause, MI, chest pain without MI, and heart failure. Cox proportional regression was used to examine factors associated with readmission, and we explored interactions of patient factors*SCAD to identify factors associated with differential risk of readmission in patients with SCAD.

Results: Among 327,227 young patients admitted with an MI, 3704 (1.1%) had a diagnosis of SCAD. Patients with SCAD were more likely to be younger, women, have a higher burden of anxiety or depression, and longer length of stay compared with those without SCAD. While the risk of all-cause rehospitalization over 1 year was similar in those with versus without SCAD (KM-estimated rates: 22.3% vs. 24.1%; log-rank p=0.596, Figure), patients with SCAD were more likely to be rehospitalized for MI (4.9% vs. 4.2%, log-rank p=0.012) and chest pain without MI (3.6% vs. 2.8%, log-rank p=0.060) but less likely to be rehospitalized for heart failure (1.0 % vs. 1.8%, log-rank p=0.005). In the multivariable model, a diagnosis of SCAD was not associated with risk of rehospitalization (HR 1.00, 95% CI 0.92-1.08) nor was a diagnosis of SCAD associated with a differential effect of any of the patient factors on the risk of rehospitalization (all interaction p-values >0.05).

Conclusion: Although patients with SCAD had a similar risk of rehospitalization compared with young patients with MI but without SCAD, we identified different patterns of hospitalization, which may be explained by the different underlying conditions. Further studies are needed to investigate possible interventions to reduce the high burden of post-SCAD rehospitalizations.