Differences in revascularization strategy and outcomes in ST-elevation and non-ST-elevation myocardial infarction with spontaneous coronary artery dissection

Background Spontaneous coronary artery dissection (SCAD) is an important cause of myocardial infarction (MI) in young to middle-aged women. However, the role of revascularization for SCAD, especially percutaneous coronary intervention (PCI), remains controversial. Purpose To compare revascularization strategies and outcomes in SCAD patients presenting with ST-elevation MI (STEMI) vs. unstable angina or non-STEMI (UA/NSTEMI). Methods We analyzed SCAD patients who presented acutely between June 2014 and June 2018 to 22 centers participating in the Canadian SCAD Cohort Study. We compared treatment patterns and clinical outcomes in SCAD patients with an initial clinical presentation of STEMI vs. UA/NSTEMI. We assessed follow-up major adverse cardiovascular event (MACE) rate, a composite of all-cause death, MI, and stroke. The impact of revascularization on MACE was also evaluated according to clinical presentations (STEMI vs. UA/NSTEMI). Results Among 750 SCAD patients (mean age 51.7±10.5 years; 88.5% were women), 234 (31.2%) presented with STEMI. In the STEMI group, left anterior descending artery was more commonly involved (62.0% vs. 47.5%, p<0.001) and TIMI 0 flow was more frequently observed (24.8% vs. 7.2%, p<0.001). A total of 27.8% of STEMI patients were treated with revascularization (98.5% PCI), whereas only 8.7% of UA/NSTEMI patients were revascularized (93.3% PCI). For STEMI patients, 93.9% were planned procedures, whereas, for UA/NSTEMI patients, 71.1% were planned revascularization. Successful or partially successful PCI was 65.5% for STEMI and 76.9% for UA/NSTEMI (p<0.001). The median follow-up period was 850 (interquartile range: 619–1096) days. MACE rate was not different between STEMI and UA/NSTEMI (UA/NSTEMI as a reference: hazard ratio [HR] 1.08, 95% confidence interval [CI] 0.70–1.68, p=0.72). Regardless of clinical presentations, revascularization was associated with increased risk of MACE (STEMI: HR 2.57, CI 1.25–5.25, p=0.01; UA/NSTEMI: HR 5.41, CI 3.19–9.19, p<0.001). The association of revascularization and increased risk of MACE was more prominent in UA/NSTEMI than in STEMI (Figure), but it did not reach statistical significant (P for interaction = 0.09). Conclusions In SCAD patients, long-term clinical outcome was not different between STEMI and UA/NSTEMI presentations. Revascularization was more frequently performed with STEMI; however, regardless of clinical presentations, revascularization was associated with worse clinical outcomes. Careful patient selection for revascularization is key for SCAD patients and further studies are needed to clarify selection criteria. Revasc and MACE by presentation Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Canadian Institutes of Health Research