Long-term prognosis of patients presenting with ST-segment elevation myocardial infarction with no significant coronary artery disease (from the HORIZONS-AMI trial)

The clinical features and prognosis of patients with ST-segment elevation myocardial infarction (STEMI) and no significant coronary artery disease (CAD) have not been well studied. We examined the outcomes of patients with STEMI in the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial according to the presence or absence of significant CAD. "No-CAD" was defined by the absence of any lesion with a diameter stenosis of ≥30% on quantitative coronary angiography of the baseline coronary angiogram. Of 3,602 patients, 127 (3.5%) had no-CAD. Of these, 86 (67.7%) had angiographically normal coronary arteries, and 41 (32.3%) had mild disease (diameter stenosis <30%). Eight patients had previously been treated with coronary artery bypass grafting. Compared to patients with CAD, patients with no-CAD were younger, had a lower body mass index, were more frequently black, had a lower prevalence of smoking and previous angina, and had a greater left ventricular ejection fraction. Cardiac enzymes were elevated in fewer patients with no-CAD than in those with CAD (63.2% vs 98.7%, p <0.001). At 3 years of follow-up, the patients with no-CAD versus CAD had lower rates of major adverse cardiovascular events (7.7% vs 22.2%, p = 0.002), net adverse clinical events (major adverse cardiovascular events or major bleeding not related to coronary artery bypass grafting, 12.5% vs 26.9%, p = 0.005), and postprocedure coronary revascularization (0% vs 19.5%, p <0.001). The differences in the rates of death or reinfarction, stroke, and major bleeding were not statistically significant. In conclusion, 3.5% of patients with STEMI had no significant CAD. The 3-year prognosis for these patients was favorable compared to that of patients with STEMI and with obstructive CAD.