Acute coronary syndrome without critical epicardial coronary disease: prevalence, characteristics, and outcome

Absence of significant epicardial coronary artery stenosis in patients with acute onset of chest pain and elevation of myocardial necrosis markers is occasionally observed. The aim of this study was to retrospectively analyze the clinical characteristics and the outcome of such patients.All patients with myocardial infarction (MI) but without significant coronary artery stenosis (≥50%) on angiography from May 2002 to April 2011 were compared with patients undergoing percutaneous coronary intervention due to non-ST-elevation MI (NSTEMI).Of 4311 consecutive patients with MI, 272 patients (6.3%) did not show significant coronary artery stenosis (group I) and were compared with 253 NSTEMI patients (group II). Younger age (61.9±14.0 vs 65.4±12.0 years; P=.003), female sex (49.3% vs 28.9%; P.001), less severe anginal symptoms (Canadian Cardiovascular Society class III/IV 41.9% vs 49.8%; P=.05), lower level of myocardial necrosis marker (1.9±6.7 vs 27.4±68.7 ng/mL [troponin], 3.3±4 vs 14.2±20 mmol/L [creatine kinase]; P.001 for both), and higher left ventricular ejection fraction (58.7%±12.6% vs 48.1%±12.4%; P.01) were associated with group I patients. At a mean follow-up of 22.3±22.9 months, all-cause and cardiac mortality was lower in group I patients (4.9% vs 14.3%; and 2.9% vs 10.1%; P.01, for both). Event-free survival was more frequent in group I patients (58.4% vs 28.8%; P.0001) and inversely related to the troponin level.Absence of significant coronary stenosis accounts for a minority of patients presenting with MI and is associated with a better outcome compared to patients with NSTEMI, and the prognosis is inversely related to the troponin level.