Patients with non-obstructive coronary artery disease admitted with acute myocardial infarction carry a better outcome compared to those with obstructive coronary artery disease

Background The characterization of patients who have acute myocardial infarction (AMI) and insignificant coronary stenosis is unclear. Aim The present study aimed to investigate the clinical profile, in-hospital and 3-month outcome of AMI patients with insignificant coronary stenosis in comparison with those with significant disease. Methods This prospective observational study included 200 consecutive patients admitted with AMI. Group I (100 patients) included patients with insignificant CAD (all lesions <50% stenosis). Group II (100 patients) included patients with one or more lesions >70% stenosis. Patients with previous CABG were excluded. Patients with significant CAD had successful total revascularization. Results Patients with insignificant CAD were significantly younger (61 vs. 67 years, p < 0.001), more likely to be females (41% vs. 23%, p = 0.006), less likely to smoke (p = 0.006), less likely to have diabetes mellitus (p < 0.001), and less likely to have history of CAD (p = 0.042) or prior PCI (p = 0.037). They were also less likely to have typical anginal pain at presentation (61% vs 91%, p < 0.001), less likely to have heart failure at presentation (9% vs 30%, p < 0.001), less likely to have ischemic ST-segment changes on presentation (10% vs 46%, p < 0.001), lower peak troponin (p < 0.001) and CK-MB levels (p < 0.001), with lower LDL-C (p = 0.006), and higher HDL-C level (p = 0.020). They were less likely to be treated with b-blockers (p = 0.002), ACEI/ARBS (p = 0.007), and higher rates of calcium channel blocker therapy (p < 0.001). They had lower prevalence of major adverse clinical events at follow-up (readmission for ACS (p = 0.009), need for revascularization (p = 0.035), recurrent chest pain (p = 0.009), and cardiogenic shock (p = 0.029). Conclusion Patients with AMI and insignificant CAD have different clinical profile and outcome compared to those with significant disease.