A Study on Patients Presenting Like Acute Coronary Syndrome in the Absence of Obstructive Coronary Artery Disease on Coronary Angiogram

Introduction: Particular interest has been raised in mechanisms of acute coronary syndromes (ACS) that cannot be explained by the presence of obstructive coronary atherosclerosis. Our study strived to find the prevalence, clinical profile, etiology and short term prognosis amongst patients without significant obstructive coronary artery disease (CAD) presenting like ACS to a tertiary care hospital of Eastern India. Methods: The study was a hospital based observational, descriptive longitudinal study on 968 patients with chest pain suggestive of ACS at the time of presentation. Result: Among the consecutive 968 patients, 63 were found to have non-obstructive lesion in coronary angiography (CAG), of which 23.8% were with normal coronaries and 76.2% with minor/mild CAD. Except for hypertension, there was no significant difference in prevalence of the conventional risk factors like smoking, dyslipidaemia, and diabetes mellitus between these two groups. Coronary vasospasm (9%), myocardial bridge (8%), spontaneous dissection and ectasia (3% each) and abnormal origin (2%) were the other findings. Slow flow was most common (68%) in STEMI subgroup. The Kaplan - Meier survival curve analysis showed significant difference in terms of MACE free survival (p = 0.04) between two groups but not in terms of overall death (p = 0.68). Univariate analysis showed regional wall motion abnormality and arrhythmia as significant predictor of major adverse cardiac events (MACE) remains. Conclusion: Non - obstructive CAD in patients with ACS remains uncommon finding. The conventional risk factors are not significantly different in subgroup analysis except hypertension and there was significant difference in terms of MACE free survival in these patients.