Myocardial Infarction in a Non-Obstructive Coronary Artery (MINOCA): A Ten-Year Makati Medical Center Experience.

BACKGROUND: Myocardial infarction with non-obstructive coronary arteries (MINOCA) is defined as cases of acute myocardial infarction (MI) without angiographic evidence of obstructive coronary artery disease (CAD). The underlying pathophysiological mechanisms of MINOCA is poorly understood and it is also unclear whether these patients have the same clinical outcomes as those with coronary obstruction. Currently, there are no published reports on the prevalence of MINOCA in the Philippines. This study aimed to determine the prevalence of MINOCA in patients admitted at the Makati Medical Center from 2007 to 2017 and to elucidate its most common causes.

METHODS: This study was a cross-sectional analytical study conducted at the Makati Medical Center, which screened all patient charts and records of admitted patients with STEMI who had a coronary angiogram from November 01, 2007 to October 31, 2017. Sample size was computed, and simple random sampling using a computer-generated random list was performed to generate the list of final study participants. After ensuring completeness and accuracy, demographic and clinical data from these patients were collected; no direct patient contact occurred during the study. The prevalence of MINOCA was determined, and data were statistically analyzed using STATA 15.

RESULTS: From 6,632 patients, admitted from 2007 to 2017, who had coronary angiogram, 576 had an emergency procedure. From these patients, 363 patients were chosen by random sampling and were identified as study participants. MINOCA had a prevalence of 8%, with 92% of cases presenting as CAD. MINOCA tended to affect younger patients (47 years vs 57 years, p <0.001), was more common in females (38% vs 15%, p=0.0002) and was less likely to present with hypertension (21% vs 68%, p<0.0001). No significant difference was found between the MINOCA group and CAD group with regard to traditional comorbidities and risk factors, pharmacologic management and in-hospital mortality

CONCLUSION: This study demonstrated that MINOCA is not uncommon in patients with ST elevation MI over the ten-year period. It should be recognized that MINOCA is a heterogeneous entity with diverse underlying pathophysiologic causes, and more research is needed to identify diagnostic modalities to explain its underlying mechanism and to provide appropriate treatment.