Abstract Body (Do not enter title and authors here): Myocardial infarction with nonobstructive coronary artery disease (MINOCA) is an ischemic cause of chest pain with normal appearing coronary vessels on angiography. The prognosis for these patients is extremely dependent on etiology highlighting the importance for appropriate evaluation. Currently, several imaging modalities have been useful in diagnostic workup, however no diagnostic guidelines have been developed. As a result, many patients are likely not getting proper evaluation. The study's main objective is to observe practice variations in the diagnostic evaluation for patients meeting criteria for MINOCA.

A review of electronic medical records of patients presenting to a tertiary care center between Jan 2018 – Dec 2022 for chest pain who were referred for left heart catheterization was performed. Patients with prior history of obstructive CAD, whose imaging evaluation uncovered obstructive stenosis or had stenosis >50% as measured on LHC were excluded. Next, patients diagnosed with a nonischemic cause of hospital presentation were excluded. Examples of nonischemic etiologies include stress induced cardiomyopathy, myocarditis and pulmonary embolism. Data regarding medical management and follow-up imaging were collected.

A total of 2,763 patients were reviewed. Among them, 168 patients met the exclusion criteria. Approximately 60% (n=101) of patients were female with an average age of 60 years. Medical management with aspirin (n=123), DAPT (n=22), beta-blocker (n=98), calcium channel blocker (n=58), statin (n=130), anti-anginal therapy (n=55), diuretics (n=47), and ACEi/ARB (n=69) were observed. Additional imaging was seen in only 26% of patients. The imaging modalities used were cardiac MRI (cMRI), fractional flow reserve (FFR) and intravascular ultrasound (IVUS). The most common imaging modality was cMRI (n=35), followed by FFR (n=8) and IVUS (n=1).

MINOCA was identified in 6% of patients presenting with AMI and was primarily comprised of women, which is consistent with other reported figures. Our data demonstrates that nearly 75% of these patients were placed on medical therapy without further evaluation. MINOCA is a diagnosis with multiple pathophysiological etiologies that requires thorough workup including additional imaging for complete evaluation. This study demonstrates the importance of considering MINOCA as a potential diagnosis in patients presenting with AMI and the need for guidelines on its evaluation.