Multi-modality Imaging to Determine Underlying Causes of MINOCA in Women and Men.

Abstract

BACKGROUND Myocardial infarction with non-obstructive coronary arteries (MINOCA) has several underlying causes, including mimicking conditions in some cases. Imaging is recommended to identify MINOCA etiologies, but it remains unclear which patients are most likely to have abnormal findings. We characterized MINOCA mechanisms, analyzed predictors of imaging abnormalities and explored sex differences. METHODS We enrolled patients with clinical diagnosis of MI in an international, prospective, diagnostic study at 28 sites in US, Canada and UK. After a women-only phase, we included both sexes. Individuals with ≥50% diameter stenosis or coronary dissection on angiography, or alternate causes for the clinical presentation, were excluded. Participants had multi-vessel coronary optical coherence tomography (OCT) during index coronary angiography and cardiac magnetic resonance imaging (CMR) within one week. Independent core laboratories interpreted imaging, blinded to other results. RESULTS Among 754 patients enrolled, 389 had MINOCA and 336 with MINOCA underwent OCT (270 women and 66 men); CMR was completed in 284 (85%). An OCT-defined culprit lesion was identified in 45% (116/270 women [43% ] and 35/66 men [53%], p=0.18). CMR demonstrated an ischemic pattern in 114/284 (40%), similar by sex (96/225 women [43%] vs. 18/59 men [31%], p=0.12). A non-ischemic pattern was observed in 23% (23% of women, 25% of men, p=0.78). We identified a cause of the clinical presentation in 79% of patients with both tests completed: 59% had an ischemic cause of MINOCA and 20% had a non-ischemic mimicking condition. OCT alone found a MINOCA etiology in 151/336 (45%) and CMR alone in 180/284 (63%). Predictors of an OCT culprit lesion included age, abnormal angiogram, and number of vessels imaged, but 27% of normal angiograms harbored a culprit lesion. Predictors of abnormal CMR were peak troponin, shorter time to CMR, and non-Asian race, but CMR was abnormal in 40% when troponin was <4-fold above the upper reference limit. CONCLUSIONS The combination of multi-vessel coronary OCT and CMR in patients with a clinical diagnosis of MINOCA confirmed MI in 59% and identified an alternate cause (MINOCA mimic) in 20%. Clinical factors had limited utility to predict imaging abnormalities. No sex differences in imaging results were detected.