Predictive role of non-hyperemic angiography-derived index of microcirculatory resistance in patients with myocardial infarction with non-obstructive coronary artery disease

Abstract Background Myocardial infarction with non-obstructive coronary artery disease (MINOCA) is a heterogeneous condition requiring cardiac magnetic resonance (CMR) to confirm its ischemic etiology. The coronary angiography-derived non-hyperemic index of microcirculatory resistance (NH-IMRangio) has shown strong correlation with invasive IMR and carries prognostic value in patients with acute coronary syndromes. This study aimed to evaluate the relationship between coronary microvascular dysfunction (CMD), assessed by NH-IMRangio, and the presence of an ischemic pattern on CMR in patients with MINOCA. Methods This multicenter, prospective study included 68 MINOCA patients who underwent CMR within 7 days from hospital admission (early CMR). NH-IMRangio was analyzed in the left anterior descending artery by an independent core laboratory. Using the Youden index, the optimal NH-IMRangio cut-off to predict an ischemic pattern on CMR was determined, dividing patients into low 32 (47%) and high 36 (53%) NH-IMRangio groups. Logistic regression was used to identify predictors of ischemic patterns on CMR. Results The study cohort (n=68) had a median age of 60 years 51–72, with 60.3% being female. ROC analysis showed NH-IMRangio was a predictor of ischemic patterns on CMR (AUC 0.68, 95% CI 0.55–0.81, p=0.007), with an optimal cut-off of NH-IMRangio90 U. Patients with high NH-IMRangio more frequently presented with typical angina at admission, higher peak troponin levels, and regional wall motion abnormalities on echocardiography. On CMR, high NH-IMRangio was associated with a greater prevalence of ischemic late gadolinium enhancement (LGE) patterns (69% vs. 31%, p=0.002), particularly with subendocardial distribution in the anterior region (p=0.020), corresponding to the analyzed vessel. Furthermore, microvascular obstruction was more common in the high NH-IMRangio group. Conversely, patients with low NH-IMRangio more often exhibited normal CMR findings (p=0.033) or pathological findings suggestive of myocarditis (p=0.031). After adjusting for confounding factors, NH-IMRangio emerged as an independent predictor of ischemic pattern on CMR. Conclusions NH-IMRangio may serve as a predictor of ischemic pattern on CMR in MINOCA patients. These findings highlight its potential clinical utility in identifying coronary microvascular dysfunction in this patient population, aiding the selection of patients eligible to undergo an early CMR and/or invasive functional assessment.CMD to Clinical-CMR findigs correlation