Work

Prognostic Impact of Infarct Size and Coronary Microvascular Function Via Cardiovascular Magnetic Resonance and Coronary Angiography‐Derived Index of Microcirculatory Resistance in Myocardial Infarction With Nonobstructive Coronary Arteries

Year: 2025

Type: article

Abstract: BACKGROUND: Infarct size (IS) and microvascular obstruction (MVO), measured by cardiovascular magnetic resonance, are key prognostic markers after myocardial infarction (MI). The index of microcirculatory resistance (IMR) predicts MVO and IS; however, its role in MI with nonobstructive coronary arteries (MINOCA) is unclear. This study explored the relationship between coronary angiography-derived IMR, MVO, and IS in true MINOCA and assessed the prognostic value of coronary microvascular dysfunction (CMD), IS, and MVO. METHODS: Patients with suspected MINOCA who completed cardiovascular magnetic resonance and coronary angiography-derived IMR were included. CMD was defined as coronary angiography-derived IMR >25, and IS as a percentage of left ventricular mass (IS%LV) measured by late gadolinium enhancement. True MINOCA was identified by cardiovascular magnetic resonance evidence of ischemia or infarction. Individuals with true MINOCA were divided into 3 groups: non-CMD and IS%LV <16.78%, CMD or IS%LV ≥16.78%, and CMD with IS%LV ≥16.78%. Follow-up for major adverse cardiovascular events was conducted. RESULTS: Of 317 patients, 102 had true MINOCA (91.2% non-ST-segment-elevation MI). CMD was similarly distributed across all suspected MINOCA. Coronary angiography-derived IMR did not predict MVO or IS among true MINOCA. Over a median 27 months, 33.3% of patients with true MINOCA experienced major adverse cardiovascular events, with a higher risk in patients with CMD or IS%LV ≥16.78%. Multivariate Cox analysis revealed that CMD combined with IS%LV ≥16.78% had a hazard ratio (HR) of 7.40 (95% CI, 1.94-28.23), and either CMD or IS%LV ≥16.78% had an HR of 8.77 (95% CI, 2.57-29.94), but MVO did not. Sensitivity analyses excluding ST-segment-elevation MI supported these findings. CONCLUSIONS: CMD with larger IS strongly predicts major adverse cardiovascular events in MINOCA, underscoring their utility in risk stratification, especially for non-ST-segment-elevation MI. REGISTRATION: URL: https://clinicaltrials.gov. Unique identifier: NCT06502899.

Source: Journal of the American Heart Association

DOI: 10.1161/jaha.125.043169