Reduced stress perfusion in myocardial infarction with nonobstructive coronary arteries

Abstract

Background: Myocardial infarction with nonobstructive coronary arteries (MINOCA) constitutes a working diagnosis. Early cardiovascular magnetic resonance imaging (CMR) is recommended, however cannot provide a diagnosis in 25% of MINOCA cases. A pathophysiological mechanism may be coronary microvascular dysfunction (CMD). Quantitative stress CMR perfusion mapping allows for quantification of myocardial perfusion, which may detect CMD in the absence of obstructive coronary artery disease. However, it is unknown if CMD is present post-convalescence in suspected MINOCA patients. Purpose: To evaluate the presence of CMD after convalescence in patients with suspected MINOCA. Methods: Patients from the multicenter Stockholm Myocardial Infarction with Normal Coronaries (SMINC) 2 study with a normal CMR scan 2-4 days after hospitalization, and healthy age- and sex-matched volunteers underwent stress CMR during long-term follow-up. Cardiovascular risk factors, medication and symptoms of myocardial ischemia measured by the Seattle Angina Questionnaire 7, were registered. Results: In total, 15 patients with suspected MINOCA (59±7 years old, 60% female), and 15 healthy age- and sex-matched volunteers, underwent CMR. Patients with suspected MINOCA had lower global stress perfusion (2.83±1.8 vs 3.53±0.7 ml/min/g, p=0.02). There was neither differences in other CMR parameters such as global rest perfusion and myocardial perfusion reserve, hemodynamic parameters nor cardiovascular risk factors except for higher statin use in the MINOCA patient group compared to volunteers. Conclusions: Global stress perfusion is lower in MINOCA patients with a normal initial CMR scan during follow-up, compared to age- and sex-matched volunteers, suggesting CMD as a possible pathophysiological mechanism in MINOCA.