Association between coronary artery calcium score and myocardial ischemia assessed by stress perfusion cardiac magnetic resonance imaging

BACKGROUND: Coronary artery calcium (CAC) scoring effectively stratifies cardiovascular risk, and stress perfusion cardiac magnetic resonance (CMR) accurately detects myocardial ischemia. We aimed to investigate the prevalence and factors associated with myocardial ischemia on CMR in patients with CAC, and to assess the clinical impact of myocardial ischemia following CMR. METHODS: This study included 215 patients aged ≥18 years who underwent CAC scoring for risk stratification, followed by stress CMR between 2013 and 2026. The prevalence and predictors of myocardial ischemia were investigated. Receiver operating characteristic (ROC) analysis was performed to assess the association between CAC scores and myocardial ischemia. Additionally, subsequent clinical management following CMR was determined. RESULTS: The mean age was 69.3 ± 9.1 years (60.9% male). The average 10-year PREVENT risk score was 18.6 ± 8.7%. Overall, myocardial ischemia was present in 26.0% of patients (56/215): 17.1% in the CAC 300-999 Agatston units (AU) group (14/82) and 41.6% in the CAC ≥ 1,000 AU group (42/101). CAC score was the only independent predictor of myocardial ischemia (adjusted OR 1.07, 95%CI 1.03 - 1.10; p < 0.001 per 100 AU). Across clinical risk score categories and diabetes status, CAC score was consistently associated with myocardial ischemia, with no significant interactions observed (all p for interaction >0.05).The number of ischemic segments increased with increasing CAC scores (p < 0.001). ROC analysis demonstrated an optimal cutoff threshold of CAC ≥ 1,093 AU for detecting myocardial ischemia (AUC 0.75, p < 0.001). The clinical impact of stress CMR included medication changes in 37.2% of patients, while 18.1% underwent invasive procedures. CONCLUSIONS: In patients with CAC scores undergoing stress CMR, the prevalence of myocardial ischemia was approximately one-fourth and was associated with higher CAC scores. Stress CMR may influence clinical management in this population. Larger or prospective studies validating these findings and evaluating prognosis are warranted.