Prognostic utility of stress perfusion cardiac magnetic resonance in patients with known or suspected coronary artery disease and inconclusive exercise stress testing

Background Although exercise stress testing (EST) is commonly used for risk stratification in coronary artery disease (CAD), it yields inconclusive results in up to 20% of patients. Stress perfusion cardiac magnetic resonance (CMR) is a comprehensive and accurate tool for evaluating CAD, but data on its use in patients with inconclusive EST results are limited. Therefore, this study aimed to assess the prognostic value of stress perfusion CMR in patients with inconclusive EST results. Methods Consecutive patients with known or suspected CAD and inconclusive EST results who were referred for stress perfusion CMR between 2009 and 2022 were studied. Patients were divided into two groups based on the presence or absence of inducible myocardial ischaemia, as determined by CMR. The primary outcome was major adverse cardiovascular events (MACE), defined as a composite of cardiovascular death, acute coronary syndrome, hospitalisation for heart failure, and ischaemic stroke. Results A total of 414 patients (mean age 63±9 years, 48% male) were included, of whom 69 had myocardial ischaemia. Over a median follow-up of 6.9 years (IQR 4.5–9.9), 32 patients (7.7%) experienced MACE. Patients with myocardial ischaemia had a significantly higher annualised MACE rate than those without ischaemia (2.8 vs 0.8 per 100 patient-years, p<0.001). On multivariable analysis, myocardial ischaemia was an independent predictor of MACE (HR 4.03, 95% CI 1.94 to 8.38, p<0.001), along with atrial fibrillation (HR 5.83, 95% CI 1.69 to 20.09, p=0.005) and resting systolic blood pressure (HR 1.02, 95% CI 1.005 to 1.04, p=0.01). Subgroup analysis demonstrated a consistent association between myocardial ischaemia and increased MACE risk across most subgroups (all p for interaction >0.05). Conclusions Stress perfusion CMR demonstrated prognostic value and effectively stratified risk in patients with known or suspected CAD who had inconclusive EST results. Stress perfusion CMR represents a valuable tool for this patient population.