Long-Term Warranty Period of Stress CMR and SPECT in Stable Angina: Implications for Repeat Testing

Background Few prospective studies have explored the long-term prognostic value and warranty period of functional imaging in patients with stable chest pain. The CE-MARC (Clinical Evaluation of Magnetic Resonance in Coronary Heart Disease) trial recruited 752 patients with suspected angina and demonstrated the high diagnostic accuracy of stress cardiac magnetic resonance (CMR) compared with single-photon emission computed tomography (SPECT), using invasive coronary angiography as the reference standard. Objectives This study aims to assess the comparative long-term prognostic value of stress CMR and SPECT and to establish operational warranty periods for normal test results. Methods Participants in the CE-MARC trial were followed up for major adverse cardiovascular events (MACE), including cardiovascular death, myocardial infarction, and unplanned coronary revascularization. The warranty period identified the time interval during which patients with a normal test result remained 97.5% free of MACE. Multivariable regression analysis identified key warranty period modifiers. Results Of 752 recruited patients, 652 (86.9%) with CMR and SPECT with follow-up available formed the study cohort. At a median of 15.5 years (Q1-Q3: 12.4-16.6 years), 40 (6.1%) cardiovascular deaths occurred, 29 (4.4%) patients experienced a myocardial infarction, and 47 (7.2%) unplanned revascularization. After adjustment for cardiovascular risk factors, an abnormal CMR remained a strong independent MACE predictor (HR: 2.74; 95% CI: 1.70-4.42; P < 0.001). Patients with a normal test result had a warranty period of 6.8 years for stress CMR and 5.1 years for SPECT. Age, smoking, and diabetes identified higher-risk patients who had a reduced warranty period for a normal result. Conclusions In a long-term prospective study of patients with stable chest pain, stress CMR remained a strong, independent predictor of hard cardiovascular events, with a warranty period of almost 7 years for a normal scan. (Clinical Evaluation of Magnetic Resonance in Coronary Heart Disease; [CE-MARC]; ISRCTN77246133)