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 trial recruited 752 patients with suspected angina and demonstrated the high diagnostic accuracy of stress CMR against SPECT against a reference of invasive coronary angiography. Objectives 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 CE-MARC 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 where 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 15.5 years (IQR12.4–16.6), 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 high-risk patients in which the warranty period for a normal result was reduced. 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.