Major cardiac event risk scores estimated with gated myocardial perfusion imaging in Japanese patients with coronary artery disease

Background: A Heart Risk Table has been reported as the first risk score based on nuclear cardiology to predict cardiac event rates in Japanese patients. However, there are no risk scores estimating risk of major cardiac events (MCEs) except severe heart failure. Methods: We retrospectively investigated 2579 patients with known or suspected coronary artery disease (CAD) who underwent rest ²⁰¹Tl and stress ^99mTc-tetrofosmin myocardial perfusion single photon emission computed tomography between October 2004 and March 2011 and who had data on a 3-year follow-up. The perfusion images were analyzed with 20 segments of a five-point visual scoring model to estimate summed defect scores. The endpoint was the onset of MCEs consisting of cardiac death, non-fatal myocardial infarction and unstable angina pectoris. Results: During the 3-year follow-up, 171 patients (6.6%) experienced MCEs comprising cardiac death (n = 78), non-fatal myocardial infarction (n = 30), and unstable angina pectoris (n = 63). The multivariate logistic regression analysis indicated age, diabetes, estimated glomerular filtration rate (eGFR), and summed stress scores (SSS) as independent predictors of the MCEs and age, stress ejection fraction, eGFR, and SSS as independent predictors of cardiac death. Those four predictors and coefficients corresponding to them were used to make two different risk equations: MCE risk (%/3 years) = {1/1 + Exp[-(-3.176 + 0.018 × age + 0.602 × diabetes - 0.022 × eGFR + 0.051 × SSS)]} × 100 and cardiac death risk (%/3 years) = {1/1 + Exp[-(-2.602 + 0.031 × age - 0.031 × eGFR + 0.038 × SSS - 0.029 × stress ejection fraction)]} × 100. Conclusion: The risk scores obtained from this study are useful to predict MCEs in Japanese patients with CAD and are expected to be useful for management and informed consent of high-risk CAD patients.