Objective: To determine the prognostic value of myocardial ischemia, function and coronary risk factors on total and hard cardiac events using myocardial perfusion imaging in a Japanese population.
Methods: A prospective cohort study was performed in 117 Japanese hospitals, each with a nuclear cardiology facility. A total of 4,031 patients with suspected or confirmed ischemic heart disease were registered. The patients were followed up for a year to investigate total and hard events, and those who had any events were followed up for 3 years to evaluate subsequent hard events. A stress-rest gated myocardial perfusion study was performed with (99m)Tc-tetrofosmin using gated single-photon emission computed tomography (SPECT) and analyzed by semi-quantitative scores.
Results: During the 1-year follow-up period, 263 (6.5%) patients had total events comprising all-cause death, non-fatal myocardial infarction (MI), heart failure, unstable angina, angina pectoris and coronary revascularization. Cardiac death occurred in 23 patients (0.6%) and non-fatal MI in 11 (0.3%). Among patients with ejection fraction (EF) of <45% and a summed difference score (SDS) of >/=2, 18.7% (2.4% for cardiac death and 0.6% for non-fatal MI) experienced total events compared with 3.9% (0.3% for cardiac death and 0.2% for non-fatal MI; P < 0.0001) of those with EF >/= 45% and SDS < 2. Multivariate analysis identified EF, SDS, age, history of revascularization and diabetes as significant predictors of all events, while the significant predictors were age and EF for hard events. When the patients who had heart failure in the first year were followed up, 9 of 41 (22.0%) experienced cardiac death in the subsequent 3-year follow-up period.
Conclusions: Myocardial ischemia defined by SDS and ventricular function were the main predictors of total events despite the relatively low incidence of hard events in this Japanese population. In patients with cardiac events in a year, closer attention should be paid to subsequent hard events particularly in patients with heart failure.