Prognostic value of normal stress myocardial perfusion imaging in Japanese population a study based on the J-ACCESS study

Background In Japan, Diagnosis Procedure Combination (DPC) of hospitalization health-care costs has been introduced since 2004, and its introduction has been recently expanded also to general hospitals. In such situations, the role of nuclear cardiology as a gatekeeper for the diagnosis of ischemic heart disease is increasingly important. Thus, the present study was designed to determine which clinical risk for hard events after normal single-photon emission computed tomography (SPECT) images, identify the predictors of increased risk in patients with normal SPECT images based on the J-ACCESS study. Methods and Results A total of 4,629 consecutively tested patients who underwent stress Tc-99m-tetrofosmin SPECT at hospitals in Japan were included in the study. Based on SPECT image data, 1,862 participants had a summed stress score of : 3, which was considered normal (selection criteria 1; normal perfusion). Myocardial perfusion was normal in 46.2% of the study population. Among normal SPECT subjects, cardiac function, as assessed by quantitative gated SPECT software, showed 1,786 participants were considered normal, based on left ventricular end-systolic volume (ESV) (ESV <= 60ml in men, ESV <= 40ml in women), which is defined as selection criteria H (normal perfusion and ESV). In addition, 1,742 participants were found to be normal based on ejection fraction (EF) (EF >= 49% in men, EF >= 55% in women), which is defined as selection criteria III (normal perfusion, ESV and EF). During the 3-year follow-up period, there was a total of 211 cardiac events (11.3%) in patients grouped in selection criteria 1, 196 cardiac events (11.0%) in patients grouped in selection criteria 11, and 189 cardiac events in patients grouped in selection criteria 111 (10.8%). The annual hard event rates were 0.81 %, 0.67% and 0.63% in selection criteria I, II and III, respectively. Cox proportional hazard analysis showed that diabetes mellitus, age and hypertension were independent predictors of all cardiac events in all selection criteria. Conclusion Normal stress myocardial perfusion imaging in the Japanese population is associated with a low cardiac event risk. The prognosis results of a normal SPECT scan would be useful for better patient management.