Incremental prognostic value of sequential imaging of single-photon emission computed tomography and coronary computed tomography angiography in patients with suspected coronary artery disease

Aims This study was conducted to investigate the incremental prognostic value of sequential use of single-photon emission computed tomography (SPECT) and coronary computed tomography angiography (CCTA) in patients with suspected coronary artery disease (CAD). Methods and results A total of 1295 patients with suspected CAD who underwent both CCTA and SPECT within 90 days was retrospectively reviewed in three cardiac centres. Cardiovascular events including cardiac death, non-fatal myocardial infarction, unstable angina, and late (> 90 days of imaging tests) revascularization were assessed. During the mean follow-up period of 795 +/- 566 days (median, 735 days), there were 109 events (8.4%). Perfusion defect on SPECT and significant stenosis (>= 50%) on CCTA were independent predictors for events. Sequential use of both imaging tests significantly improved prediction of the cardiovascular events. The incremental prognostic value of SPECT was significant in patients with stenosis of <90% but not in patients with stenosis of >= 90% on CCTA. Similarly, the incremental prognostic value of CCTA was significant in patients with the summed stress score (SSS) <4 but not in patients with SSS >= 4 on SPECT. Conclusions Sequential use of SPECT and CCTA showed an incremental prognostic value in patients with suspected CAD. However, additional benefits were not significant when CCTA revealed stenosis of >= 90% or SPECT revealed SSS >= 4. These results suggest an effective risk stratification strategy for sequential use of SPECT and CCTA, and maximizing the benefits in these patients.