Background: Multi-slice computed tomography coronary angiography (MSCT) and gated single photon emission computed tomography (SPECT) are both used for the detection of coronary artery disease (CAD). The purpose of this study was to investigate the prognostic value of both MSCT and SPECT in a large cohort of patients with known or suspected CAD. Methods: In 426 patients (63% male, age 61±11 years) referred for further cardiac evaluation, both MSCT and SPECT were performed. The following events were recorded: cardiac death, non-fatal infarction, unstable angina requiring hospitalization, and revascularization (> 60 days after imaging). Results: MSCT detected significant CAD (MSCT > 50% luminal narrowing) in 179 (42%) patients, while a perfusion defect (rest and / or stress) was observed in 164 (39%) patients. During a follow-up of 540 days, an event occurred in 38 (9%) patients. The annualized event rate in patients with a normal or non-obstructive MSCT was 3% versus 12% in patients with MSCT > 50%. Patients with a normal SPECT had an event rate of 3% versus 11 % in patients with an abnormal SPECT. The highest event rate (14%) was observed in patients with MSCT > 50% and an abnormal SPECT. Importantly, the event rate in patients with a normal SPECT but MSCT > 50% was 8% (Figure 1) (Log rank, p Conclusion: Both MSCT, which evaluates atherosclerosis, and SPECT, which detects ischemia, have an incremental prognostic value regardless of the outcome of the other examination. The current observations underline the complementary nature of both techniques.