Usefulness of stress cardiac single-photon emission computed tomographic imaging late after percutaneous coronary intervention for assessing cardiac events and time to such events

This study assessed the predictors and temporal characteristics of cardiac risk in patients undergoing stress single-photon emission computed tomography (SPECT) after percutaneous coronary intervention (PCI). Stress SPECT was performed in 346 patients 12 to 18 months after PCI. Cardiac death and myocardial infarction were considered events. Cox proportional hazards analysis was used to identify predictors of events and parametric survival analysis to predict time to events. During follow-up (31 +/- 10 months), 17 events occurred (4.9% cumulative event rate). Prescan likelihood of ischemia and ischemia at SPECT were independent predictors of events (p <0.001). Cumulative probabilities of event-free survival were 88% in patients with ischemia at SPECT and 98% in those without (p <0.001). Patients without ischemia at SPECT were at low probability of failure and times to achieve > or =2% risk of events were >48 months in those with low prescan likelihood of ischemia and >20 months in those with intermediate to high prescan likelihood. Ischemia at SPECT was associated with higher probability of failure accelerating over time. In conclusion, clinical variables and stress SPECT performed 12 to 18 months after PCI are useful to characterize risk of cardiac events and its temporal variation. Parametric survival models seem useful to estimate predicted time to risk and levels of risk at specific intervals after PCI.