Prediction of myocardial infarction versus cardiac death by gated myocardial perfusion SPECT: Risk stratification by the amount of stress-induced ischemia and the poststress ejection fraction

The combination of myocardial perfusion and poststress ejection fraction (E F) provides incremental prognostic information. This study assessed predict ors of nonfatal myocardial infarction (MI) versus cardiac death (CD) by gat ed myocardial SPECT and examined the Value of integrating the amount of isc hemia and poststress EF data in risk stratification. Methods: We identified 2,686 patients who underwent resting Tl-201/stress (99)mTc-sesta-mibi gate d SPECT and were monitored for >1 y. Patients who underwent revascularizati on less than or equal to 60 d after the nuclear test were censored from the prognostic analysis. Visual scoring of perfusion images used 20 segments a nd a scale of 0-4. Poststress EF was automatically generated. Results: Cox regression analysis showed that after adjusting for prescan data, the most powerful predictor of CD was poststress EF, whereas the best predictor of M I was the amount of ischemia (summed difference score [SDS]). Integration o f the EF and SDS yielded effective stratification of patients into low-, in termediate-, and high-risk subgroups. Patients with EF >50% and a large amo unt of ischemia were at intermediate risk (2%-3%), whereas those with mild or moderate ischemia were at low risk of CD (<1%/y). Patients with EF betwe en 30% and 50% were at intermediate risk even in the presence of only mild or moderate ischemia. in patients with EF <30%, the CD rate was high (>4%/y ) irrespective of the amount of ischemia. Conclusion: Poststress EF is the best predictor of CD, whereas the amount of ischemia is the best predictor of nonfatal MI. Integration of perfusion and function data improves stratif ication of patients into low, intermediate, and high risk of CD.