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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.

UNLABELLED
The combination of myocardial perfusion and poststress ejection fraction (EF) provides incremental prognostic information. This study assessed predictors of nonfatal myocardial infarction (MI) versus cardiac death (CD) by gated myocardial SPECT and examined the value of integrating the amount of ischemia and poststress EF data in risk stratification.


METHODS
We identified 2,686 patients who underwent resting (201)Tl/stress (99m)Tc-sestamibi gated SPECT and were monitored for >1 y. Patients who underwent revascularization < or = 60 d after the nuclear test were censored from the prognostic analysis. Visual scoring of perfusion images used 20 segments and 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 MI was the amount of ischemia (summed difference score [SDS]). Integration of the EF and SDS yielded effective stratification of patients into low-, intermediate-, and high-risk subgroups. Patients with EF >50% and a large amount 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 between 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 stratification of patients into low, intermediate, and high risk of CD.