Dual isotope myocardial SPECT, rest thallium-201/dipyridamole stress Tc-99m sestamibi is used to diagnose coronary artery disease. We examined predictive value of myocardial SPECT for the prognosis of patients having or suspected coronary artery disease.

We examined 692 patients referred for dipyridamole stress myocardial perfusion SPECT. Cardiac events (hard and soft events) were followed up with medical record review and telephone interview. Survival analysis and multivariate Cox proportional hazard model were used to find significant predictors and the incremental predictive value of myocardial SPECT. Patients with coronary angiography (n=246) were analyzed in separate group.

There were 4 hard events and 3 soft events in 341 normal SPECT group (1.20%/yr). There were 5 hard events and 21 soft events in 351 abnormal SPECT group (4.69%/yr). Survival curve was separated between normal SPECT group and abnormal SPECT group (p<0.01). In univariate analysis, smoking, history of myocardial infarction, typical chest pain and SPECT findings were important variables. In multivariate analysis, SPECT result was the single most independent predictor. Large reversible perfusion abnormality predicted worse prognosis. In patients with coronary angiography, SPECT did not add statistically significant predictive value to the coronary angiography.

Dipyridamole stress Tl-201/ MIBI dual isotope myocardial perfusion SPECT provided excellent prognostic information. Extent of reversible perfusion decrease was the independent predictor of future cardiac events.