Purpose: To determine the long-term prognostic value of dobutamine stress technetium 99m (99mTc)-labeled sestamibi single photon emission computed tomography (SPECT) in patients with limited exercise capacity.
Materials and methods: Clinical data and SPECT results were analyzed in 531 consecutive patients. Follow-up was successful in 528 (99.4%) patients; 55 underwent early revascularization and were excluded. Normal or abnormal findings were considered in the absence or presence of fixed and/or reversible perfusion defects. A summed stress score was calculated to estimate the extent and severity of perfusion defects. Univariate and multivariate Cox proportional hazards regression models were used to identify independent predictors of late cardiac events. The incremental value of myocardial perfusion scintigraphy over clinical variables in predicting events was determined according to two models. The probability of survival was calculated by using the Kaplan-Meier method.
Results: Findings were abnormal in 312 patients. During 8.0 years +/- 1.5 of follow-up (range, 4.5-10.6 years), cardiac death occurred in 67 patients (total deaths, 165); nonfatal myocardial infarction, in 34; and late revascularization, in 49. The annual rates for cardiac death, cardiac death or infarction, and all events were 0.9%, 1.2%, and 1.5%, respectively, after normal findings and 2.7%, 3.4%, and 4.4%, respectively, after abnormal findings (P <.05). In a multivariable Cox proportional hazards model, not only an abnormal finding but also the summed stress score provided incremental prognostic information in addition to clinical data. The hazard ratio for cardiac death was 1.09 (95% CI: 1.01, 1.18) per 1-unit increment of the summed stress score.
Conclusion: The incremental prognostic value of dobutamine stress 99mTc-sestamibi SPECT over clinical data was maintained over an 8-year follow-up in patients with limited exercise capacity.