Outcome prediction in patients at high risk for coronary artery disease: comparison between 99mTc tetrofosmin and 99mTc sestamibi

Purpose: To determine if there was any difference in the ability of physicians to predict prognosis with technetium 99m ((99m)Tc) sestamibi or (99m)Tc tetrofosmin in a large consecutive series of patients at high risk for coronary artery disease who underwent coronary angiography.

Materials and methods: This study included 1,818 consecutive patients who underwent a rest and stress single photon emission computed tomographic (SPECT) examination with either (99m)Tc sestamibi (n = 915) or (99m)Tc tetrofosmin (n = 903) and cardiac catheterization. A clinical index was generated and consisted of clinical and demographic variables. Information concerning death, cardiovascular death, and nonfatal myocardial infarction was 93% complete during the 1.5-year study period. Cox proportional hazards models were generated to help determine the incremental contribution of SPECT sum stress score (SSS) and the imaging agent variable to the clinical index.

Results: Exercise was used for stress testing in 473 (52%) patients who received (99m)Tc tetrofosmin and 519 (57%) patients who received (99m)Tc sestamibi (P =.06). Cardiovascular death or myocardial infarction occurred in 130 patients. Resulting P values for chi(2) differences between models for the end points of (a) death from any cause, (b) cardiovascular death, and (c) cardiovascular death or myocardial infarction showed that SSS combined with clinical index was a significantly better model than adjusting for only baseline characteristics (P =.001, P <.001, P =.004, respectively). Incremental addition of either (99m)Tc tetrofosmin or (99m)Tc sestamibi to those models containing SSS and the clinical index did not show further significant improvement (P =.87, P =.88, and P =.26 for death from any cause, cardiovascular death, and cardiovascular death or myocardial infarction, respectively).

Conclusion: This study shows that the type of clinically available (99m)Tc-labeled myocardial perfusion agents should not affect interpretation of results for risk stratification and prognostic assessment.