Prognostic value of myocardial perfusion abnormalities for long-term prognosis in patients after coronary artery bypass grafting

AIMS: The objective was to evaluate the prognostic value of exercise myocardial perfusion scintigraphy (MPS) in patients who underwent coronary artery bypass grafting (CABG). SUBJECTS AND METHODS: A retrospective, one-center study of 361 patients with multivessel coronary artery disease was carried out. All the patients underwent MPS after CABG due to worsened health status. MPS was performed at 4.5 years standard deviation (SD: 0.2), based on symptoms. MPS was carried out using Tc-99m methoxy isobutyl isonitrile and following a 1-day protocol (stress-rest). The end points were analyzed at 6.5 years (SD: 3.3) after MPS, on the average. STATISTICAL ANALYSIS USED: SPSS software for Windows, version 13.0. The t-test or the χ(2)-test was used. Survival times were calculated. A multivariate Cox proportional hazards model was developed. RESULTS: During the follow-up, death occurred in 54 patients, and 37 patients experienced major adverse cardiovascular events (MACE). In the multivariate analysis, advanced age hazard ratio (HR: 1.45; 95% confidence interval [CI]: 1.4–2.02; P = 0.027), previous myocardial infarction (HR: 3.17; 95% CI: 1.22–8.2; P = 0.018), left ventricular ejection fraction of <40% (HR: 2.16; 95% CI: 1.2–3.89; P = 0.01), and the summed stress score (SSS) of ≥4 (HR: 1.87; 95% CI: 1.02–3.41; P = 0.04) were independent predictors of all-cause death. The summed difference score (SDS) was the only independent predictor of MACE (HR: 1.26; 95% CI: 1.06–1.48; P = 0.034). CONCLUSIONS: The parameters of MPS were found to have prognostic value in the long-term period after CABG. Advanced age, previous myocardial infarction, decreased left ventricular ejection fraction, and the abnormal SSS were associated with an increased risk of all-cause death. The SDS was found to be the only significant risk factor for MACE.