When to stress patients after coronary artery bypass surgery? Risk stratification in patients early and late post-CABG using stress myocardial perfusion SPECT: Implications of apppropriate clinical strategies

OBJECTIVES The study compared the prognostic significance of myocardial per fusion single-photon emission computed tomography (SPECT) (MPS) in patients early and late after coronary artery bypass graft surgery (CABG). BACKGROUND The long-term effectiveness of CABG is limited by graft stenosis . The greatest incidence of graft occlusion occurs between five and eight y ears after surgery. However, little is known regarding the appropriate time to stress patients post-CABG with respect to risk stratification. METHODS We identified 1,765 patients, who underwent MPS 7.1 +/- 5.0 years p ost-CABG. All patients underwent rest T1-201/stress Tc-99m sestamibi MPS an d were followed up greater than or equal to1 year after testing. Patients w ith early CABG or PTCA (<60 days after MPS) were censored. The prognostic p opulation consisted of 1,544 patients. A semiquantitative visual analysis e mploying a 20-segment model was used to define summed stress score (SSS), s ummed rest score (SRS), summed difference score (SDS), and the number of no nreversible segments (NRS). RESULTS During follow-up, 53 cardiac deaths (CD) occurred. There was a sign ificant increase in annual CD rates as a function of SSS. A multivariate an alysis identified age, ischemia (SDS), and infarct size (NRS) as independen t predictors of CD. Nuclear variables added incremental value to prescan in formation. The annual CD rate was relatively low (1.3%) in patients <less t han or equal to>5 years post-CABG. In this subgroup only age and infarct si ze (NRS) were predictive of CD. CONCLUSIONS MPS is strongly predictive of subsequent CD in post-CABG patien ts and adds incremental value over clinical and treadmill test information. Our data suggest that symptomatic patients less than or equal to5 years an d all patients >5 years post-CABG may benefit from testing. (J Am Coil Card iol 2001;37:144-52) (C) 2001 by the American College of Cardiology.