Population-Based Study of the Use of Cardiac Stress Imaging and Referral for Coronary Angiography and Repeated Revascularization After Coronary Artery Bypass Graft Surgery

Abstract

ObjectiveTo assess stress single-photon emission computed tomography (SPECT) and stress echocardiography use after coronary artery bypass grafting (CABG) and their effect on referral for coronary angiography and revascularization. Patients and MethodsThe referral, timing, and results of stress imaging after CABG; referral for coronary angiography and revascularization; and all-cause mortality were assessed in this longitudinal, population-based, retrospective study of 1138 Olmsted County, Minnesota, patients undergoing CABG between January 1, 1993, and December 31, 2003. ResultsA total of 570 patients (50.1%) underwent a stress imaging study (341 SPECT and 229 echocardiography) during the study period. Of the 1138 patients, 372 (32.7%) were referred for coronary angiography, and 144 of those patients (12.7%) underwent repeated revascularization (132 percutaneous revascularization and 12 CABG). The median interval between CABG and the index stress imaging study was 3.0 years (25th-75th percentile, 1.2-5.7 years). The results of 75.7% (258 of 341) of the stress SPECT studies and 70.7% (162 of 229) of the stress echocardiograms were abnormal. Seventy-six of 570 patients (13.3%) referred for stress imaging underwent coronary angiography within 180 days after the stress test. Repeated coronary revascularization was performed in 25 patients (4.4%) who underwent a stress imaging study within the preceding 180 days. The 5- and 10-year survival rates in the entire study cohort (83.5% and 65.1%, respectively) were not significantly different than predicted for the age- and sex-matched Minnesota population. ConclusionHalf of this community-based population of patients with CABG underwent stress SPECT or echocardiography during median follow-up of 8.9 years. Despite that approximately 75% of the results of stress imaging studies were abnormal, subsequent referral for coronary angiography within 180 days was low (13.3%), and the yield for repeated revascularization was very low (4.4%).