Surgical aspects of a randomized trial of defibrillator implantation during coronary artery bypass surgery: The CABG Patch Trial

Background: Whether prophylactic insertion of an implantable cardioverter defibrillator (ICD) improves the survival of high-risk patients undergoing coronary artery bypass graft surgery (CABG) is being assessed in the CABG Patch Trial. This report describes the surgical aspects of the study. Methods and Result: As of February 28, 1995, 847 patients (1.6% of 54 102 screened) were enrolled and eligible for randomization to CABG or CABG plus ICD. Intraoperatively, 56 were eliminated by postenrollment exclusions, 67 were judged too unstable for randomization, and 724 were randomized (80% of the goal of 900). The average preoperative ejection fraction was 0.27±0.06 (n = 724); left ventricular (LV) end-diastolic pressure averaged 22±12 mm Hg (n=548). Cardiopulmonary bypass (CPB) time averaged 108 minutes in control subjects, 126 minutes in the ICD group. After CPB, mechanical support was employed in 23% of patients and inotropic support in 73%; shock occurred in 8% and deep sternal wound infection in 1.3%. The surgical mortality was 6%; median length of stay was 8 days. Compared with randomized patients, patients whom surgeons judged too unstable to randomize were distinguished by statistically significant increases in mechanical support after CPB (51% versus 23%, P<.05) and postoperative shock (19% versus 8% P<.05). Also, surgical mortality was greater (9% versus 6%) but was not statistically significant. Conclusions: The initial phases of the CABG Patch Trial have been conducted with acceptable surgical mortality, morbidity, and length of stay. Surgical exclusion of some patterns from randomization has been corroborated by data indicating hemodynamic instability. This trial will provide information about the risks and outcome of CABG surgery in patients with impaired LV function.