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 cardiovert er defibrillator (ICD) improves the survival of high-risk patients und ergoing 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 Results 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 pos tenrollment exclusions, 67 were judged too unstable for randomization, and 724 were randomized (80% of the goal of 900). The average preoper ative ejection fraction was 0.27+/-0.06 (n=724); left ventricular (LV) end-diastolic pressure averaged 22+/-12 mm Hg (n=548). Cardiopulmonar y bypass (CPB) time averaged 108 minutes in control subjects, 126 minu tes in the ICD group. After CPB, mechanical support was employed in 23 % of patients and inotropic support in 73%; shock occurred in 8% and d eep sternal wound infection in 1.3%. The surgical mortality was 6%; me dian length of stay was 8 days. Compared with randomized patients, pat ients whom surgeons judged too unstable to randomize were distinguishe d by statistically significant increases in mechanical support after C PB (51% versus 23%, P<.05) and postoperative shock (19% versus 8%, P<. 05). Also, surgical mortality was greater (9% versus 6%) but was not s tatistically significant. Conclusions The initial phases of the CABG P atch Trial have been conducted with acceptable surgical mortality, mor bidity, and length of stay. Surgical exclusion of some patients from r andomization has been corroborated by data indicating hemodynamic inst ability. This trial will provide information about the risks and outco me of CABG surgery in patients with impaired LV function.