Authors
JT Bigger for the CABG Patch trial investigators
Title
Prophylactic use of implanted cardiac defibrillators in patients at high risk for ventricular arrhythmias after coronary-artery bypass graft surgery.
References
N Engl J Med 1997;337(22):1569-75.
Background
Patients with coronary heart disease, left ventricular dysfunction, and abnormalities on signal-averaged electrocardiograms have an increased risk sudden death
Purpose
The CABG Patch trial was designed to assess whether an ICD is associated with additional survival benefit in patients at high risk for sudden cardiac death. The trial investigators evaluated the effect on survival of the prophylactic implantation of cardioverter-defibrillators in such patients at the time of elective coronary-artery bypass surgery.
Design
  • Multicentre randomized controlled trial
  • Over the course of five years, 37 clinical centers (35 in US and 2 in Germany) screened all patients who were scheduled for elective coronary bypass surgery.
  • Patients were eligible for the trial if they were less than 80 years old, had a left ventricular ejection fraction of ≤35%, and had abnormalities on signal-averaged electrocardiograms.
  • Patients were randomized to ICD implantation at the time of CABG surgery or to CABG alone.
  • The primary end point of the study was overall mortality, and the two groups were compared in an intention-to-treat analysis.
Exclusion Criteria
Patients were excluded if they had a history of sustained ventricular tachycardia or fibrillation, diabetes mellitus with poor blood glucose control or recurrent infections, previous or concomitant aortic- or mitral-valve surgery, concomitant cerebrovascular surgery, a serum creatinine concentration greater than 3 mg per deciliter (265 mmol/liter), emergency coronary bypass surgery, a noncardiovascular condition with expected survival of less than two years, or an inability to attend follow-up visits.
Follow-Up
  • 32+/-16 months (mean +/- SD)
  • At 42 months, the cumulative rate of crossover to the control group was 10 percent, and the cumulative rate of crossover to the defibrillator group was less than 5 percent.
Treatment Regimen
Among 1422 eligible patients, enrolled 1055, and randomly assigned 900 to therapy with an implantable cardioverter-defibrillator (446 patients) or to the control group (454 patients).
Results

Primary Endpoints

  • 101 deaths in the defibrillator group (71 from cardiac causes) and 95 in the control group (72 from cardiac causes).
  • The hazard ratio for death from any cause was 1.07 (95 percent confidence interval, 0.81 to 1.42; P=0.64).

Secondary Outcomes

  • There was no statistically significant interaction between defibrillator therapy and any of 10 preselected base-line covariates.
  • Significantly more postoperative infections were reported in the defibrillator group (Table 3), and significantly more myocardial infarctions were reported during long-term follow-up in the control group.
Summary
  • There was evidence of improved survival among patients with coronary heart disease, a depressed left ventricular ejection fraction, and an abnormal signal-averaged electrocardiogram in whom a defibrillator was implanted prophylactically at the time of elective coronary bypass surgery.
  • These findings were essentially mirrored in other studies of ICD after acute myocardial infarction and reinforce the role of ICD therapy to be one for chronic LV dysfunction.