The Coronary Artery Bypass Graft Patch Trial - CABG PATCH
The Coronary Artery Bypass Graft (CABG) Patch trial was designed to assess whether prophylactic insertion of an implantable cardioverter defibrillator (ICD) improves the survival of high-risk patients undergoing CABG surgery.
Prophylactic insertion of an ICD will reduce all-cause mortality in CABG surgery patients who are at high risk of late arrhythmic death.
Patients Screened: 54,102
Patients Enrolled: 724
NYHA Class: 2.5
Mean Follow Up: Not given
Mean Patient Age: 63.4 ± 9.3
Mean Ejection Fraction: <0.25% = 26.7
Clinical indication for elective CABG surgery, age <80 years, LVEF <0.36 (to increase overall risk), and abnormal SAECG (to increase risk of ventricular arrhythmias)
History of sustained ventricular tachycardia (VT); ventricular fibrillation (VF); or cardiac arrest with inducible VT (not associated with acute myocardial infarction); renal dysfunction (creatinine >3 mg/dl); insulin-dependent diabetes mellitus with significant vascular complications or history of poor control and recurrent infections; unipolar pacemakers; previous or concomitant aortic or mitral valve surgery; concomitant cerebrovascular surgery; emergency CABG surgery; thrombolysis within two days; concomitant arrhythmia surgery or LV aneurysmectomy; comorbidity associated with expected survival <2 years; home too far away to return for follow-up visits; inadequate time to obtain consent; enrolled in a competing trial before enrolling in this trial; physician, surgeon, or patient refusal; or unable to understand consent or comply with protocol, or both
Death of any cause
CABG and ICD insertion
Among randomized patients, the initial phases of the trial have acceptable mortality (overall surgical mortality = 5.9%), morbidity (cardiopulmonary bypass = 23%; shock = 8%; deep sternal wound infection = 1.3%), and length of stay (median = 8 days). During an average follow-up of 32 ± 16 months, there were 101 deaths in the defibrillator group (71 from cardiac causes) and 95 deaths in the control group (72 from cardiac causes). The hazard ratio for death from any cause was 1.07 (95% confidence interval 0.81-1.42, p=0.64).
The original design called for 800 patients to be randomized to ICD prophylaxis or to no therapy, and followed for two to 6.5 years (average, 40 months) to a common termination date. Because the ICD pulse generators used in this trial lasted about 42 months, the original design required ICD replacement in many patients.
In June 1994, an unanticipated subpoena from the Office of the Inspector General made it impossible to replace about half of the ICD generators, and threatened to shorten follow-up substantially. After reviewing many options for restoring power, the Data Safety and Monitoring Board recommended that the sample size be increased from 800 to 900 patients, and that almost all patients be followed for 42 months. This recommendation extended follow-up for two years beyond the original termination date planned for the trial.
The interim analysis found no evidence of improved survival among patients with coronary heart disease, a depressed left ventricular ejection fraction (LVEF), and an abnormal signal-averaged electrocardiogram (SAECG) in whom a defibrillator was implanted prophylactically at the time of elective CABG. Definitive comparisons of device and control groups will not be available until the completion of the trial.
1) Spotnitz HM, Herre JM, Baker LD Jr, Fitzgerald DM, Kron IL, Bigger JT Jr. Surgical aspects of a randomized trial of defibrillator implantation during coronary artery bypass surgery. The CABG Patch Trial. Circulation 1996;94:II248-53.
2) Curtis AB, Cannom DS, Bigger JT Jr, et al. Baseline characteristics of patients in the coronary artery bypass graft (CABG) Patch Trial. Am Heart J 1997;134:787-98.
3) Bigger JT Jr. Prophylactic use of implanted cardiac defibrillators in patients at high risk for ventricular arrhythmias after coronary-artery bypass graft surgery. Coronary Artery Bypass Graft (CABG) Patch Trial Investigators. N Engl J Med 1997;337:1569-75.
4) Bigger JT Jr, Parides MK, Rolnitzky LM, Meier P, Levin B, Egan DA. Changes in sample size and length of follow-up to maintain power in the coronary artery bypass graft (CABG) patch trial. Control Clin Trials 1998;19:1-14.
Keywords: Tachycardia, Ventricular, Ventricular Fibrillation, Coronary Disease, Stroke Volume, Wound Infection, Cardiopulmonary Bypass, Electrocardiography, Coronary Artery Bypass, Defibrillators, Implantable, Length of Stay
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