Results of the Companion Trial — Another Breakthrough in Electrophysiology

Recently, the Companion Trial was terminated via the Safety and Monitoring Board for that trial. This was a breakthrough trial in which patients with moderate to severe congestive heart failure (New York Heart Association class III and IV), left ventricular ejection fraction less than or equal to 35%, and a QRS duration of 120 milliseconds were randomized to either optimal medical therapy, optimal medical therapy plus biventricular pacing, or optimal medical therapy plus biventricular pacing with a back-up implantable defibrillator. The ratio of the randomization was 1:2:2, respectively. The study enrolled over 1,600 patients and found a significant reduction in combined all mortality and hospitalization in both the low and high voltage arms (pacing and defibrillator, respectively) of the study. Dr. Bristow, the principal investigator of the study, has indicated that the low-voltage arm had a trend towards reduction in mortality; however, the high-voltage arm did reach a significant reduction in mortality. What are the implications of this trial? Presently, the American College of Cardiology and American Heart Association has a Class IIA indication for implantation of implantable defibrillators in patients with prior myocardial infarction and an ejection fraction less than or equal to 30%. This trial will expand the indication for device implantation. In particular, it is possible that prophylactic implantation will be extended to patients with Class III and Class IV New York Heart Association congestive heart failure. This is an advance of the results for SCDHeFT (Sudden Cardiac Death in Heart Failure Trial), results who meet the Companion criteria. These patients will not receive the pacing-only device, but rather the combined pacing-defibrillator biventricular unit. That trial which consisted of mild to moderate congestive heart failure (NYHA Class II & III) patients who were randomized to placebo, amiodarone, or an implantable cardioverter-defibrillator already completed enrollment (approximately 2,500 patients) and in follow-up. We certainly look forward to the American College of Cardiology and The North American Society of Pacing and Electrophysiology Scientific sessions to disclose some, if not all, of the results of these trials.