CHICAGO – For the first time, cardiac resynchronization therapy has been shown to offer a survival benefit beyond that provided by an implantable cardioverter defibrillator in patients with mild heart failure, a study has shown.
The addition of cardiac resynchronization therapy (CRT) to an implantable cardioverter defibrillator (ICD) and optimal medical therapy significantly reduced the rates of death and heart failure hospitalization from 40% with an ICD alone to 33% in the multicenter Resynchronization/Defibrillation for Ambulatory Heart Failure Trial (RAFT).
Anthony Tang
The relative risk of death was reduced by 25% among patients who received CRT plus ICD, resulting in an absolute mortality reduction of 6% at 5 years, Dr. Anthony Tang reported at the annual scientific sessions of the American Heart Association. Fourteen patients would need to be treated with CRT plus ICD for 5 years to prevent one death.
Significantly fewer CRT-ICD patients were hospitalized for heart failure (19.5%, or 174/894) than ICD-only patients (26%, or 236/904). This meant that 11 patients would need to be treated with CRT plus ICD for 5 years to prevent one heart failure hospitalization, said Dr. Tang, professor of medicine at the University of British Columbia, Vancouver.
RAFT enrolled 1,798 patients (mean age, 66 years), who had New York Heart Association class II or III heart failure, a left ventricular ejection fraction (LVEF) of 30% or less, and a wide QRS duration of at least 120 milliseconds or a paced QRS duration of at least 200 milliseconds. Of note, 80% of patients were NYHA class II because during the trial the protocol was changed to include only class II patients.
CRT with or without an ICD is currently indicated only for the treatment of patients with NYHA functional class III or ambulatory class IV heart failure.
The data are likely to change clinical practice, said invited discussant Dr. Clyde W. Yancy, medical director of Baylor Heart and Vascular Institute at Baylor University Medical Center in Dallas and immediate past president of the AHA.
He observed that a suite of randomized trials including COMPANION, CARE-HF, MADIT-CRT, REVERSE, and now RAFT demonstrate compellingly that CRT is effective in heart failure.
Clyde W. Yancy
"The benefit can now be extended to patients that have mild heart failure," he said.
In the pivotal Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy (MADIT-CRT), however, the use of CRT-ICD therapy decreased the risk of heart failure events, but not the risk of death among NYHA class I or II patients with an ejection fraction of 30% or less and a QRS duration of 130 milliseconds or more (N. Engl. J. Med. 2009; 361:1329-38).
Dr. Yancy observed that CRT plus ICD is used in only about one-third of heart failure patients and suggested that its limited uptake is due to persistent equipoise, postprocedural risks that are not insignificant, an early failure rate of about 5% and a late failure rate of up to 25%, imprecise markers of clinical response, and current guidelines.
"We should no longer let equipoise enter into our thought process about the benefits of ICD-CRT in heart failure," he said.
The improved outcomes, however, did come at the cost of increased adverse events. Within 30 days of device implantation, significantly more CRT-ICD patients than ICD-alone patients had lead dislodgement (61 vs. 20 patients) and coronary sinus dissection (11 vs. 0), Dr. Tang reported. The CRT-ICD and ICD-alone groups had similar rates of hemothorax or pneumothorax (11 vs. 8 patients), pocket hematoma (14 vs. 11), pocket infection (21 vs. 16), tamponade (1 vs. 2), and device pocket revision (4 vs. 1).
An analysis by NYHA class showed that the majority of positive results held true, Dr. Tang said. The primary composite end point was significantly improved in both NYHA class II and III patients, while death from any cause was significantly improved among class II, but not class III patients.
Also, a post-hoc subgroup analysis of the primary end point suggests that patients with an intrinsic QRS duration of more than 150 milliseconds derive more benefit from CRT-ICD therapy, as do those with left bundle branch block, although the latter finding was weaker, Dr. Tang said. There was a trend for women to fare better with CRT plus ICD, but it was not significant.
Dr. Yancy said the observations raise intriguing considerations, but are prone to the pitfalls of post-hoc analyses, and do not indicate how to refine the rate of success and minimize morbidity.
During a panel discussion of RAFT, session moderator Dr. Marc Alan Pfeffer, the Victor J. Dzau Professor of Medicine at Brigham and Women’s Hospital in Boston, said further trials in this population are unlikely and asked whether current data are enough to suggest the use of CRT plus ICD in patients with left bundle branch block.