“The results of the present MADIT-CRT sub-study show for the first time that CRT is associated with a pronounced reduction in the risk of repeated HF episodes,” say the authors of the report in the August 9 issue of the Journal of the American College of Cardiology.
Dr. Ilan Goldenberg, at the University of Rochester Medical Center, New York, and colleagues point out that trials of cardiac resynchronization therapy (CRT) for heart failure have mainly assessed the combined endpoint of a first heart failure event or death, so the effect on subsequent occurrences has been unknown.
In the MADIT-CRT trial, 1820 patients were assigned to receive either a CRT-defibrillator device or an implantable cardioverter-defibrillator (ICD) if they had milder symptoms. A pre-specified sub-study (ie, the current study) assessed the benefit in preventing recurring heart failure events (HFEs).
“The diagnosis of an HFE, made by physicians aware of the implanted devices, required signs and symptoms consistent with congestive HF that was responsive to intravenous decongestive therapy on an outpatient basis or an augmented decongestive regimen with oral or parenteral medications during an in-hospital stay,” according to the report. “Adjudication of the endpoints was carried out by an independent HFE committee blinded to device implantation information.”
Compared with the ICD group, those receiving a CRT-defibrillator had a significant reduction in first heart failure events (hazard ratio 0.54) and in subsequent HFEs (HR 0.62), the team found on multivariate analysis. This benefit was confined almost entirely to patients with left bundle branch block at enrollment.
Furthermore, during 2 years of follow-up, mortality risk was significantly increased with a first HFE versus no HFE (HR 7.24) and even more with a second HFE (HR 18.7) – confirming “the prognostic implications of recurring HFEs in patients with left ventricular dysfunction.”
Dr. Goldenberg and colleagues conclude, “These findings should be incorporated in the risk assessment and management of patients who receive device therapy for the prevention of HF and sudden cardiac death and stress the importance of evaluating risk for recurrent events in clinical trials.”
An accompanying editorial calls the findings “a major extension of our knowledge” about the long-term effects of CRT. However, the author notes that the study does not address overall healthcare utilization.
“In contrast to insertion of an ICD without CRT capabilities, the addition of a left ventricular lead is associated with excess perioperative complications, such as dissection and perforation of the coronary sinus, phrenic nerve capture, and lead dislodgment,” points out Dr. Frieder Braunschweig, with Karolinska University Hospital in Stockholm, Sweden.. “These and other device-related problems commonly cause prolonged initial hospital stays, repeat hospital stays, and extra visits and can offset the gains in HF-specific endpoints.”
Reduction of the Risk of Recurring Heart Failure Events With Cardiac Resynchronization Therapy: MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy)
J Am Coll Cardiol 2011;58:729–737.