FDA Approves New Indications for CRT-D Devices Based on MADIT-CRT

Reed Miller

September 17, 2010

September 17, 2010 (Natick, Massachusetts) — The FDA is expanding the approved indications for three Boston Scientific cardiac resynchronization defibrillators (CRT-D) to include patients with milder heart failure and left bundle branch block [1].

The September 16 approval follows the advice of the agency's Circulatory System Devices Panel, which voted in favor of the indication expansion at its March 19 meeting, covered by heartwire . The latest approval expands the indication to also include patients with left-bundle branch block (LBBB) and NYHA Class 2 or ischemic Class I heart failure with an LVEF < 30% and a QRS duration > 130 ms. The new LVEF and electrocardiographic criteria are more restrictive than the current FDA-approved indication for CRT-D, which covers patients with NYHA class 3-4 heart failure, LVEF <35%, and a QRS >120 ms.

Boston Scientific's products are now the only CRT-D devices approved for the expanded indication. The company requested the new indication based on the results of the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT), which showed patients with CRT-D devices had a one-third lower risk of death or heart-failure events over 2.5 years than patients with regular ICDs. There was no significant difference in death, but a 41% difference in heart-failure events.

LBBB was a marker of increased benefit with CRT-D in a subgroup analysis and its inclusion in the indication was one of the few areas of disagreement at the March advisory panel meeting. In patients with left bundle branch block--70% of the MADIT-CRT population--CRT-D reduced the risk of death and heart failure events 57% compared to ICD alone.

"The rate of complications was considered to be acceptable by the FDA for this device; however, physicians should adequately inform patients about potential complications," the agency states in a press release.

As a condition of approval, Boston Scientific has agreed to conduct two post-approval studies: a study of data from the National Cardiovascular Data Registry to evaluate long-term mortality benefits and complication risks of CRT-D in patients with LBBB, and a study following the original MADIT-CRT patients for five years to assess the long-term mortality benefits of CRT-D versus ICD-alone.

At their recent congress in Stockholm, the European Society of Cardiology announced new guidelines for CRT-D therapy, which added patients with NYHA class 2 heart failure to the traditional NYHA class 3-4 indication, but do not include NYHA class 1 heart failure or have a restriction based on left bundle-branch block.