Preliminary results of Boston Scientific's MADIT-CRT study show a significant benefit for cardiac resynchronization therapy implants over conventional defibrillators for patients with mild heart failure; the data could support expanded labeling and increased market adoption for the premium-priced devices, industry watchers say.

Cardiac resynchronization therapy defibrillators (CRT-Ds) reduced death or heart failure interventions by 29% over traditional implantable cardioverter defibrillators in patients with mild heart failure - meeting the trial's primary endpoint and concluding the study June 22.

The results show that CRT-Ds "slow the progression of heart failure in asymptomatic and mildly symptomatic patients," the company reported the next day.

The 1,800-patient MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial-CRT) study, which began in December 2004, is the largest CRT-D randomized trial to date of high-risk, asymptomatic or mildly symptomatic patients with New York Heart Association (NYHA) Class I and II heart failure.

While the devices currently are indicated only for patients with advanced heart failure (NYHA Class III/IV), about 70% of heart failure patients have milder Class I/II heart failure, and manufacturers including Boston Scientific, Medtronic and St. Jude Medical are hoping that emerging data will help broaden the market to include milder cases.

"We are very encouraged by these initial positive results, and we are hopeful they will eventually lead to a wider population of heart failure patients being treated with CRT-D therapy," said Fred Colen, president of Boston Scientific Cardiac Rhythm Management. About 5.5 million Americans have some form of the disease.

Boston Scientific said it plans to publish the results of MADIT-CRT in their entirety later this year, after which it will file for expanded FDA labeling to treat Class I/II patients. Medtronic previously announced in May that it would seek an indication in mildly symptomatic patients, and St. Jude says it also plans to seek expanded CRT-D labeling.

Based on the interim data, MADIT-CRT has the potential to drive labeling expansion and a product mix shift from traditional implantable cardioverter defibrillators to the more expensive CRT-Ds, J.P. Morgan analyst Michael Weinstein suggests.

CRT-Ds sell at a price premium of $7,000-$8,000 over conventional defibrillators, analysts say.

"We view this event as the first meaningfully positive catalyst" for the $6.4 billion worldwide implantable defibrillator market since 2004, Weinstein continued.

Findings Could Add $600 Million To Market In 2012

A "mix shift" toward CRT-Ds from ICDs could add $258 million to the implantable defibrillator market by 2012, Weinstein said. If expanded labeling also is approved, the market could grow by $500 million-$600 million in 2012, he suggested.

While there currently is some off-label use of CRT-D devices in Class I/II patients, the MADIT-CRT results "should bode well for reimbursement and adoption in the less sick Class I/II population," echoed Morgan Stanley analyst David Lewis.

Boston Scientific's release of the initial MADIT-CRT data follows Medtronic's March update of results from its smaller, 610-patient REVERSE trial of CRT therapy in patients with mild heart failure.

While REVERSE did not meet its primary endpoint of a statistically significant difference in the percentage of patients whose heart failure status score worsened at one-year, data on 262 patients at two years did show that CRT treatment plus medical therapy reduced the risk of death and heart failure hospitalization by 62% compared to medical therapy alone.

CRT therapy works by pacing both sides of the heart to bring electrical functioning of the two ventricles into synchrony, while standard defibrillators deliver high-energy jolts when needed to stop fibrillation.

- Brooke McManus (b.mcmanus@elsevier.com)

MADIT-CRT Data Support Expanded Cardiac Resynchronization Market

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