Medical Device Daily Washington Editor

WASHINGTON — While the 2007 edition of Transcatheter Cardiovascular Therapeutics was focused largely on stents, cardiology specialties other than for interventionalists also found a home here this week, for instance, at a Wednesday session titled “Device-based management of worsening chronic heart failure.”

Though there was no attempt to form a consensus on the future of pacing equipment and pumping technology, it was difficult to miss the underlying message: The cardiovascular market will always be more than stents and other percutaneously-inserted devices.

But while most electrophysiologists (EPs) acknowledge that they need a better mechanism for risk stratification for patients with troubled tickers, agreement seems to be building to expand the use of pacing equipment to patients with less severe cases of congestive heart failure.

Arthur Moss, MD, of the University of Rochester Medical Center (Rochester, New York) discussed the use of implantable cardioverter defibrillators (ICDs) in patients with heart failure and left ventricular dysfunction. He said that an analysis of the data derived from seven studies looking at pacing equipment — including MADIT, MADIT II, CABG-Patch and others — demonstrated a clear benefit with the prophylactic use of implantable ICDs in prevention of sudden cardiac death.

“The overall result of these shows a hazard ratio” that is equal to “a 30% reduction in all-cause mortality,” Moss said. And while he said these patients “lived longer, they tended to die not from sudden death, but from heart failure.”

He acknowledged that some sort of risk rubric is needed to determine the best candidates for the therapy because fewer than half patients implanted in these studies end up receiving a shock. (And other estimates have put the numbers of those receiving a life-saving shock at less than 10% in real-life circumstances.)

In MADIT II, only 36% of the patients had any firings of their ICDs.

“We will never get 100% firing,” he said, no matter how robust a risk stratification mechanism is, he said, but expressing the opinion that an effective risk analysis should be able to increase accuracy to 70%.

ICDs “saves lives in appropriately selected patients,” Moss said.

As others before him have noted, ICDs change the course of heart disease. As Moss put it, an ICD “converts sudden cardiac death risk ...into a later heart failure event.” Patients who received ICDs and survived electrophysiological events “almost always [died of] heart failure.”

Moss said that the interval between index infarct and the outcome of ICD implantation ran anywhere from 17 to 121 months and that, in total, the seven studies demonstrated “very little, if an, benefit” in the first year. The benefit increases over time, though.

Bill Abraham, MD, the director of cardiovascular medicine at Ohio State University Medical Center (Columbus), briefly discussed cardiac resynchronization therapy (CRT), typically indicated in a case of heart failure, which consists of pacing for both ventricles, and he reviewed the results of studies conducted about this approach to heart failure.

“The pace at which patients have been enrolled and studied is relatively brisk,” Abraham said, totaling about 4,000 to date. “By and large, NYHA class III or AHA class IV patients ...have comprised the study populations.”

“Virtually all the usual endpoints ...have been evaluated” for functional and physiological outcomes, he said, with most primary endpoints being for function. But the Companion and Care HF were powered for morbidity and mortality.

The Companion study randomized roughly 1,500 patients into one of three arms: pharmacological therapy, cardiac resynchronization alone (RCT), and cardiac resynchronization combined with defibrillation (CRT-D).

The device groups both fared better than the drug group for time to death, by an almost identical margin, but the CRT-D combination provided a greater margin of improvement on the return-to-hospital outcome than pacing alone.

“Does CRT make heart failure patients feel better? The answer is yes,” Abraham said, citing the Miracle, Mustic SR and Contak studies, all demonstrating that “CRT compared to the control arms consistently improves quality of life and functional benefit,” consistently across studies.

Even exercise capacity showed improvement.

Abraham said that “three of four [studies] demonstrated marked improvement” of an additional 30 meters in the six-minute hall-walk test, on average. Peak serum oxygen saturation also improved.

As for whether the benefit in heart failure is sustained in biventricular pacing, Abraham said that the Miracle study says it is, showing that “patients with CRT devices for seven, eight or nine years now” continue to benefit by CRT. He added that CRT reduces cardiac enlargement in “a consistent finding across trials.”

Does CRT reduce morbidity and mortality in chronic heart failure?

Miracle says yes, according to Abraham, but he noted that Miracle cannot answer this question definitely because it was not designed to evaluate this endpoint. But, “there was a trend toward a 27% drop in all-cause mortality.”

Care-HF exhibited “a 36% reduction in all-cause mortality.”

Despite the still-present need for a more exhaustive risk stratification paradigm for the more severe cases of New York Heart Association Class III and IV, Abraham hinted at the possibility that NYHA Class I and II patients are seen as candidates for CRT.

The NYHA classification system for Class I patients describes them as those “with no limitation of activities” and “no symptoms from ordinary activities.” Class II patients are those “with slight, mild limitation of activity” who are “comfortable with rest or with mild exertion.

“At the top of the list of expanded indications is to less severe patients,” he said, including those who are mildly symptomatic or asymptomatic.

The Miracle ICD II trial indicates that even these patients will benefit from CRT by facilitating cardiac remodeling, Abraham said.