HRS: Medical therapy & ICDs face off in cardiac death management

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SAN FRANCISCO—While a large amount of data have shown that medical therapy for heart failure (HF) may reduce sudden cardiac death (SCD), JoAnn Lindenfeld, MD, of the University of Colorado Health Sciences Center in Denver, said we are still not out of the woods yet in terms of finding the proper management strategies for SCD, during a May 5 presentation at the annual Heart Rhythm Society meeting.

“Do the benefits of medical therapy change as heart failure progresses?” Lindenfeld asked. “It is possible now that medical therapy has reached the point for the prevention of sudden cardiac death where defibrillators may not provide anywhere near the advantage that we once thought had.”

Lindenfeld noted that as HF progresses, deaths related to HF become more important and SCD becomes less important as a percentage of death. “The absolute number of patients who die of sudden cardiac death actually increases as HF progresses,” Lindenfeld offered. “The number of patients who die of heart failure progresses even more but still, sudden cardiac death is important even in end-stage heart failure.

During the study, the researchers at the Halifax Heart Failure Clinic in Halifax, Canada found that as the comorbidity index increases so does the risk of dying of progressive HF. “As the comorbidity index increased there was less tachyarrhythmia deaths and less benefit of devices [ICDs] to reduce sudden cardiac death,” Lindenfeld offered.

Can medical therapy manage SCD?
Across the board Lindenfeld said that beta-blockers have the most impact on reducing SCD. In fact, studies evaluating Class II through Class IV HF patients have documented an almost 30 percent risk reduction in SCD.

“There is quite a large benefit on total mortality and sudden cardiac death and post-MI,” she said.

However, Lindenfeld indicated that some of these beta-blocker trials were stopped prematurely and could have overestimated the risk reductions. Even with this possible overestimation, Lindenfeld said that there is still probably a 25 to 30 percent reduction in SCD with beta-blockers.

As for ACE inhibitors, Lindenfeld noted that data is less clear. While ACE inhibitors seemed to reduce total mortality significantly, there was no differences in SCD in Class IV HF patients (CONSENSUS trial). When summarizing all post-MI trials, Lindenfeld said that there is probably a 15 to 20 percent reduction in SCD. “There is probably a modest reduction with ACE inhibitors, but it’s nothing like the consistent, significant reduction we see with beta-blockers.”

Additionally, Lindenfeld said that aldosterone antagonists “are looking to look like beta-blockers in terms of their benefits to reduce both mortality and cardiac death.” Results of the EMPHASIS trial evaluating mild HF patients, showed a “highly significant reduction in SCD and total mortality.” Lindenfeld said that this was an estimated 20 to 25 percent reduction “not as much as beta-blockers but surely reproducible benefit.”

She also noted that early administration of  aldosterone antagonists may be critical to reducing total mortality and SCD. “Early administration of these can affect remodeling,” Lindenfeld said. And while ACE inhibitors and beta-blockers may help curb SCD, statins showed absolutely no benefit in reducing the risk of SCD like previously thought.

“Do the benefits of medical therapies change as the HF progresses?” asked Lindenfeld. “It doesn’t appear to change with beta-blockers or ACE inhibitors.”

Studies have now suggested that relative reduction in SCD is the same across the board. “The absolute number is greater as heart failure progresses but beta-blockers and aldosterone antagonists have benefit to reduce sudden cardiac death in mild to moderate to severe heart failure patients.

“Whether we are we at the point where medical therapy will replace ICDs is still unknown but we need to think about sudden cardiac death prevention,” Lindenfeld concluded.