May 19, 2004 -- For most people with severe heart failure and irregular heartbeats, a combination of a high-tech pacemaker and implantable defibrillator may provide the best protection against death, according to new research.
Researchers say the results of the two major studies published in this week's New England Journal of Medicine may lead to wider use of the devices in people with severe heart failure -- a condition in which the heart cannot pump enough blood to meet the body's needs.
The pacemakers studied not only help the heart keep up when its natural beat is too slow like traditional pacemakers, but they also make the heart pump more efficiently. Meanwhile, an implantable cardioverter defibrillator (ICD) delivers an electrical shock to prevent potentially dangerous heart rhythm abnormalities.
In the first study, researchers compared the effectiveness of the advanced pacemaker and implantable defibrillator vs. drug therapy in preventing hospitalization or death in people with advanced heart failure. They found the devices offered the greatest benefits, and use of both reduced the risk of death in patients with severe heart failure by 36%.
The second study showed that implanting a defibrillator in people with heart failure not caused by coronary artery disease or hardening of the arteries significantly reduced their risk of sudden death. People with this type of heart failure often die suddenly due to an irregular heartbeat.
Devices Beat Drug Therapy Along for Heart Failure
The first study looked at whether adding a pacemaker or ICD to traditional drug therapy for heart failure provided additional health benefits in reducing the risk of death or hospitalization for more than 1,500 people with advanced heart failure.
The heart failure patients were randomly assigned to receive drug therapy (including diuretics, ACE inhibitors, beta-blockers, and others), alone or in combination with either a pacemaker or a pacemaker-defibrillator combination.
Researchers found that compared with drug therapy alone, use of a pacemaker reduced the risk of death or hospitalization from any cause by 19%, and use of both devices reduced the risk by 20%.
Overall, the study showed that use of a pacemaker reduced the risk of death from any cause by 24%, and the combination pacemaker-defibrillator reduced the risk by 36%.
ICDs Reduce Sudden Death Risks
In the second study, researchers looked at whether an implantable defibrillator was useful as a primary prevention tool in people with a form of heart failure known as nonischemic cardiomyopathy. This type of heart failure is not caused by coronary artery disease or hardening of the arteries and commonly causes sudden death due to an irregular heartbeat.
Researchers say treatment with drugs such as ACE inhibitors and beta-blockers has been shown to prolong the lives of people with this type of heart failure, but these people are still at risk for sudden death due to heartbeat irregularities.
ICDs have been used as a preventive measure to protect against sudden death in people who have already experienced cardiac arrest or rapid and irregular heartbeats, but researchers say that this was the first large-scale study to look at whether defibrillators might also provide benefits in preventing sudden death in people with this type of heart failure.
In the study, researchers randomly assigned 458 people with this type of heart failure to receive standard drug therapy or drug therapy plus an ICD. The participants were then followed for nearly two-and-a-half years.
During that time, 68 deaths occurred, but only 28 of them occurred in the ICD group compared with 40 in the standard therapy group. Seventeen of the deaths were sudden deaths caused by an irregular heartbeat: three in the ICD group and 14 in the drug therapy group.
Based on those results, researchers say it's too soon to recommend routine implantation of ICDs in all people with heart failure not related to coronary artery disease. But the apparent benefit of the devices in certain subgroups suggests that use of these devices should be considered on a case-by-case basis.
Valuable Information, but Proceed With Caution
In an editorial that accompanies the study, Joseph G. Rogers, MD, and Michael E. Cain, MD, of Washington University School of Medicine, say these studies add critical new information about the use of the new generation of advanced pacemakers and implantable defibrillators to prevent future complications.
They say that until now, trials evaluating this approach have been small and evaluated the quality of life, exercise performance, and other heart performance factors. This new data on their health benefits in reducing illness and death is needed as doctors begin to use these relatively expensive therapies in a larger group of patients.
In another commentary, Mark Hlatky, MD, of Stanford University School of Medicine, says that the release of this new data will likely put pressure on insurance providers, such as Medicare, to expand coverage for these devices. He says it is also "very likely that the rate of implantation will increase dramatically, propelled by the same forces that fueled the expansion of bypass surgery."
However, as with bypass surgery, Hlatky says the key question regarding preventive use of defibrillators is not just whether it "works" overall, "but how much the risks, benefits, and costs vary among the different subgroups of patients with heart disease."
The first study was supported by medical device manufacturer Guidant, and the second was funded by a grant from St. Jude Medical, which is a WebMD sponsor.