New hope for heart attack survivors: recent data from a landmark trial show that implantable cardioverter defibrillators help prolong the lives of people who have had heart attacks.
The lifesaving study that Lepley refers to is the MultiCenter Automatic Defibrillator Implantation Trial (MADIT II), which the 81-year-old Minnesota native entered in May 1999. In the study, Dr. Arthur J. Moss of the University of Rochester Medical Center and colleagues were investigating whether ICDs could improve survival when compared to drug therapy alone in heart attack survivors with moderate impairment of the left ventricle--a profile that fit Joe Lepley to a tee. Findings from the MADIT II trial were so convincing that an independent review panel decided that the device's effectiveness no longer needed to be proven because it had clearly demonstrated the lifesaving benefits of ICDs.
Without the device, Lepley would almost certainly have died of sudden cardiac death, which claims the lives of 220,000 Americans annually--many of those deaths resulting from rhythm disturbances.
Under current FDA guidelines, about 300,000 patients are eligible each year to receive an ICD in the United States. But based on the new findings, this group could be significantly enlarged.
"With the new indications for the device, the number of patients who are eligible to receive it will be doubled," said Dr. David S. Cannom of Good Samaritan Hospital in Los Angeles and a member of the trial's Steering Committee. "The device works--it's incredibly effective at defibrillating the heart."
The Post interviewed Dr. Arthur Moss, lead investigator of the MADIT II trail, to learn more about the study and its potential in saving the lives of high-risk heart patients, like Joe Lepley and Vice President Dick Cheney.
Q: Could you share recent findings from the four-year MADIT II trial, published in the New England Journal of Medicine and reported on at the American College of Cardiology's annual scientific meeting?
A: The MADIT II trial is a study of implantable cardiodefibrillators (ICDs)--devices like the one implanted in Vice President Cheney. We studied a large group of 1,232 patients who had a prior heart attack and reduced pumping function of the heart that is measured by the ejection fraction--the fraction of blood pumped out of the heart with each heartbeat. Patients in the trial had an ejection fraction of less than 30 percent--about half of the ejection fraction of the normal heart, which is about 60 percent. In the trial, patients were randomized to receive the defibrillator or not receive it, and continue treatment with optimal medication.
The net result of the trial is that we saw a 31 percent reduction in total mortality in the patients treated with the defibrillator versus patients who did not receive the defibrillator. The data safety monitoring board overseeing the trial recommended stopping the trial, because the defibrillator proved so effective in saving lives.
This improvement in survival and reduction of mortality with the defibrillator is on top of optimal therapy with existing medications, such as beta blockers, lipid-lowering drugs, and ACE inhibitors. People with these conditions are usually on medication, and we made sure that the patients in the trial were receiving optimal medication. This finding represents a very meaningful addition to our therapeutic strategy.
As a team, we feel that this is a landmark step forward in therapy, because there have not been any drugs that were effective in preventing these dangerous, life-threatening heart rhythm disorders. I think that this broadens the therapy that can be rendered to patients.
Q: Is a 31 percent reduction in total mortality a significant finding?
A: A finding of 31 percent is larger than what is found in most standard trials and is pretty unusual and dramatic, suggesting a landmark finding. Currently, the standard treatment for heart attack patients is to treat them with beta blockers, based on findings from a 1983 study that associated beta blockers with a 27 percent reduction in mortality.
The second very large development in therapy for heart attack patients came from the Survival and Ventricular Enlargement (SAVE) trial. Researchers in the study used the drug captopril--an ACE inhibitor--which was associated with a 19 to 20 percent reduction in mortality.
The MADIT II study enrolled subjects from 76 centers--71 in the United States and 5 in Europe--so it was a very representative population of the patients at risk.
Q: For what conditions is the ICD currently indicated?
A: Vice President Cheney's indication was based upon our first MADIT trial, published in 1996 in New England Journal of Medicine, which dealt with selecting patients who had the types of dangerous heart rhythms like those uncovered with the vice president. I was consulted on therapy recommendations for the vice president.
Q: How many patients are currently implanted with a defibrillator in the United States?
A: At the present time, about 80,000.
Q: Does your study suggest that ICDs could be beneficial as a prophylactic intervention in a larger group of patients?
A: That was the basis of this trial. To get into the trial, patients did not have to manifest dangerous existing rhythm disorders, like those we observed in the earlier trial and like those of Vice President Cheney. The people in this trial had enough scar tissue in their hearts from prior heart attacks that we felt they were at risk for developing heart rhythm disorders, and that the defibrillator would save lives, which it did.
Q: How many people could potentially become eligible for an ICD based on the findings of your study?
A: Two million is the best estimate, based upon panel discussions from the National Heart, Lung, and Blood Institute. The best estimate was around three million, and we took just 80 percent of that to be conservative. So the population estimated to be at risk could be two million or four million.
Q: Is a prior heart attack the only precondition that would make patients eligible for an ICD?
A: In this study, our investigation focused on patients who had had several heart attacks, very similar to the types of heart attacks that Vice President Cheney experienced, although he qualified for an ICD because he had manifest heart rhythm problems.
Patients whom we enrolled in the trial had compromised heart function from scarring, but did not have manifest heart rhythm problems. This intervention was referred to as prophylactic therapy.
Other researchers are currently investigating other heart conditions--such as cardiomyopathy usually due to scarring from a viral infection.
Q: Does the therapy offer renewed hope to high-risk patients with heart failure?
A: Absolutely. The ICD prolongs life. A 31 percent reduction in mortality is quite considerable. Certainly, it offers hope to high-risk heart patients. The implantable defibrillator saves lives. But there are other causes of death from heart disease. Heart rhythm disorders make up about 40 percent of the risk for mortality. The other 60 percent are a result of further reduction in the pumping function of the heart. When you start combining this therapy [ICD] that prevents sudden death with medications to prevent the progression of the coronary disease such as lipid-lowering agents and drugs to improve the mechanical function of the heart, it gives quite a significant increase in life expectancy.
Q: Is this therapy expensive?
A: Let me put the cost issue in perspective. The fact is that if you are dealing with a small population of patients with high technology, it is expensive. Certainly, as you increase the number of patients, market forces will drive cost down.
For example, take the digital camera. Two years ago, a digital camera cost about $2,000. Today, you can get a very good digital camera for $200. There hasn't been a phenomenal breakthrough in technology, but because of the picture quality, a larger number of individuals use digital cameras. Market forces drove the price down.
Right now the cost of the implantable cardiodefibrillator is about $20,000. I think that market forces might well drive this down to the cost of a pacemaker, which is about $2,000. The first job is to make sure that the device works, then market forces will take care of price. Producing a dozen automobiles is expensive, but if a large number of people buy autos, the price comes down.
Q: Wasn't the same issue of cost a point of discussion when portable AEDs were first introduced?
A: The automatic external defibrillator used to cost $15,000 to $18,000. Now, you can get a very satisfactory AED for $2,000 to $3,000.
This is my view. I am not involved in the economics. I have no stock in any company and am not trying to propagate it. I am saying that we now have effective therapy to save lives, and market forces will be operative. I don't have any question about that.
Q: Many people are going to be interested in this therapy. What advice can you offer them? How do they go about investigating this on their own?
A: To get into the MADIT II trial, patients had to be receiving standard-quality medications--beta blockers, ACE inhibitors, and lipid-lowering drugs--and had to have a history of one or more documented heart attacks. For the patients who have had prior heart attacks, certainly their physicians are aware of this published study. For the people who qualify, one should provide optimal therapy. I think that there will be an increasing number of patients who are identified. Some will call their doctor today or tomorrow. Some will wait until their next appointment. As with any new effective therapy, it is going to be used.
Q: Will you be following up with another study?
A: We have finished this study and are now analyzing this rich database. A MADIT III trial is under discussion, but centers have not been selected.
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|Publication:||Saturday Evening Post|
|Date:||Jul 1, 2002|
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