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Antiarrhythmic Drugs Distant Second to Implantable Cardioverter Defibrillators.

SNOWMASS, COLO. -- Antiarrhythmic agents no longer have any role as primary therapy in patients with low ejection fraction and clinical or inducible ventricular tachycardia, Dr. Roger A. Winkle declared at a conference sponsored by the American College of Cardiology.

The cumulative evidence from multiple randomized clinical trials is overwhelming: An implantable cardioverter defibrillator (ICD) is the best treatment for such patients.

"For patients like this, we should be putting ICDs in the drinking water," quipped Dr. Winkle, director of the cardiac surveillance unit and electrophysiology laboratory at Sequoia Hospital in Redwood City, Calif.

The status of ICDs for prevention of arrhythmic death is comparable to that of statins for the prevention of coronary events in at-risk patients. The incontestable merits of both forms of therapy are backed by compelling clinical trial data. Yet both therapies are clearly underused in practice, he said.

A large patient population that would benefit from much wider use of ICDs consists of individuals with coronary artery disease, a left ventricular ejection fraction of 40% or less, and nonsustained asymptomatic ventricular tachycardia (VT).

"Based on the results of both the Antiarrhythmics Versus Implantable Defibrillators [AVID] Registry and MUSTT [the Multicenter Unsustained Tachycardia Trial], [ldots] we should be very actively searching in our practices for these patients. There are just a tremendous number of such patients who should have devices put in who really aren't getting the benefit of this treatment," he said.

He recommended searching for asymptomatic nonsustained VT by performing a treadmill stress test or Holter monitoring in coronary patients 3-4 weeks after an MI or acute intervention. The same tests are useful in identifying good candidates for ICD therapy among patients known to have a low ejection fraction.

In the recently published MUSTT, which involved patients with coronary disease, a low ejection fraction, and asymptomatic nonsustained VT, all of the survival benefit was confined to patients who underwent electro-physiologically guided therapy with ICDs. Patients who received electrophysiologically guided antiarrhythmic drug therapy actually had slightly worse survival than control subjects given neither ICD nor drugs (N. Engl. J. Med. 341[25]:1882-90, 1999).

Another group in which new evidence suggests that ICDs may be indicated consists of patients with a low ejection fraction who have experienced cardiac arrest for what was thought to be a transient and correctable cause, such as hypokalemia or digitalis toxicity.

AVID Registry data showed that the 3-year mortality of such patients was surprisingly high, quite similar to that of groups that are universally recognized as being at high risk, such as patients who have ventricular fibrillation cardiac arrest or syncopal VT (Circulation 99[13]:1692-99, 1999).

"This really makes a strong point: You should not stand there for hours worrying that the serum potassium was 3.0 or 3.1. You probably should just go ahead and put a device in," Dr. Winkle said.

Arrhythmologists eagerly await results from two ongoing randomized trials looking at the mortality effects of ICDs versus antiarrhythmic drugs in patients with poor left ventricular function but no sustained or inducible VT to serve as markers for increased arrhythmic death risk. The Sudden Cardiac Death in Heart Failure Trial involves patients with class II-III heart failure. The Second Multicenter Automatic Defibrillator Implantation Trial focuses on patients with ischemic cardiomyopathies.
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Comment:Antiarrhythmic Drugs Distant Second to Implantable Cardioverter Defibrillators.
Publication:Family Practice News
Article Type:Statistical Data Included
Geographic Code:1USA
Date:Apr 1, 2000
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