Monday, February 20, 2006

New drug reduces abnormal heart rhythms in patients with implanted cardioverter defibrillators

New drug reduces abnormal heart rhythms in patients with implanted cardioverter defibrillators: "New drug reduces abnormal heart rhythms in patients with implanted cardioverter defibrillators

This is featured simultaneously in a news conference at Scientific Sessions 2004 and published in the rapid access issue of Circulation: Journal of the American Heart Association (7:30 a.m. CST, Monday, Nov. 8, 2004).

NEW ORLEANS, Nov. 8 – A new drug reduced the recurrence of abnormal heart rhythms in patients with a defibrillator implanted in their heart, researchers reported today in a late-breaking clinical trial session at the American Heart Association’s Scientific Sessions 2004.

Results were simultaneously published in Circulation: Journal of the American Heart Association.

An implantable cardioverter defibrillator (ICD) is a device that treats life-threatening abnormal heart rhythms by delivering an electrical shock to the heart. Defibrillators can treat the abnormal rhythms when they happen, but many patients need other treatment to prevent symptomatic arrhythmias and to reduce the number of device therapies, explained Paul Dorian, M.D., M.Sc., director of the arrhythmia service, St. Michael’s Hospital, Toronto and professor of medicine, University of Toronto, Toronto, Canada; and chair of the SHock Inhibition Evaluation with AzimiLiDe (SHIELD) steering committee.

ICDs can deliver a shock to restore a normal rhythm or provide anti-tachycardia pacing (ATP), a series of pacing pulses to steady the rhythm. The machine records each patient’s arrhythmic episodes, and physicians can download that data by placing a probe on the patient’s skin.

The investigational drug, azimilide dihydrocholoride, blocks potassium channel currents in the heart known as IKS and IKR that can cause abnormal heart rhythms. The drug is known as a class III anti-arrhythmic agent.

In this study, 633 ICD recipients from 121 sites in nine countries were randomized to one of three groups: one 75 milligram (mg) daily dose of the azimilide dihydrocholoride, one 125 mg daily dose of the drug, or a placebo. Participants included patients with newly implanted ICDs who had experienced a life-threatening arrhythmia during the 42 days prior to implantation and patients who had their ICDs for more than 30 days and had a documented episode of arrhythmia in the 180 days before receiving the device.

The researchers found that azimilide dihydrocholoride reduced the total number of all-cause shocks plus the number of times ATP was used to steady ventricular tachycardia (VT). A ventricular tachyarrhythmia is a condition in which the defibrillator correctly treats the arrhythmia but the patient can experience recurrences with symptoms that may include shortness of breath, chest pain, dizziness or fainting. Relative risk reductions were 57 percent with the 75 mg dose and 47 percent with the 125 mg dose (relative to those taking a placebo).

In addition, the incidence of all appropriate ICD therapies (shocks or pacing-terminated VT) was reduced 48 percent among patients on 75 mg of azimilide dihydrocholoride, and 62 percent in patients taking 125 mg. Five patients in the test group and one in the placebo group developed torsade de pointes, a rhythm disturbance. All were successfully treated with the ICD. One patient in the 75 mg group developed severe but reversible neutropenia, a diminished number of neutrophils (a type of white blood cells) in the blood.

Co-authors are: Martin Borggrefe, M.D.; Hussein R. Al-Khalidi, Ph.D.; Stefan H. Hohnloser, M.D.; Jose M. Brum, M.D.; Daljit S. Tatla, Ph.D.; Johannese Brachmann, M.D.; Robert J. Myerburg, M.D.; David S. Cannon, M.D.; Michael van der Laan, M.d.; Michael J. Holroyde, Ph.D.; Igor Singer, M.D.; Craig M. Pratt, M.D. Disclosure information is included in the journal article.

Statements and conclusions of study authors that are published in the American Heart Association scientific journals are solely those of the study authors and do not necessarily reflect association policy or position. The American Heart Association makes no representation or warranty as to their accuracy or reliability.


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