Amiodarone: Lifesaver for shock-resistant patients
Study shows EMS use beneficial
Amiodarone could soon be approved for use in resuscitating en route heart attack patients who don't respond to defibrillation. The antiarrhythmia medication is approved for emergency infusion in a hospital or clinic setting for patients with recurrent life-threatening ventricular tachycardia/ventricular fibrillation refractory to or intolerant of other antiarrhythmic agents. Its use outside that setting as a last-resort field medication is not yet approved, however.
Cordarone IV, manufactured by Radnor, PA-based Wyeth-Ayerst, has been shown to keep patients alive while en route the hospital. Whether it becomes a part of your facility's EMS armamentarium may be influenced by that factor but also by its cost: $60 per amp, so a resuscitative dose is $120. "That's not a lot to save someone's life," says Les Wooldridge, RN, education coordinator of the resuscitation program at Vanderbilt University Medical Center in Nashville, TN, "but we have no clear documentation as yet that it can." Lidocaine, the standard treatment, costs about $5 a dose.
Amiodarone was the subject of a clinical trial dubbed ARREST (Amiodarone in the Out-of-Hospital Resuscitation of Refractory Sustained Ventricular Tachyarrhythmias) reported at the American College of Cardiology meeting in Atlanta, in late March. The trial compared the effectiveness of the antiarrhythmic with all other standard treatments in patients who suffer out-of-hospital cardiac arrest and are not responding to shock treatment. University of Washington researchers showed that resuscitation to a stable heart rhythm was improved by 26% in patients treated with IV amiodarone, compared to those who received all other standard treatments for cardiac arrest. Among people in whom defibrillation shocks alone could only temporarily maintain a stable heartbeat, amiodarone improved by 56% their chances of being admitted alive to the hospital.
"The majority [of heart attack victims] do not respond to defibrillation treatments alone, and more than two-thirds die before reaching the hospital," said Peter Kudenchuk, MD, lead investigator and associate professor of medicine and director of arrhythmia services at University of Washington Medical Center in Seattle. Amiodarone helped "resuscitate individuals who suffered a cardiac arrest outside the hospital and whose hearts had not resumed beating after three or more cardiac defibrillation shock treatments."
The drug was administered to 500 people in Seattle and King County, WA, who suffered cardiac arrest due to refractory ventricular fibrillation between November 1994 and February 1997. More than three-quarters of the patients were men ranging in age from 20 to 94 years. Thirty-nine percent survived until admission, compared to the 26% receiving standard treatment, lidocaine.
Amiodarone not without risks
No other medication has been shown to have such effectiveness in treating shock-resistant cardiac arrest, said Kudenchuk. The main endpoint for the ARREST trial was being admitted alive to a hospital; the trial was not sufficiently large to evaluate the effect of treatment on the likelihood of being discharged from the hospital alive. Although a slight improvement in survival to hospital discharge was observed, that was not felt to be conclusive. "Amiodarone is not a simple drug," says Wooldridge. "It has an extremely long half-life. Even years later, patients have traces in their systems."
Amiodarone's use is not without risks. A meta-analysis done at the University of Wisconsin School of Medicine in Madison showed that "exposure . . . at relatively low maintenance doses for a minimal duration of 12 months resulted in odds similar to those of placebo for hepatic and gastrointestinal adverse effects, but in significantly higher odds than those of placebo for experiencing thyroid, neurologic, skin, ocular, and bradycardiac adverse effects."1 Patients randomized to the drug were twice as likely to experience pulmonary toxicity in dose-related phenomena.
Kimberly Bell, RN, CCRN, nurse clinician for the coronary care unit and coronary progressive care unit at St. Francis Hospital & Health Centers in Beech Grove, IN, says that her facility follows the American Heart Association guideline and uses only those rescue drugs included in that algorithm. "Amiodarone is not a part of that," she says.
Reference
1. Vorperian VR, Havighurst TC, Miller S, et al. Adverse effects of low dose amiodarone: A meta-analysis. J Am Coll Cardiol 1997;30:791-798.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content