Amiodarone in patients with previous drug-mediated torsade de pointes

Article Abstract:

Patients with abnormal heart rhythms can be treated with antiarrhythmic drug therapy. A potential complication of antiarrhythmic drug therapy, particularly with drugs that prolong the QT interval on an electrocardiogram (a recording of the electrical activity of the heart), is torsade de pointes. Torsade de pointes is an abnormally fast heart beat that appears on an electrocardiogram tracings with a changing pattern, first appearing negative and than positive. Amiodarone is an agent that can be used to treat abnormal heart beats, but it has unusual potency and is highly toxic. Since patients are at risk for torsade de pointes with antiarrhythmic therapy, there is some concern regarding the use of amiodarone, which theoretically can cause torsade de pointes itself, in patients who have previously experienced the condition. Electrocardiograms were studied in 12 patients who had experienced torsade de pointes with antiarrhythmic therapy, before and after amiodarone therapy. The QTc intervals were prolonged during the period of torsade de pointes, after initial amiodarone therapy and after three months of amiodarone therapy. After 16 months, torsade de pointes was absent in all 12 patients and no additional episodes were reported. Amiodarone does not tend to cause torsade de pointes and can be used safely and effectively to treat arrhythmias in patients with a previous episode of torsade de pointes. (Consumer Summary produced by Reliance Medical Information, Inc.)

Prevention, Torsade de pointes

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Amiodarone and torsade de pointes

Article Abstract:

Patients with abnormal heart rhythms can be treated with antiarrhythmic drug therapy. A potential complication, however, arising with drugs that prolong the QT interval on an electrocardiogram (a recording of the electrical activity of the heart) is torsade de pointes. Torsade de pointes is an abnormally fast heart beat that appears on an electrocardiogram tracings in a changing pattern, first looking negative and then positive. Amiodarone, an agent approved for use in treating abnormal heart beats, has unusual potency and is highly toxic. It is generally used as a last resort in the treatment of dangerously rapid heart rhythms. A study by Mattioni et al. in the Oct 1, 1989 issue of the Annals of Internal Medicine found that amiodarone did not cause torsade de pointes in patients who previously developed torsade de pointes due to other antiarrhythmic agents. Despite the tendency for amiodarone to prolong the QT interval, it can be used safely in selected patients. Although the mechanism is poorly understood, it is thought that amiodarone prevents torsade de pointes by blocking the transport of calcium and sodium into the heart muscle cells. (Consumer Summary produced by Reliance Medical Information, Inc.)

editorial

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Amiodarone: reevaluation of an old drug

Article Abstract:

Amiodarone appears to effectively treat several types of irregular heart rhythms, although it may cause side effects. This drug dilates blood vessels, slows the heart rate, and affects the electric activity of the heart. Because amiodarone is absorbed slowly and is stored in the fatty tissues of the body, it must be taken in high doses for a lengthy period to produce results. Eighty percent of patients taking amiodarone experience side effects, which are severe in 10% to 15% of cases. Amiodarone may adversely effect the heart, lungs, thyroid gland, gastrointestinal tract, skin, nervous system, and the eyes. The drug may prevent abnormal heart rhythms called atrial fibrillation or flutter in approximately 80% of patients. Amiodarone appears to reduce the rate of sudden death caused by a rapid, irregular heart rhythm in heart attack survivors and patients with disease that affects the heart structure and function.

Care and treatment, Cardiac patients

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