Amiodarone with implantable cardioverter

Strickberger SA, Hummel JD, Bartlett TG, et al. Amiodarone versus implantable cardioverter-defibrillator randomized trial in patients with nonischemic dilated cardiomyopathy and asymptomatic nonsustained ventricular tachycardia. AMIOVIRT. J Am Coll Cardiol 2003 41 1707-1712. 

Singh SN, Poole J, Anderson J, et al. Role of amiodarone or implantable cardioverter/defibrillator in patients with atrial fibrillation and heart failure. Am Heart J 2006 152(5) 974. e7-ll. 

Larsen GC, Manolis AS, Sonnenberg FA, et al. Cost-effectiveness of the implantable cardioverter-defibrillator effect of improved battery life and comparison with amiodarone therapy. J Am Coll Cardiol 1992 19 1323-34. 

Low doses (100-200 mg/d) of amiodarone are effective in maintaining normal sinus rhythm in patients with atrial fibrillation. The drug is effective in the prevention of recurrent ventricular tachycardia. It is not associated with an increase in mortality in patients with coronary artery disease or heart failure. In many centers, the implanted cardioverter-defibrillator (ICD) has succeeded drug therapy as the primary treatment modality for ventricular tachycardia, but amiodarone may be used for ventricular tachycardia as adjuvant therapy to decrease the frequency of uncomfortable cardioverter-defibrillator discharges. The drug increases the pacing and defibrillation threshold and these devices require retesting after a maintenance dose has been achieved. 

In a 62-year-old man with dilated cardiomyopathy and an implantable cardioverter defibrillator for ventricular tachycardia, microvolt T wave alternans differed when amiodarone was added (55). The onset heart rate with T wave alternans was lower and the alternans voltage higher with amiodarone than without it. 

FIGURE 1.6 Kaplan-Meier estimates of death from any cause in patients with both ischemic and nonischemic cardiomyopathy randomized to amiodarone, placebo, or implantable cardioverter-defibrillator therapy in SCD-HeFT. (From Ref. 29, with permission.)... 

A woman with congenital heart disease and atrial and ventricular arrhythmias managed by an implanted cardioverter defibrillator, epicardial pacing and amiodarone 400 mg daily, experienced deterioration in the control of her condition. She developed palpitations and experienced a shock from the defibrillator. Her amiodarone serum levels were 40% lower than 2 months previously, and her A-desethylamiodarone levels were undetectable. It was noted that 5 weeks earlier rifampicin 600 mg daily had been started to treat an infection of the pacing system. The amiodarone dose was doubled, but the palpitations continued. Amiodarone and A-desethy-lamiodarone levels increased after rifampicin was discontinued. Rifampicin is a potent enzyme inducer and it may have increased the metabolism and clearance of amiodarone. This case suggests that combined use of amiodarone and rifampicin should be well monitored. 

Ventricular fibrillation should be terminated by electrical defibrillation. Alternatively, lidocaine can be injected intravenously. In cases with lower frequency, ventricular tachyarrhythmia class I diugs such as aj marine, flecainide or propafenone are more effective as a result of the use-dependence of lidocaine. For prophylaxis treatment, amiodarone or sotalol may be helpful or the implantation of a cardioverter-defibrillator system. Acute amiodarone (i.v. in higher doses) can also terminate ventricular tachyarrhythmias. This action, however, seems to be mediated by its INa-blocking side effects and not (or less) by its class III like effects. 

Patients with hemodynamically significant ventricular tachycardia or ventricular fibrillation not associated with an acute Ml who are resuscitated successfully (electrical cardioversion, pressors, amiodarone) are at high risk for death and should receive implantation of an internal cardioverter-defibrillator. 

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