Advantages and Pitfalls of Combining Device-Based and Pharmacologic Therapies for the Treatment of Ventricular Arrhythmias:. Observations from a Tertiary Referral Center

Adjuvant antiarrhythmic therapy in patients with implantable cardioverter defibrillators

The risk of sudden cardiac death from ventricular fibrillation or ventricular tachycardia in patients with cardiomyopathy related to structural heart disease has been favorably impacted by the wide adaptation of implantable cardioverter defibrillators (ICDs) for both primary and secondary prevention. Unfortunately, after ICD implantation both appropriate and inappropriate ICD therapies are common. ICD shocks in particular can have significant effects on quality of life and disease-related morbidity and mortality. While not indicated for primary prevention of ICD therapies, beta-blockers and antiarrhythmic drugs are a cornerstone for secondary prevention of them. This review will summarize our current understanding of adjuvant antiarrhythmic drug therapy in ICD patients. The review will also discuss the roles of nonantiarrhythmic drug approaches that are used in isolation and in combination with antiarrhythmic drugs to reduce subsequent risk of ICD shocks.

Acute Antiarrhythmic Therapy of Ventricular Tachycardia and Ventricular Fibrillation

Ventricular arrhythmias (ventricular tachycardia and ventricular fibrillation) are often associated with underlying structural heart disease and require prompt assessment and treatment. Acute treatment involves initial hemodynamic stabilization of the patient followed by suppressive treatment with pharmacologic and nonpharmacologic approaches for reducing the risk of recurrence of ventricular arrhythmias and potential development of sudden cardiac death. This article reviews acute antiarrhythmic drug therapy for ventricular arrhythmias based on the clinical presentation.

Indications for internal cardioverter defibrillator implantation predict time to first shock and the modulating effect of beta-blockers

BACKGROUND

Patients receive implantable cardioverter defibrillator (ICD) for varying indications. Whether these indications influence the time to first ICD shock is suspected but not confirmed. The modulating effect of beta-blockers on shock-free survival is not fully elucidated.

METHOD

A retrospective analysis of 230 consecutive patients (age 63 +/- 14 years, 79% men, 75% ischemic, 70% beta-blockers) implanted with an ICD was performed. Patients were divided into 4 groups depending on the ICD indication: groups A (secondary prevention of sudden death), B (left ventricular ejection fraction < or = 35% and positive electrophysiology study [EPS]), C (left ventricular ejection fraction < or = 35% and negative EPS or no EPS performed), and D (patients who did not meet inclusion criteria for groups A, B, or C). Time to shock was analyzed by the Kaplan-Meier method.

RESULTS

During a mean follow-up of 489 +/- 280 days, 57 (24.7%) patients received 82 shocks (49% appropriate). The 1-year shock-free survival for patients in groups A, B, C, and D were 57%, 77%, 79%, and 91%, respectively (P = .03), for total shocks and 75%, 92%, 92%, and 100%, respectively (P = .007), for appropriate shocks. For patients in group A, the use of beta-blockers increased the 1-year shock-free survival from 48% to 61% for total shocks and from 65% to 79% for appropriate shocks.

CONCLUSION

Time to first shock is determined by the indication for ICD implantation and is not predicted by the results of EPS. Patients with secondary indications for ICD implantation are at highest risk of shocks and may deserve consideration for prophylactic antiarrhythmic drugs. beta-Blockers increase the time to first ICD shock in patients implanted for secondary prevention of sudden death.

Approach to antiarrhythmic therapy in patients with ICDs and frequent activations

Patients with an implantable defibrillator may require concomitant antiarrhythmic drug therapy to reduce therapy from the device, especially shocks from the device. New evidence suggests that amiodarone, in combination with b-blockade, is the most effective treatment to reduce the frequency of defibrillator therapies, but sotalol and azimilide have also been shown to be effective. Electrical storm is a serious condition that occurs in 20% of patients living with a defibrillator, and its management requires a complex approach to the patient.