Mechanisms and Clinical Significance of Arrhythmia-Induced Cardiomyopathy.

Arrhythmia-induced cardiomyopathy (AIC) is characterized by left ventricular systolic dysfunction for which the primary cause is arrhythmia. The hallmark of AIC is its reversibility once the arrhythmia is properly controlled. Any tachyarrhythmia can potentially cause AIC (often called "tachycardiomyopathy"), with atrial fibrillation (AF) being by far the most common in clinical practice. The pathophysiological mechanisms underlying AIC need further clarification, but the available evidence, principally from animal models, implicates metabolic dysfunction due to increased oxygen requirements, neurohormonal adaptive mechanisms, and cellular Ca2+ mishandling as important contributors. Tachycardia is a common denominator of most cases of AIC, but other components specific to the patient and the arrhythmia have been implicated. The diagnosis of AIC requires the exclusion of a primary causative role of other conditions such as hypertension, primary cardiomyopathies, and valve disease, which may require specific pharmacological and invasive therapies. Catheter ablation is emerging as a safe and effective alternative to antiarrhythmic medication and has an established role in the management of AIC. Recent studies showing improved cardiac function and mortality rates in patients with heart failure and concomitant AF dramatically illustrate the often-unrecognized scope of AIC and the potential benefits of interventional therapy. Major AF trials do not otherwise focus specifically on AIC, and careful analysis of the literature is necessary to appreciate the clinical characteristics and therapeutic implications. This contemporary review summarizes the current understanding of pathophysiological mechanisms underlying AIC, discusses the clinical implications, and offers a general approach to management, with a particular focus on AF-induced cardiomyopathy.