Diagnostic approach and treatment strategy in tachycardia-induced cardiomyopathy

Background: Due to the absence of differential guidelines for heart failure with tachyarrhythmia, it is difficult to diagnose tachycardia-induced cardiomyopathy (TIC) at the initial visit. Furthermore, clinical outcomes of rate versus rhythm control in TIC are unclear. Hypothesis: Because the etiology of TIC is different from dynamic cardiomyoplasty (DCMP), differential parameters may be present. Methods: We assessed 21 patients with TIC (15 men; mean age, 50 ± 14 years) and 21 control patients with idiopathic DCMP. We assessed clinical courses, echocardiographic parameters, as well as outcomes by treatment. Results: In the TIC group, the related tachyarrhythmias were atrial fibrillation (n = 12), atrial flutter (n = 5), atrial tachycardia (n = 3) and paroxysmal supraventricular tachycardia (n = 1). After treatment, all patients became asymptomatic and the ejection fraction (EF) improvement (ΔEF ≥ 15%) was observed in all patients (left ventricular ejection fraction [LVEF], 30 ± 11%_initial versus 58 ± 6%_last). In the idiopathic DCMP group, no patient showed EF improvement (EF increase ≤ 5%), and 4 patients (19%) underwent heart transplantation. Left ventricle (LV) mass indices, volumes adjusted by BSA, and dimensions were smaller in the TIC group than in the idiopathic DCMP group. Of those, LV end-diastolic dimension was the only independent predictor of TIC in multiple regression analysis (odds ratio [OR] 0.742 per 1 mm, 95% confidence ratio [CI] 0.618 to 0.891, p = 0.001). The Association of University Cardiologists (AUC) was 0.908 on receiver-operating characteristic (ROC) curve analysis and LV end-diastolic dimension ≤ 61 mm could predict TIC with a sensitivity of 100% and a specificity of 71.4%. After restoration of sinus rhythm (n = 8), one experienced recurrent TIC after discontinuation of amiodarone. After control of heart rate (n = 13), one experienced recurrent TIC due to poor control of heart rate (log-rank test, p = 0.808). There were no differences in the echocardiographic parameters between the 2 groups before and after treatment except for the larger initial LV volumes in the rhythm control. Conclusions: In patients presented as heart failure with tachyarrhythmia, initial echocardiographic parameters, especially LV end-diastolic dimension, help to differentiate TIC from idiopathic DCMP. Rate control was as effective as rhythm control for EF improvement and prognosis.