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 (DeltaEF>or=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<or=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<or=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.