1 Introduction
Tachycardia-induced cardiomyopathy (TCM) is a reversible cause of heart failure with impaired left ventricle (LV) function. Atrial fibrillation (AF) is the most common cause.1 We cannot always observe echocardiographic data in typical TCM at the first occurrence: LV ejection fraction (LVEF) is <30%, LV end-diastolic diameter is <65 mm, and LV end-systolic diameter is <50 mm. The diagnosis is determined by a recovery of LV function within 3 months after treatment or control of the arrhythmia.2 In other words, we cannot determine the diagnosis for at least 3 months after arrhythmia control. Moreover, the diagnosis is determined by excluding other causes of cardiomyopathy, especially idiopathic dilated cardiomyopathy (DCM). Cardiac magnetic resonance (CMR) imaging has been useful for excluding other causes.3 However, it is an unusual method and is difficult for patients with impaired renal function.
Thus, the purpose of this study was to clarify the characteristics of TCM before AF ablation. These should help establish early and optimal examinations, such as transesophageal echocardiography or enhanced computed tomography (CT), and treatments, such as AF ablation or cardioversion.
2 Methods
2.1 Study population