<div>In this retrospective observational study, we observed 32 patients with
paroxysmal or persistent atrial fibrillation (AF) who had impaired LV
function without structural heart disease and who underwent catheter
ablation. We defined impaired LV function as LV ejection fraction (LVEF)
&lt;50%. After ablation, the LVEF became &lt;60% (Group
1; n = 11) or
60%
(Group 2; n = 21). We compared the differences in baseline
characteristics between the two groups. The patients in Group1 had no
ischemic disease. A receiver operating curve (ROC) with area under the
curve (AUC) was used to evaluate the prediction efficiency.</div><div>Results</div><div>There were significant differences in left atrial (LA) volume (LAV) and
LAV adjusted by body surface area (LAVI) measured by computed tomography
(CT) (p &lt; 0.05 for both). The AUCs were 0.810 and 0.823,
respectively. The points at which sensitivity and specificity were
maximum were 147 ml and 79. Small LAV and LAVI were predictors of LVEF
improvement.</div><div>Conclusion</div><div>Small LAV measured by CT before ablation may be useful for diagnosis of
TCM with AF.</div><div>Key words: Tachycardia-induced cardiomyopathy, Arrhythmia-induced
cardiomyopathy, atrial fibrillation, catheter ablation, heart failure</div><div>1 Introduction</div><div>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 &lt;30%,
LV end-diastolic diameter is &lt;65 mm, and LV end-systolic
diameter is &lt;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.</div><div>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.</div><div>2 Methods</div><div>2.1 Study population</div>