Background: Arrhythmia-induced cardiomyopathy (AIC) is a condition in which arrhythmia leads to left ventricular systolic dysfunction (LVSD) and heart failure. We aimed to determine (a) the prevalence of AIC in patients with newly diagnosed LVSD and concomitant tachyarrhythmia, (b) the time required for LVEF recovery and (c) to identify potential predictors of AIC.

Method: Sixty-eight consecutive patients with otherwise unexplainable LVSD (left ventricular ejection fraction (LVEF) <50%) and tachyarrhythmia (atrial fibrillation/flutter + heart rate >100/min) were prospectively enrolled, received effective rhythm restoration, and were followed up after 2, 4, and 6 months including clinical characteristics, biomarker assessment and imaging. Left ventricular scar was quantified by late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging. 18 Patients were excluded, mostly because of recurrent arrhythmia. AIC was diagnosed ex juvantibus at the end of follow-up when LVEF increased either by ≥15% or by ≥10% and above 50%.

Results: AIC was diagnosed in 41 of 50 patients, resulting in a prevalence of 82%. Most of the LVEF recovery occurred in the first 2 months after rhythm control: in AIC patients, LVEF increased from 35.4±8.2% to 52.7±8.0% (p<0.001) vs. 37.0±9.5% to 43.3±7.0% (p=0.005) in non-AIC patients. From month 2 to the end of follow-up, LVEF further increased to 57.2±6.1% in AIC (p<0.001 vs. 2 months), but not in non-AIC patients (44.0±7.8%, p=0.628 vs. 2 months). This favors a prolonged follow-up to 6 months after rhythm control. In addition, LVEDD was shown to be a robust predictor of AIC in logistic and Cox regression analysis (Tables 1, 2). The optimal cut-off was a LVEDD of 56.5mm (AUC=0.82) with smaller values favoring AIC. Biomarkers and percentage of LGE did not differ between the groups.

Conclusion: In patients with newly diagnosed left ventricular dysfunction and tachyarrhythmia, the prevalence of AIC was very high, and LVEDD was predictive of AIC. The time course of LVEF recovery suggests that most of the recovery takes place in the first few months after rhythm control, but the definite diagnosis of AIC cannot be made until 6 months.