Background: Arrhythmia-induced cardiomyopathy (AIC) is a reversible cause of heart failure triggered by irregular and/or tachycardic heart rates. Little is known about the disease frequency, time course of recovery of left ventricular (LV) and right ventricular (RV) systolic function and possible predictors regarding this condition. Thus, we aimed to determine these parameters in our study.

Methods: Sixty-eight consecutive patients with unexplainable LVSD (left ventricular ejection fraction (LVEF) <50%) and tachyarrhythmia (atrial fibrillation/flutter + heart rate >100/min) were prospectively enrolled at 3 different centers. After successful rhythm restoration, patients 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 per protocol, 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%. If these criteria were not met, non-AIC was diagnosed.

Results: Of the 50 patients included in our study, AIC was diagnosed in 41 of 50, resulting in a disease frequency of 82%. Within the first 2 months after rhythm control, most patients already showed recovered LV function. In patients with AIC, LVEF increased from 35.4±8.2% to 52.7±8.0% vs. 37.0±9.5% to 43.3±7.0% in non-AIC patients. From month 2 to the end of follow-up, LVEF further increased to 57.2±6.1% in the AIC group, but not in non-AIC group (44.0±7.8%). RV function determined by measurement of tricuspid annular plane systolic excursion (TAPSE) was initially impaired in patients with AIC and normalized after rhythm restoration already after 2 months (15.5±4.8 mm to 20.1±4.2 mm) (figure 1). Multivariable logistic regression analysis indicated that a smaller LV end-diastolic diameter (LVEDD) at baseline could be a possible parameter for diagnosing AIC at an early stage. Biomarkers and percentage of LGE did not differ between the groups.

Conclusion: In this clinical cohort, a high frequency of AIC could be detected, underlying the importance of this disease in daily clinical practice. Recovery of LV and RV function in patients with AIC predominantly takes place in the first 2 months after rhythm control therapy. As further recovery of LVEF is delayed in some patients, the final diagnosis of AIC should be made after 6 months. LVEDD at baseline is a potential parameter for early identification of AIC.

Fig. 1: (A) Bar graph showing the frequecncy of patients who were diagnosed with AIC or non-AIC. After 6 months, 82% of patients met the AIC-criteria. (B) Scatter plot demonstrating the time course of LV function for the AIC and non-AIC group. Dotted (solid) lines connect the mean values for the AIC (non-AIC) group. ** p <0.0001 vs. 0 months, * p <0.05 vs. 0 months, §§ p <0.001 vs. 6 months, § p <0.05 vs. 6 months, ## p <0.01 vs. the respective AIC group, # p <0.05 vs. the respective AIC group. AIC = arrhythmia-induced cardiomyopathy, AF = atrial fibrillation or atrial flutter, LVEF = left ventricular systolic function, SR = sinus rhythm.