Arrhythmia-induced cardiomyopathy: unveiled after electrical cardioversion

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Arrhythmia-induced cardiomyopathy (AIC) is an important cause of left ventricular (LV) dysfunction, confirmed by the reversal of cardiomyopathy after controlling the arrhythmia. It requires a high index of suspicion. Purpose To determine the prevalence and prognosis of AIC in patients referred to electrical cardioversion (EC) due to atrial fibrillation (AF) or atrial flutter (AFL). Methods We conducted a retrospective study encompassing patients referred to EC due to AF/AFL in our Cardiology Department, from September 2011 to September 2020. Clinical characteristics, echocardiographic studies and follow-up data were analysed. Reduced LV ejection fraction (LVEF) was defined as LVEF lower than 50%. Primary endpoints were all-cause mortality and cardiovascular (CV) death. We excluded patients with no information regarding LVEF before and after the EC. Results A total of 719 patients were referred to EC during the 9-year period, with a median age of 67 years-old and 70,4% male predominance. EC was successfully performed in 93,2%. Regarding patients with available LVEF data, only 123 patients (28,9%) had reduced LVEF before EC. Of these, 24,4% of patients were diagnosed with AFL, 59,3% had arterial hypertension, 26,9% were obese, 24,4% had ischemic heart disease and 7,3% had sleep apnea. Persistent AF/AFL was identified in 60,3%, 23,1% presented with first diagnosed AF/AFL and 15,7% had paroxysmal episodes. 57 patients (46,3%) had documented reversal of LV dysfunction after EC (improvement of a median LVEF of 41% to 59% after EC), confirming AIC diagnosis. Comparing to patients who did not recover LV function after EC, AIC patients had a larger prevalence of persistent AF/AFL (75% vs 45,2%; p=0,01), were more frequently cardioverted in an outpatient setting (68,4% vs 46%; p=0,047) and had lower prevalence of ischemic heart disease (5,3% vs 42,9%; p<0,001) and stroke (1,8% vs 12,7%; p=0,023). They also had lower values of CHA2DS2-VASc (2,23 vs 3,19; p<0,001) and HAS-BLED scores (0,6 vs 1,03; p=0,005) scores and were more treated with direct oral anticoagulants (77,8% vs 54,5%; p=0,01) than vitamin K antagonists. 64,6% remained in sinus rhythm one year after EC (vs 42,6%; p=0,026). During a median follow-up of 1338 days, no significant differences were found regarding all-cause mortality, but we report a lower rate of CV death in AIC patients (3,8% vs 25,5%; p=0,002). Conclusion In our study, 46,3% of patients with reduced LVEF had AIC, which was associated with a significantly lower rate of CV death. Given the prognostic impact of this diagnosis, EC should be considered as a primary strategy in patients with high suspicion of AIC due to AF/AFL.