Echocardiographic Evaluation of LV Function in Patients with Tachyarrhythmia and Reduced Left Ventricular Function in Response to Rhythm Restoration

Aims: Tachyarrhythmia due to atrial fibrillation (AF) is often associated with reduced left ventricular (LV) function and has been proposed to cause arrhythmia-induced cardiomyopathy (AIC). However, the precise diagnostics of AIC and reversibility after rhythm restoration are poorly understood. Our aim was to investigate systolic LV function in tachycardic AF and to evaluate the direct effect of rhythm restoration. Methods: We prospectively studied 24 patients (71% male, age 65 ± 9 years) with tachycardic AF and newly diagnosed reduced left ventricular ejection fraction (LVEF). Just before and immediately after electrical cardioversion (ECV), transthoracic echocardiography was performed. Geometric as well as functional data were assessed. Results: Patients presented with a heart rate (HR) of 117.4 ± 21.6/min and a 2D-/3D-LVEF of 32 ± 9/31 ± 8%. ECV to sinus rhythm normalized HR to 77 ± 11/min with an increase of 2D-/3D-LVEF to 37 ± 9/37 ± 10% (p < 0.01 vs. baseline, each). Left ventricular geometry changed with an increase of end-diastolic volume (LVEDV) while end-systolic volume (LVESV) remained unchanged. Parameters concerning myocardial deformation (global longitudinal strain (GLS), strain rate (SR)) decreased whereas the RR interval-corrected GLS (GLSc) remained unchanged. In a simple linear regression model, GLS correlated with 2D- and 3D-LVEF not only before (pre) ECV, but also after (post) ECV. We demonstrate that the increase of LVEF and GLS (ratios pre/post) correlates with the change of HR (ΔHR; R(2) = 0.20, 0.33 and 0.32, p < 0.05 each), whereas ratios of GLSc and SR do not significantly correlate with HR (R(2) = 0.03 and 0.01, p = n.s. each). Conclusion: In patients with tachyarrhythmia and reduced ejection fraction, ECV leads to immediate improvement in EF and GLS while HR-corrected LV contractility remains unchanged. This suggests that the immediate effects of rhythm restoration are mostly related to changes in left ventricular volume, but not to an acute improvement of heart-rate independent contractility.