Abstract 13940: Risk Stratification of Future Left Ventricular Dysfunction in Patients With Indications for Right Ventricular Pacing Owing to Bradycardia

Abstract

Background: Although right ventricular (RV) pacing is the only effective treatment for patients with symptomatic atrioventricular block, it creates left ventricular (LV) mechanical dyssynchrony, which can induce LV dysfunction and heart failure. Current criterion for consideration of cardiac resynchronization therapy (CRT) is LV ejection fraction (LVEF) ≤35%, but indication for CRT in patients required for RV pacing with LVEF >35% remains uncertain. Methods: We studied 35 consecutive patients with LVEF of 51±9% (all≥35%) who had undergone implantable cardioverter-defibrillator implantation (RV pacing <5%). Echocardiography was performed at baseline and during RV pacing. LV dyssynchrony was determined by the anteroseptal-to-posterior wall delay from mid-LV short-axis view using two-dimensional speckle-tracking radial strain (≥130ms as significant). Patients were divided into two groups based on baseline LVEF: preserved LVEF≥50% (n=19) and mildly reduced LVEF of 35-50% (n=16). Results: LV dyssynchrony in patients with mildly reduced LVEF was significantly worsened during RV pacing compared to that in patients with preserved LVEF (from 86.0±103.9ms to 214.6±132.1ms vs. from 21.7±29.0ms to 65.6±90.9ms, p=0.01). Furthermore, the prevalence of significant LV dyssynchrony during RV pacing in patients with mildly reduced LVEF was significantly higher than that in patients with preserved LVEF (68% vs. 16%, p<0.01). LVEF in patients with mildly reduced LVEF was also significantly worsened during RV pacing compared to that in patients with preserved LVEF (from 42.8±4.6% to 37.6±6.8% vs. from 58.3±5.7% to 57.9±6.9%, p<0.01). Conclusions: The amount of RV pacing-induced LV dysfunction may be associated with baseline LV function. Thus, these adverse effects in patients with mildly reduced LVEF of 35-50% and indications for RV pacing owing to bradycardia can be prevented by CRT.