Physiological stimulation in preserved ejection fraction: A randomized trial

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Right ventricular stimulation in the apex (RVAS) produce dysynchrony, leading to left ventricle systolic dysfunction (LVSD) in some cases. Circumstances that can worsen the LVSD are a high burden of RVAS, and the presence of previous LVSD and/or intraventricular conduction disease (IVCD). Direct activation of the specialized conduction system with physiological stimulation (PS) can preserve this physiological pattern and shorten de QRS when the impairment is proximal to the pacing site. Most of the studies with PS has been focused on patients with LVSD, with few and scarce evidences regarding pacients without LVSD. Objectives and methods This is a parallel, single blinded, unicentric, randomized trial of patients with preserved of mild reduced left ventricular ejection fraction (LVEF) submitted to a pacemaker implantation due to atrioventricular block (AVB), with previous IVCD (wide QRS) an anticipated high rate of ventricular pacing. Patients were randomized 1:1 to RVAS vs PS and followed for 6 months. Clinical, ECG, echocardiography and analytic parameters were compared. The primary endpoint was the change in the LVEF at 6 months in each group. The secondary endpoints were the changes in the left ventricular end-diastolic diameter (LVEDD), the QRS duration, the pro–B-type natriuretic peptide (NT-proBNP), the NYHA class, and the Minnesota Living with Heart Failure Questionnaire (MLWHFQ) in each group. Results The study included 57 patients of 77±9,6 years. Of all patients, 53% were treated with RVAS and 47% with PS. There were 2 patients with crossover to RVAS for technical difficulties and 1 patient with crossover to PS due to apical scar. There were no differences in the basal QRS duration (142.08±20,2 ms), LVEF (58.87±7,2%), NT-proBNP (3336,03±7258,68 pg/ml), or MLWHFQ (22,19±14,68), between both groups (Table 1). Acutely significant differences were observed in the change of QRS duration among groups (+16±29 ms in the RVAS group vs -17±25 ms in the PS group, p<0,001). At 6 months follow-up LVEF showed a non-significant reduction of 0.8±1.1% in the PS group compared to a significant reduction of 5.1±1.7% in the RVAS group (difference 4,26% IC 0,1-8,43 p=0,022). No differences were observed regarding the values of the NT-ProBNP and the MLWHFQ between groups at 6 months (Table 2). Conclusions In patients with preserved LVEF requiring pacemaker implantation for AVB, PS shorten the QTS duration and preserves the LVEF compared to RVAS.