Long-Term Impact of Right Ventricular Pacing on Left Ventricular Systolic Function in Pacemaker Recipients With Preserved Ejection Fraction: Results From a Large Single-Center Registry

Abstract

Background: There is limited evidence of long-term impact of right ventricular pacing on left ventricular (LV) systolic function in pacemaker recipients with preserved LV ejection fraction (LVEF). The objective of the study was to evaluate the outcome and echocardiographic course of baseline preserved LVEF in a large cohort of pacemaker recipients with respect to pacing indication and degree of right ventricular pacing.

Methods and results: We enrolled 991 patients (73±10 years, 54% male) with baseline normal (>55%) LVEF (n=791) or mildly reduced (41-55%) LVEF (n=200) who had paired echocardiographic data on LV systolic function recorded at implantation and last follow-up. According to pacing indication, patients were divided into atrioventricular block group A (n=500) and sinus node disease group B (n=491). Main outcome measures were all-cause mortality and deterioration of LV function ≥2 LVEF categories at last follow-up. Patients were followed for an average of 44 months. Death from any cause occurred in 166 (17%), and deterioration of LV function ≥2 LVEF categories in 56 (6%) patients. There was no significant difference in outcome between group A and group B either in patients with normal LVEF or in those with mildly reduced LVEF. Mean percentage of right ventricular pacing was not predictive of outcome.

Conclusions: In a large cohort of pacemaker recipients with predominantly normal LVEF, clinically relevant LV dysfunction develops rather infrequently. No significant difference in all-cause mortality and development of severe LV dysfunction is observed between patients with atrioventricular block and sinus node disease. Accordingly, de novo biventricular pacing cannot be recommended for patients with preserved LVEF.

Keywords: bradycardia; cardiac resynchronization therapy; heart failure; left ventricular ejection fraction; pacemaker; right ventricular pacing; ventricular dyssynchrony.

Figure 1

Study enrollment and patient population. ^#Exclusion criteria were baseline reduced LVEF ≤40%, indication for an ICD or CRT device, and lack of paired echocardiographic data recorded at baseline and follow‐up. According to pacing indication and anticipated degree of RV pacing, patients were classified into 2 groups: group A, patients with AV block (AVB cohort), and group B, patients with sinus node disease (SND cohort). LV‐0, baseline normal LVEF (>55%); LV‐1, baseline mildly reduced LVEF (41% to 55%). AV indicates atrioventricular; AVB, atrioventricular block; CRT, cardiac resyncynchronization therapy; ICD, implantable cardioverter‐defibrillator; LV, left ventricular; LVEF, left ventricular ejection fraction; RV, right ventricular; SND, sinus node disease.

Figure 2

Echocardiographic follow‐up of LV systolic function in patients with baseline normal LVEF (LV‐0) and baseline mildly reduced LVEF (LV‐1). Presented is the percentage (plus 95% CI) of patients in each LVEF category assessed at time of last follow‐up. LV‐0: LVEF >55%; LV‐1: LVEF 41% to 55%; LV‐2: LVEF 31% to 40%; LV‐3: LVEF ≤30%. LV indicates left ventricular; LVEF, left ventricular ejection fraction.

Figure 3

Echocardiographic follow‐up of LV systolic function in group A and group B patients with baseline normal LVEF (LV‐0) (upper panel) and baseline mildly reduced LVEF (LV‐1) (lower panel). There was no significant difference in the course of LV systolic function between group A and group B patients with (LV‐1; P=0.12) and without (LV‐0; P=0.58) baseline mildly reduced LVEF. Presented is the percentage (plus 95% CI) of patients in each LVEF category assessed at time of last follow‐up. LV‐0: LVEF >55%; LV‐1: LVEF 41% to 55%; LV‐2: LVEF 31% to 40%; LV‐3: LVEF ≤30%. LV indicates left ventricular; LVEF, left ventricular ejection fraction.

Figure 4

Cumulative survival of all patients (left), patients with baseline normal LVEF (middle), and patients with baseline mildly reduced LVEF (right) according to pacing indication group. Group A, patients with atrioventricular block (AVB cohort); group B, patients with sinus node disease (SND cohort). Log‐rank test, ns for all 3 survival analyses as indicated. LV indicates left ventricular; LVEF, left ventricular ejection fraction; ns, not significant.

Figure 5

Freedom from deterioration of LV systolic function ≥2 LVEF categories during follow‐up in all patients (left), patients with baseline normal LVEF (middle), and patients with baseline mildly reduced LVEF (right) according to pacing indication group. Group A, patients with atrioventricular block (AVB cohort); group B, patients with sinus node disease (SND cohort). Log‐rank test, ns for all 3 survival analyses as indicated. LV indicates left ventricular; LVEF, left ventricular ejection fraction; ns, not significant.