Significant effects of atrioventricular node ablation and pacemaker implantation on left ventricular function and long-term survival in patients with atrial fibrillation and left ventricular dysfunction

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Abstract

Control of ventricular rate by atrioventricular node ablation and pacemaker implantation in patients with drug-refractory atrial fibrillation (AF) is associated with improved left ventricular (LV) function. The objective of this study was to determine the effect of atrioventricular node ablation on long-term survival in patients with AF and LV dysfunction. Survival was determined by the Kaplan-Meier method for 56 study patients with LV ejection fraction (EF) ≤40% who underwent atrioventricular node ablation and pacemaker implantation and 56 age- and gender-matched control patients with AF and LVEF >40%, and age- and gender-matched control subjects from Minnesota. Groups were compared using the log-rank test. In study patients (age 69 ± 10 years; 45 men), LVEF was 26% ± 8% and 34% ± 13% (p <0.001) before and after ablation, respectively. During follow-up (40 ± 23 months), 23 patients died. Observed survival was worse than that of normal subjects (p <0.001) and control patients (p = 0.005). After ablation, LVEF nearly normalized (≥45%) in 16 study patients (29%), in whom observed survival was comparable to that of normal subjects (p = 0.37). Coronary artery disease, hyperlipidemia, chronic renal failure, previous myocardial infarction, and coronary artery operation were independent predictors for mortality. Near normalization of LVEF occurred in 29% of study patients, suggesting that AF-induced EF reduction is reversible in many patients. Normal survival in patients with reversible LV dysfunction highlights potential survival benefits of rate control. Poor survival in patients with persistent LV dysfunction confirms the importance of optimal medical therapy.

Section snippets

Study group

The study group consisted of 56 patients with drug-refractory paroxysmal, permanent, or chronic AF and LV dysfunction (EF ≤40%) who underwent atrioventricular node ablation and pacemaker implantation between July 1990 and December 1998. This group of patients was drawn from a total of 350 patients who underwent the procedure during this period.

Control groups

A group of control patients consisted of 56 age- and gender-matched patients with AF and LVEF >40% who underwent atrioventricular node ablation and

Demographic characteristics

The baseline characteristics of the study and control patients are compared in Table 1. In addition to data presented in Table 1, right-sided ablation was performed in all study patients except 1, in whom a retrograde aortic approach was used. A rate-responsive ventricular pacemaker was implanted in 61% of patients, and a dual-chamber rate-responsive pacemaker was implanted in 39%. Before ablation, 3 patients had cardiac arrest; after ablation, cardiac arrest was documented in only 1 patient.

Discussion

Our study demonstrated that: (1) observed survival was significantly worse in study patients than in age- and gender-matched control patients with an LVEF >40%; (2) observed survival was significantly worse in study patients than in age- and gender-matched normal control subjects drawn from the Minnesota population; (3) near normalization of LVEF (≥45%) occurred in 29% of study patients, suggesting that AF-induced reduction in LVEF is reversible in a marked subset of patients; (4) observed

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