Influence of heart failure etiology on the effect of upgrading from right ventricular apical to biventricular or bifocal pacing in patients with permanent atrial fibrillation and advanced heart failure

INTRODUCTION Chronic heart failure (HF) results from various disease processes. There are no data on the effect of the etiology of HF on the improvement after pacemaker upgrade.
OBJECTIVES The aim of the study was to assess changes in various parameters in patients with ischemic (IC) and nonischemic (NIC) cardiomyopathy after pacemaker upgrade in pacemaker‑dependent patients with permanent atrial fibrillation, in the course of advanced HF during 12‑month follow‑up.
PATIENTS AND METHODS The study involved 34 patients who underwent an upgrade from right ventricular apical to biventricular or bifocal right ventricular pacing. In each patient, 12‑lead electrocardiography, transthoracic echocardiography, 6‑minute walking test, and the measurement of brain natriuretic peptide
levels were performed. Ischemic etiology of HF was confirmed in 25 subjects. The subgroups of cardiomyopathy were compared in terms of the improvement in relative and absolute values of the parameters at 6 and 12 months.
RESULTS At baseline, the subgroups did not differ significantly in demographic data and the measured parameters. All patients completed the first period of follow‑up showing clinical improvement after pacemaker upgrade. A significantly greater relative increase in the left ventricular ejection fraction was observed in the NIC subgroup at 6 months. The whole 12‑month follow‑up period was completed by a similar percentage of the IC and NIC patients (76% vs. 88.9%; P = 0.73). In the IC subgroup, a greater degree of mitral regurgitation was observed. 
CONCLUSIONS Patients with IC or NIC who underwent an upgrade from right ventricular apical to biventricular or bifocal right ventricular pacing and completed a 12‑month follow‑up did not differ in clinical improvement. Significant differences were observed in echocardiographic parameters.