Pacing From the Right Ventricular Septum and Development of New Atrial Fibrillation in Paced Patients With Atrioventricular Block and Preserved Left Ventricular Function.

Background: Whether pacing from the right ventricular (RV) septum improves prognosis is unclear. Furthermore, the clinical characteristics of patients who develop atrial fibrillation (AF) and cardiovascular events during long-term RV septal pacing have not been described.Methods and Results:We retrospectively evaluated the incidence of AF and cardiovascular events, including cardiac death, heart failure requiring hospitalization, or stroke, for a median of 4.0 years in 123 recipients of dual-chamber pacemakers implanted for atrioventricular block with preserved left ventricular function, who were free from AF before device implantation. AF developed in 30 patients (24%), and multivariable analysis suggested that the cumulative percentage of RV pacing was the only independent predictor of newly developed AF (hazard ratio: 1.19 for each 10% increment; 95% confidence interval: 1.04-1.41; P=0.01). Furthermore, older age, newly developed AF and a paced QRS duration ≥155 ms at pacemaker implantation were significant predictors of cardiovascular events.

Conclusions: RV septum pacing may induce AF in up to one-quarter of patients paced for atrioventricular block, according to the frequency of pacing. More importantly, in such patients, AF induced by RV pacing and a paced QRS duration ≥155 ms at pacemaker implantation are significantly associated with poor prognosis. Therefore, we recommend pacing from sites producing a paced QRS duration <155 ms and avoiding unnecessary RV pacing. (Circ J 2016; 80: 2302-2309).