Clinical characteristics of patients intolerant to VVIR pacing

The incidence and clinical predictors of the development of intolerance to VVIR pacing have not been extensively studied in prospective long-term rand omized trials comparing different pacing modes. The frequency and clinical factors predicting intolerance to ventricular pacing are controversial. The Pacemaker Selection in the Elderly (PASE) Trial enrolled 407 patients aged greater than or equal to 65 years in a 30-month, single-blind, randomized, controlled comparison of quality of life and clinical outcomes with ventri cular pacing and dual-chamber pacing in patients under-going dual-chamber p acemaker implantation for standard clinically accepted indications. We revi ewed the clinical, hemodynamic, and electrophysiologic variables at the tim e of pacemaker implantation in 204 patients enrolled in the PASE trial and randomized to the VVIR mode, some of whom subsequently required cross-over (reprogramming) to DDDR pacing. During a median follow-up of 555 days, 53 p atients (26%) crossed over from VVIR to DDDR pacing. A decrease in systolic blood pressure during ventricular pacing at the time of pacemaker implanta tion (p = 0.001), use of beta blockers at the time of randomization (p = 0. 01), and nonischemic cardiomyopathy (p = 0.04) were the only variables that predicted crossover in the Cox multivariate regression model. After reprog ramming to the dual-chamber mode, patients showed improvement in all aspect s of quality of life, with significant improvements in physical and emotion al role. The high incidence of crossover from VVIR to DDDR pacing along wit h significant improvements in quality of life after crossover to DDDR pacin g strongly favors dual-chamber pacing compared with single-chamber ventricu lar pacing in elderly patients requiring permanent pacing. (C) 2000 by Exce rpta Medica, Inc.