Background Dual-chamber pacemakers have been in use for more than 15 years. Although they may confer a physiological advantage over single-chamber Ventricular pacemakers, they are more expensive and have a generally shorter service life than single-chamber devices. We carried out the present study to identify patient subgroups who were preferentially receiving greater or lesser proportions of dual-chamber devices and to determine whether the selection of different types of pacemakers was associated with differences in mortality. Methods and Results We analyzed a 20% random national sample of all Medicare beneficiaries aged 65 years or older who underwent initial placement of a permanent pacemaker and were discharged in 1988, 1989, or 1990 (n=36312). The minimum follow-up for vital status was 1 year. The relation of pacemaker type to patient and provider characteristics was determined using logistic regression analysis. The relation between pacemaker type and mortality was determined using the Cox proportional hazards method. The proportion of dual-chamber systems that were received increased from 27.2% in 1988 to 37.0% in 1990 (P<.001). Dual-chamber pacemaker recipients were younger (P<.001) than ventricular pacemaker recipients. Other independent correlates of dual-chamber pacemaker selection included male sex (odds ratio and 95% confidence intervals, 1.18 and 1.12 to 1.24, respectively), atrioventricular block (1.59 and 1.51 to 1.67), congestive heart failure (1.14 and 1.08 to 1.20), atrial fibrillation (0.36 and 0.34 to 0.39), and the presence of a major noncardiac diagnosis (0.86 and 0.83 to 0.89). Nonmedical predictors of dual-chamber pacemaker selection included Medicaid eligibility (0.78 and 0.71 to 0.86), implantation in the western United States (1.19 and 1.10 to 1.29), implantation by a rural provider (0.70 and 0.65 to 0.76), hospitalization in a 500-bed-or-larger hospital (1.20 and 1.13 to 1.28), hospitalization in a private hospital (1.19 and 1.10 to 1.28), or hospitalization in a hospital with a catheterization laboratory (1.47 and 1.38 to 1.56). Dual-chamber pacemaker selection was an independent predictor of survival at 1 year (0.82 and 0.77 to 0.87) and at 2 years (0.82 and 0.77 to 0.87) after controlling for potentially confounding patient-level and hospital-level characteristics. Conclusions The present study describes important variations in the clinical practice of cardiac pacing, many of which are not based on clinical characteristics. Furthermore, the selection of a dual-chamber pacemaker is associated with increased survival. These results underscore the need for prospective, outcome-based clinical trials of pacemaker mode selection.
