The Role of Pacing Modality in Determining Long-Term Survival in the Sick Sinus Syndrome

doi:10.1059/0003-4819-119-5-199309010-00002

The Role of Pacing Modality in Determining Long-Term Survival in the Sick Sinus Syndrome

From the Cleveland Clinic Foundation, Cleveland, Ohio. Requests for Reprints: Elena B. Sgarbossa, MD, Department of Cardiology, Desk F15, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195. Acknowledgments: The authors thank Lon W. Castle, MD, Bruce L. Wilkoff, MD, Victor A. Morant, MD, and Tony W. Simmons, MD, for their clinical work, which made possible the careful analysis of a large number of pacemaker implants; Richard G. Trohman, MD, for his review of the manuscript and suggestions; Marlene Goormastic, MPH, and David Miller, MS, for their collaboration in the statistical analysis of the data; and John Frater, Jr., for his cooperation in the data collection. Grant Support: In part by grants from Keith Benson Memorial Fund and DuPont Pharmaceuticals, Wilmington, Delaware.

Abstract

Objective: To determine whether the atrial-based pacing modalities (physiologic pacing) improve survival when compared with single-chamber ventricular pacing in patients with the sick sinus syndrome.

Design: Retrospective, nonrandomized study.

Setting: A tertiary care teaching hospital.

Patients: A total of 507 patients with a mean age of 66 years who received an initial pacemaker for the sick sinus syndrome between January 1980 and December 1989. Pacing modes were ventricular (22%), atrial (4%), and dual-chamber (74%).

Measurements: Total and cardiovascular mortality rates. Mean follow-up was 66 months.

Results: Independent predictors of total mortality by the Cox proportional-hazards model were 1) New York Heart Association functional class [hazard ratio =1.67/class; 95% CI, 1.31 to 2.11]; 2) age [hazard ratio = 1.62/12-year increment; CI, 1.28 to 2.05]; 3) peripheral vascular disease [hazard ratio = 2.21; CI, 1.42 to 3.42]; 4) bundle branch block [hazard ratio = 2.04; CI, 1.33 to 3.13]; 5) coronary artery disease [hazard ratio = 1.66; CI, 1.15 to 2.39]; and 6) valvular heart disease (hazard ratio = 1.71; CI, 1.08 to 2.69). The same variables were independent predictors of cardiovascular mortality, with cerebrovascular disease reaching borderline statistical significance (hazard ratio = 1.69; CI, 1.00 to 2.86). Using univariate analysis, single-chamber ventricular pacing had more than 40% increased risk for both total and cardiovascular death, but the difference was of borderline statistical significance (total mortality: P = 0.053; hazard ratio = 1.43; CI, 0.99 to 2.07; cardiovascular mortality: P = 0.15; hazard ratio = 1.41; CI, 0.87 to 2.29).

Conclusions: Because the role of the ventricular pacing mode as a long-term predictor of total and cardiovascular mortality remains inconclusive, a large, randomized study is necessary to confirm whether physiologic pacing provides a substantial reduction in mortality when compared with ventricular pacing.