Key result
Single-chamber ventricular pacing was associated with a borderline increased risk of total mortality compared to atrial-based pacing in sick sinus syndrome.
Why the study?
Do atrial-based pacing modalities improve survival compared with single-chamber ventricular pacing in patients with sick sinus syndrome?
Cohort (n=507)
No
Do atrial-based pacing modalities improve survival compared with single-chamber ventricular pacing in patients with sick sinus syndrome?
In patients with sick sinus syndrome, the survival benefit of physiologic pacing over ventricular pacing remains inconclusive in this retrospective cohort, highlighting the need for randomized trials.
Answers are grounded in this paper and cite their sources.
Borderline mortality signal with ventricular pacing in sick sinus syndrome warrants caution; leaves open survival benefit of atrial-based pacing in this observational cohort.
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% Cl, 1.31 to 2.11); 2) age (hazard ratio = 1.62/12-year increment; Cl, 1.28 to 2.05); 3) peripheral vascular disease (hazard ratio = 2.21; Cl, 1.42 to 3.42); 4) bundle branch block (hazard ratio = 2.04; Cl, 1.33 to 3.13); 5) coronary artery disease (hazard ratio = 1.66; Cl, 1.15 to 2.39); and 6) valvular heart disease (hazard ratio = 1.71; Cl, 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; Cl, 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; Cl, 0.99 to 2.07; cardiovascular mortality: P = 0.15; hazard ratio = 1.41; Cl = 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.
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Elena B. Sgarbossa (1993) conducted a cohort in Sick sinus syndrome (n=507). Single-chamber ventricular pacing vs. Atrial-based pacing modalities ('physiologic pacing') was evaluated on Total mortality (HR 1.43, 95% CI 0.99-2.07, p=0.053). Single-chamber ventricular pacing was associated with a borderline increased risk of total mortality compared to atrial-based pacing in sick sinus syndrome.
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