Syncope in Paced Patients With Sick Sinus Syndrome From the DANPACE Trial: Incidence, Predictors and Prognostic Implication

Study Questions:

What are the incidence, predictors, and prognostic implications of syncope in paced patients with sick sinus syndrome (SSS)?


A total of 1,415 patients (mean age 72.9 years, standard deviation [SD] 11.1) with SSS were randomized in the DANPACE study to either rate-responsive single-chamber pacing (AAIR; n = 707) or rate-responsive dual-chamber pacing (DDDR; n = 708). The main outcome measures were patient-reported syncope after pacemaker implantation and mortality.


Mean follow-up was 5.4 years (SD 2.6). A total of 247 (17.5%) patients experienced syncope after pacemaker implantation: 135 (19%) from the rate-responsive single-chamber pacing group, and 112 (15.8%) from the rate-responsive dual-chamber pacing group. Predictors of syncope post-pacemaker implantation included: age 0-39 years (hazard ratio [HR], 2.9; 95% confidence interval [CI], 1.4-6.3; p = 0.01; reference range, 60-79 years), age ≥80 years (HR, 1.4; 95% CI, 1.0-1.8; p = 0.03), syncope prior to pacemaker implant (HR, 1.8; 95% CI, 1.4-2.3; p < 0.001), previous myocardial infarction (HR, 1.5; 95% CI, 1.1-2.1; p = 0.03), heart failure (HR, 1.4; 95% CI, 1.0-1.9; p = 0.046), and high Charlson comorbidity index (HR, 1.6; 95% CI, 1.1-2.2; p = 0.01). Patients who experienced syncope post-pacemaker implant had higher mortality compared with patients who did not (adjusted HR, 1.6; 95% CI, 1.3-2.1; p < 0.001).


The authors concluded that syncope in paced patients with SSS is common, and is associated with higher mortality. Also, the predictors identified in this study suggest a multifactorial etiology of syncope.


According to the study, syncope with SSS is associated with increased mortality even if the patient has a pacemaker. Inclusion of patients ages 0-39 with SSS suggests that the study cohort included patients with structural heart disease. Unfortunately, the authors did not provide data on left ventricular function, which has a major impact on mortality risk.

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