Age-Dependent Effect of Beta Blockers in Preventing Vasovagal Syncope.
Circ Arrhythm Electrophysiol. 2012 Sep 12;
Authors: Sheldon RS, Morillo CA, Klingenheben T, Krahn AD, Sheldon A, Rose MS
BACKGROUND: -Beta-blockers have little effectiveness in preventing vasovagal syncope in unselected populations, but they might be effective in older patients. We determined whether beta-blockers prevent vasovagal syncope in an age-related fashion. METHODS AND RESULTS: -Two populations were studied. A proportional hazards analysis was performed on an observational cohort study of 153 patients with vasovagal syncope, 52 of whom received beta-blockers. A multivariable proportional hazards model stratified by center was performed on 208 participants in the randomized Prevention of Syncope Trial (POST), examining the interaction between age group and treatment with metoprolol. Age-specific hazard ratios were estimated for both studies, and combined using the inverse variance meta-analytic method. In the cohort study the hazard ratio for syncope if treated with beta-blockers was 1.54 (95% CI 0.78 to 3.05) for patients <42 years, and 0.48 (95% CI 0.12 to 1.92) for patients ?42years. In POST the proportional hazards model showed interactions between age and treatment effect (p = 0.026). The hazard ratio for patients ?42 years who received metoprolol was 0.53 (95% CI 0.25 to 1.10); in patients <42 years, the hazard ratio was 1.62 (95% CI 0.85 to 3.10). A pooled analysis of both studies yielded an estimate of the hazard ratio for patients <42 years of 1.58 (CI 1.00-2.31) and the hazard ratio for patients ?42 years was 0.52 (CI 0.27-1.01). The two age groups differed significantly in response to beta-blockers (p = 0.007). CONCLUSIONS: -Beta-blocker treatment may suppress vasovagal syncope in middle-aged patients aged >42 years.
PMID: 22972872 [PubMed - as supplied by publisher]