Age-Dependent Effect of β-Blockers in Preventing Vasovagal Syncope

Abstract

Background-β-blockers have little effectiveness in preventing vasovagal syncope in unselected populations, but they might be effective in older patients. We determined whether β-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 β-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 β-blockers was 1.54 (95% CI, 0.78-3.05) for patients aged <42 years and 0.48 (95% CI, 0.12-1.92) for patients aged ≥42 years. In POST, the proportional hazards model showed interactions between age and treatment effect (P=0.026). The hazard ratio for patients aged ≥42 years who received metoprolol was 0.53 (95% CI, 0.25-1.10); in patients aged <42 years, the hazard ratio was 1.62 (95% CI, 0.85-3.10). A pooled analysis of both studies yielded an estimate of the hazard ratio of 1.58 (CI, 1.00-2.31) for patients aged <42 years, and the hazard ratio was 0.52 (CI, 0.27-1.01) for patients aged ≥42 years. The 2 age groups differed significantly in response to β-blockers (P=0.007). Conclusions-β-blocker

Syncope

“…A recent meta-analysis demonstrated a statistically significant difference in response in those aged <42 years and ≥42 years (test of interaction P=0.007). 86 β-Blocker use reduced syncope recurrence in those aged ≥42 years by 48% but increased the risk in those aged < 42years by 58%. 86 Accordingly, the cautious use of β-blockers is reasonable in older patients with vasovagal syncope, particularly when hypertension in present.…”

Syncope in the Older Person

“…A multicenter randomized controlled study of metoprolol showed no benefit overall, but suggested benefit in patients older than 42 years. 57,58 This theory will be the subject of a further randomized trial of metoprolol in this age group (POST 5 [Prevention of Syncope Trial 5], RS Sheldon, personal communication, June 2013). Fludrocortisone is commonly used in VVS management, but there have been no published randomized data in adults, although the POST II study 59 in abstract form suggests that there may no benefit at all (http://www.theheart.…”

Does any therapy really work for neurocardiogenic syncope?

“…No difference was observed in recurrence of syncope, even when stratified by age and isoproterenol response during tilt test. Subsequent pooled analysis with non-randomized patients found a significant interaction of beta-blockers with age, suggesting benefit after age 42, and potential harm in younger patients [8].…”