title: Effects of β-blocker selectivity on blood pressure variability and stroke: a systematic review.
abstract: OBJECTIVE
  β-Blockers increase variability in systolic blood pressure (SBP), which probably explains their lesser effectiveness in preventing stroke vs myocardial infarction compared with other agents. This increase in variability in blood pressure (BP) may be particularly marked on non-cardioselective agents, potentially calling into question the widespread first-line use of propranolol in migraine with aura, elderly patients with essential tremor or anxiety, and other groups at risk of stroke.
  
  
  METHODS
  We determined β-blocker subclass effects on variability in BP and stroke risk in a systematic review of randomized controlled trials (RCTs) comparing different types of β-blocker with placebo or other agents. We determined pooled estimates of the effect of treatment on group variability in BP (ratio of the variances [VR]) and on the risk of stroke vs myocardial infarction during follow-up.
  
  
  RESULTS
  Compared with other antihypertensives, variability in SBP was increased more by nonselective β-blockers (VR=1.34, 1.13-1.59, p =0.002, 25 comparisons, 9,992 patients) than by β1-selective agents (VR=1.09, 95% confidence interval 1.00-1.19, p =0.053, 68 comparisons, 40,746 patients; difference-p =0.038). In direct comparisons, variability in SBP was also significantly lower with β1-selective vs nonselective β-blockers (VR=0.81, 0.68-0.97, p =0.03, 18 comparisons, 954 patients). In comparisons with other antihypertensives, the increase in stroke risk with nonselective β-blockers ([OR]=2.29, 1.32-3.96, p =0.002) was more marked than with β1-selective agents (OR=1.24, 1.08-1.42, p =0.003, difference-p =0.03), as was the risk of stroke relative to the risk of myocardial infarction: OR=1.50 (0.93-2.42) vs 0.99 (0.82-1.19).
  
  
  CONCLUSIONS
  Use of β1-selective rather than nonselective agents may be advisable when β-blockers are indicated for patients at risk of stroke.
authors.affiliation: Stroke Prevention Research Unit, Department of Clinical Neurology, University of Oxford, Oxford, UK.
authors.forename: Alastair John Stewart
authors.initials: AJ
authors.lastname: Webb
authors.forename: Urs
authors.initials: U
authors.lastname: Fischer
authors.forename: Peter Malcolm
authors.initials: PM
authors.lastname: Rothwell
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects*; D016208:Databases, Factual / Q000706:statistics & numerical data; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000209:etiology*; D012189:Retrospective Studies; D020521:Stroke / Q000150:complications*
chemical_list: D000319:Adrenergic beta-Antagonists