Which parameters of beat-to-beat blood pressure and variability best predict early outcome after acute ischemic stroke?

Background and Purpose-In hypertensive populations, increasing blood pressu re (BP) levels and BP variability (BPV) are associated with a greater incid ence of target organ damage. After stroke, elevated 24-hour BP levels predi ct a poor outcome, although it is uncertain whether shorter-length BP recor dings assessing mean BP levels and BPV have a similar predictive role. The objectives of this study were to compare the different measures of beat-to- beat BP and BPV on outcome after acute ischemic stroke and assess whether t hese parameters were affected by stroke subtype. Methods-Ninety-two consecutive admissions with a CT-confirmed diagnosis of acute ischemic stroke were recruited, of whom 54 had cortical infarction, 2 9 subcortical, and 9 posterior circulation infarction. Casual and two 5-min ute recordings of beat-to-beat BP (Finapres, Ohmeda) were made under standa rdized conditions within 72 hours of ictus, with mean BP levels taken as th e average of this 10-minute recording and BPV as the standard deviation. Ou tcome was assessed at 30 days as dead/dependent or independent (Rankin less than or equal to 2). The effects of BP, BPV, and stroke subtype on outcome were studied with the use of logistic regression. Stroke subjects were sub sequently divided by BP quartiles and within each quartile into low- and hi gh-variability groups; the influence of high BPV on outcome was also assess ed. Results-The odds ratio for death/dependency was significantly higher in cor tical strokes compared with subcortical and posterior circulation strokes e ven after controlling for differences in BP and BPV (OR 4.19, P=0.002). Bea t-to-beat systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure (MAP +/- SD) levels were higher in the dead/dependent group compared with the independent group (MAP 106+/-20.4 mm Hg vs 97+/-19.1 mm Hg, P<0.02), as was MAP variability: 6.1 (interquartile range 4.5 to 7.4 mm Hg) versus 4.9 (3.8 to 6.4 mm Hg, P=0.02). The odds ratio for a poor outcome was 1.38 (P= 0.014) for every 10-mm Hg increase in MAP and 1.32 (P=0.02) for every l-mm Hg increase in MAP variability. Casual BP measurements had no prognostic si gnificance. For the group as a whole when separated into BP quartiles, thos e with a high MAP and DBP but not SEP variability within each quartile had a worse prognosis compared with those with a low BPV. Conclusions-A poor outcome at 30 days after ischemic stroke was dependent o n stroke subtype, beat-to-beat DBP, and MAP levels and variability. Importa nt prognostic information can be readily obtained from a short period of no ninvasive BP monitoring in the acute stroke patient. These findings have im portant implications, particularly regarding the use of hypotensive agents in the acute stroke period.