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Diurnal blood pressure change varies with stroke subtype in the acute phase
S L Dawson1, S N Evans, B N Manktelow
1University Department of Medicine for the Elderly, the Glenfield Hospital, Leicester, UK.
Background And Purpose:
It is unclear whether acute stroke is associated with a loss of the normal diurnal blood pressure (BP) change and whether stroke type influences this. Some of this confusion results from the use of fixed time definitions of day and night, which can be overcome by the use of cumulative sums analysis (cusums).
Methods:
Ninety-eight stroke patients had 24-hour BP monitoring (Spacelabs 90207) performed within 48 hours of ictus. Three subgroups were identified: cortical infarct, n=50; subcortical infarct, n=29; and primary intracerebral hemorrhage [PICH], n= 19. An age-matched control group of 74 subjects was also studied. Diurnal change was assessed by both day-night differences (absolute and percentage) and cusums (cusums plot height [CPH] and circadian alteration magnitude [CDCAM]); ANCOVA was used to compare groups.
Results:
Compared with control subjects, cortical infarct and PICH subgroups had significantly reduced mean diurnal systolic changes using day-night differences (absolute, -12 and -17 mm Hg; percentage, -10 and -12, respectively; P < 0.0001) and cusums (CDCAM, -6.96 and -8.6 mm Hg; CPH, -32.05 and -46.04 mm Hg, respectively; P < 0.005), only the subcortical infarct subgroup demonstrated reduced percentage differences (-4.4%, P < 0.02). Mean diastolic differences were significantly reduced in all stroke subgroups(CPH, -24.84, -17.31, and -36.92 mm Hg; absolute, -8.26, -4.04, and -11.44 mm Hg; percentage, -10.65, -5.81, and -15.23%, for cortical infarct, subcortical infarct, and PICH subgroups, respectively; P < 0.05), except for CDCAM, which was not reduced in subcortical infarcts (-4.78 and -7.70 mm Hg for cortical infarct and PICH subgroups, respectively; P < 0.001).
Conclusions:
Diurnal BP change was reduced in the 3 stroke subgroups studied, especially in patients with cortical infarcts and PICH. This may reflect damage to the central modulation of autonomic BP control. The implications in terms of prognosis and therapy in the acute period require further study.