Does the normal daily blood-pressure rhythm differ depending on the type of stroke?

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The study asked whether acute stroke is associated with a loss of normal daily blood-pressure (BP) variation, and whether that association differs by stroke type. The researchers noted that defining day and night by fixed clock times contributes to uncertainty, an issue that cumulative sums analysis (cusums) can overcome.

In this observational comparison, 98 stroke patients underwent 24-hour BP monitoring with the Spacelabs 90207 within 48 hours of stroke onset. There were three subgroups: cortical infarct, 50 patients; subcortical infarct, 29; and primary intracerebral hemorrhage (PICH), 19. An age-matched control group of 74 subjects was also studied.

Daily variation was assessed using both absolute and percentage day–night differences and cusums measures: cusums plot height (CPH) and circadian alteration magnitude (CDCAM). Analysis of covariance (ANCOVA) was used to compare groups.

Compared with controls, the cortical infarct and PICH groups had significantly smaller mean daily systolic BP changes. For cortical infarct and PICH, respectively, the reported differences from controls were −12 and −17 mm Hg for absolute day–night differences, and −10 and −12 for percentage differences (P < 0.0001). Cusums also showed reductions: CDCAM differences were −6.96 and −8.6 mm Hg, and CPH differences were −32.05 and −46.04 mm Hg, respectively (P < 0.005). In the subcortical infarct group, a reduction in systolic variation was found only for the percentage day–night difference (−4.4%, P < 0.02).

Mean diastolic variation was significantly reduced in all three stroke groups on CPH and on absolute and percentage day–night differences. In the order cortical infarct, subcortical infarct, and PICH, differences from controls were −24.84, −17.31, and −36.92 mm Hg for CPH; −8.26, −4.04, and −11.44 mm Hg for absolute day–night differences; and −10.65, −5.81, and −15.23% for percentage differences (P < 0.05). CDCAM was the exception: it was not reduced in subcortical infarct, while the differences for cortical infarct and PICH were −4.78 and −7.70 mm Hg, respectively (P < 0.001).

The researchers concluded that daily BP variation was reduced in all three stroke subgroups studied, especially in cortical infarct and PICH. They suggested this may reflect damage to the central modulation of autonomic BP control. The implications for prognosis and treatment during the acute period require further study.