Impact of Stroke Subtype on Blood Pressure Course During the Acute Stage of Cerebral Ischemia
To the Editor:
We read with interest the recent article by Toyoda and colleagues investigating the acute blood pressure (BP) course using consecutive manual BP recordings among patients with different ischemic stroke (IS) subtypes and determining which baseline factors contribute to BP changes during the acute stroke stage.1 The authors concluded that during the first 6 days of hospitalization the BP course varied widely according to stroke subtypes with lacunar and atherothrombotic patients having higher BP values than the other ischemic stroke subtypes. They also reported that pre-existing hypertension and poorly controlled diabetes mellitus were associated with the acute systolic and diastolic BP (SBP and DBP) courses.
Our group has previously investigated the early spontaneous time course of BP in IS subtypes of different etiology as well as the factors influencing acute BP changes during the first 24 hours of cerebral ischemia by means of 24-hour BP monitoring.2,3 Similarly to Toyoda et al, we reported higher admission BP levels in patients with lacunar infarction and documented that early BP course (between 3 and 27 hours from symptom) varied depending on stroke subtype. More specifically, SBP dropped sharply in the atherothrombotic (10.1%) and lacunar group (10.4%), whereas a milder drop was documented in patients with cardioembolic stroke (3.3%) and infarct of undetermined cause (5.5%). Pre-existing hypertension and increasing stroke severity were associated with higher 24-hour BP values, whereas congestive heart failure and coronary heart disease correlated to lower 24-hour levels.
In view of the partly deviant observations between the former studies in terms of the baseline factors that determine acute BP changes, certain methodological issues of the study of Toyoda et al are worth pondering. For one, although BP course has been shown to be highly variable during even the first minutes of cerebral ischemia,4 the elapsed time between symptom onset to hospital admission was not included as a potential confounder in the analyses. Second, congestive heart failure and early hypodensity in admission brain CT scan have been related to lower and higher BP levels respectively during the acute stroke stage in white population.3,5 However, the impact of the former 2 factors on BP course was not investigated in the Japanese study. Third and most important, the rates of use of intravenous or per oral antihypertensive agents were different among the stroke subtypes in the study of Toyoda and colleagues. However, antihypertensive treatment during the acute stroke stage has been previously associated with larger or extreme BP reductions and may influence substantially the spontaneous BP course.6,7 Because the authors did not control for the use of BP-lowering medications, the differences documented in BP courses between the IS subgroups should be interpreted with caution.
In conclusion, the findings of our group and Toyoda et al draw attention to the differences in the early BP course of stroke subtypes of different etiology and provide useful data regarding the pre-existing factors that may influence acute BP changes in IS patients. Should these observations be verified in the ongoing clinical trials (COSSACS, CHIPPS, ENOS), stroke subtype should be taken into consideration in the management of acute poststroke hypertension.
Toyoda K, Okada Y, Fujimoto S, Hagiwara N, Nakachi K, Kitazono T, Ibayashi S, Iida M. Blood pressure changes during the initial week after different subtypes of ischemic stroke. Stroke. 2006; 37: 2637–2639.
Tsivgoulis G, Spengos K, Vemmos KN, Castillo J, Davalos A. Blood pressure in acute stroke and its prognostic value. Response. Stroke. 2004; 35: 1786–1787.
Castillo J, Leira R, Garcia MM, Serena J, Blanco M, Davalos A. Blood pressure decrease during the acute phase of ischemic stroke is associated with brain injury and poor stroke outcome. Stroke. 2004; 35: 520–526.
Oliveira-Filho J, Silva SC, Trabuco CC, Pedreira BB, Sousa EU, Bacellar A. Detrimental effect of blood pressure reduction in the first 24 hours of acute stroke onset. Neurology. 2003; 61: 1047–1051.