Blood Pressure

Impaired perfusion modifies the relationship between blood pressure and stroke risk in major cerebral artery disease

Authors: Yamauchi H, Higashi T, Kagawa S, Kishibe Y, Takahashi M.

OBJECTIVE: Blood pressure (BP) lowering may increase stroke risk in patients with symptomatic major cerebral artery disease and impaired perfusion. To investigate the relationships among BP, impaired perfusion and stroke risk.
METHODS: We retrospectively analysed data from 130 non-disabled, medically treated patients with either symptomatic extracranial carotid occlusion or intracranial stenosis or occlusion of the carotid artery or middle cerebral arteries. All patients had baseline haemodynamic measurements with 15O-gas positron emission tomography and were followed for 2 years or until stroke recurrence or death.
RESULTS: There was a negative linear relationship between systolic BP (SBP) and risk of stroke in the territory of the diseased artery. The 2-year incidence of ischaemic stroke in the territory in patients with normal SBP (<130 mm Hg, 5/32 patients) was significantly higher than in patients with high SBP (2/98, p<0.005). Multivariate analysis revealed that normal SBP and impaired perfusion were independently associated with increased risk of stroke in the previously affected territory, while risk of stroke elsewhere was positively correlated with SBP. Overall, high total stroke risk was observed at lower BP in patients with impaired perfusion and at higher BPs in patients without (interaction, p<0.01). Overall, the relationship between SBP and total stroke recurrence was J-shaped.
CONCLUSIONS: Impaired perfusion modified the relationship between blood pressure and stroke risk, although this study had limitations including the retrospective analysis, the potentially biased sample, the small number of critical events and the fact that BP was measured only as a snapshot in clinic.

Interarm blood pressure difference and mortality in patients with acute ischemic stroke

Authors: Kim J, Song TJ, Song D, Lee HS, Nam CM, Nam HS, Kim YD, Heo JH.

OBJECTIVE: The objective of this study was to assess the prognostic value of interarm difference of blood pressure (IAD) measured in acute ischemic stroke and to investigate its association with systemic atherosclerosis.
METHODS: This was a hospital-based retrospective observational study. Survival data and systolic/diastolic IAD were collected in patients with acute ischemic stroke. Systemic atherosclerosis was determined based on coronary CT angiography, transesophageal echocardiography, ankle-brachial index examination, and cerebral angiography covering both intracranial and extracranial cerebral arteries.
RESULTS: Of 834 patients, 10.3% had a systolic IAD ≥10 mm Hg, and 6.0% had a diastolic IAD ≥10 mm Hg. During a mean follow-up period of 2.96 ± 0.95 years, 92 patients died (including 68 cardiovascular deaths). In multivariate Cox regression adjusted for cardiovascular risk factors and initial stroke severity, the presence of systolic IAD ≥10 mm Hg was associated with increased risk of all-cause mortality (hazard ratio 1.97, 95% confidence interval 1.16-3.35) and cardiovascular mortality (HR 2.49, 95% CI 1.39-4.46). Patients with diastolic IAD ≥10 mm Hg also had increased risk of all-cause mortality (HR 3.43, 95% CI 1.94-6.08) and cardiovascular mortality (HR 3.51, 95% CI 1.83-6.74). The presence of systolic or diastolic IAD ≥10 mm Hg was associated with peripheral artery disease in the lower limbs, but not with atherosclerosis in the cerebral artery, coronary artery, or the aorta.
CONCLUSIONS: The presence of interarm systolic or diastolic blood pressure difference ≥10 mm Hg is a strong independent prognostic marker in acute ischemic stroke.

Blood pressure lowering in acute phase of stroke: latest evidence and clinical implications

Authors: Patarroyo SX, Anderson C.

Persistent controversy exists as to whether there are worthwhile beneficial effects of early, rapid lowering of elevated blood pressure (BP) in acute stroke. Elevated BP or 'hypertension' (i.e. systolic >140 mmHg) is common in stroke, especially in patients with pre-existing hypertension and large strokes, due to variable 'autonomic stress' and raised intracranial pressure. While positive associations between BP levels and poor outcomes are evident across a range of studies, very low BP levels and large reductions in BP have also been shown to predict death and dependence, more so for ischaemic stroke (IS) than intracerebral haemorrhage (ICH). Accumulating evidence indicates that early BP lowering can reduce haematoma expansion in ICH, but there is uncertainty over whether this translates into improved clinical outcomes, particularly since such an effect was not evident from haemostatic therapy in clinical trials. Guidelines generally recommend control of high systolic BP (>180 mmHg), but recent evidence indicates that even more modest elevation (>140 mmHg) increases risks of cerebral oedema and haemorrhagic transformation following thrombolysis in IS. Thus, any potential benefits of rapid BP lowering in acute stroke, particularly in IS, must be balanced against the potential risks of worsening cerebral ischaemia from altered autoregulation/perfusion. This paper explores current knowledge regarding the management of hypertension in acute stroke and introduces ongoing clinical trials aimed at resolving such a critical issue in the care of patients with acute stroke.

Home Blood Pressure Level, Blood Pressure Variability, Smoking, and Stroke Risk in Japanese Men: The Ohasama Study

Authors: Hashimoto T, Kikuya M, Ohkubo T, Satoh M, Metoki H, Inoue R, Asayama K, Kanno A, Obara T, Hirose T, Hara A, Hoshi H, Totsune K, Satoh H, Sato H, Imai Y.

BackgroundHypertension and smoking independently contribute to the risk of stroke. Our objective was to investigate home blood pressure (HBP) levels, day-by-day BP variability, and smoking in the prediction of stroke in Japanese men.MethodsIn this study, 902 men (mean age, 58.6 years) without a past history of stroke were evaluated. HBP was measured once every morning for 4 weeks. Day-by-day BP variability was defined as within-subject standard deviations (SD) of HBP. Smoking history was obtained from a standardized questionnaire. Hazard ratios (HRs) for stroke were examined by Cox regression model, with adjustment for possible confounders.ResultsDuring 13.1 years (median) of follow-up, 89 cerebral infarctions, 28 intracranial hemorrhages, and six other strokes occurred. Systolic HBP levels (HR = 1.59 per 14.6 mm Hg increase, P < 0.0001) and variability (HR = 1.26 per 3.1 mm Hg increase, P = 0.03) of +1 between-subject SD were significantly associated with cerebral infarction. The relationship between HBP and cerebral infarction differed with smoking status (interaction P = 0.021 and 0.017 for systolic level and variability, respectively). In analyses stratified according to smoking, systolic level (HR = 1.78, P < 0.0001) and variability (HR = 1.38, P = 0.006) were significantly associated with cerebral infarction in ever smokers (N = 511), but not in never smokers (N = 391; P ≥ 0.6 for both). No significant association was found between smoking and the risk of intracranial hemorrhage.ConclusionsIn ever smokers, both HBP levels and variability are significantly associated with the risk of cerebral infarction. Our findings further validate the benefit of smoking cessation in preventing cardiovascular disease (CVD), especially cerebral infarction.American Journal of Hypertension 2012; doi:10.1038/ajh.2012.62.

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