Treatment of post-stroke hypertension. A practical guide

Blood Pressure Management in Acute Stroke: Comparison of Current Guidelines with Prescribing Patterns

Objective:

Current recommendations for treating elevated blood pressure (BP) in the acute stroke are based largely on expert opinion and vary with regard to treatment thresholds and choice of antihypertensive agents. In this study we investigate the influence of these recommendations by comparing the management of hypertension in acute stroke at a tertiary care hospital with current guidelines.

Method:

Retrospective chart review of patients admitted with acute stroke at The Ottawa Hospital-General Campus over six consecutive months. The use of antihypertensive medications (type, dose, routes of administration, BP recordings) in the first seven days after admission was noted.

Results:

Transdermal nitroglycerin paste was the most commonly used antihypertensive agent. In contrast to the 15% reduction in BP over 24 hours recommended for lowering BP in hypertensive patients with ischemic stroke, nitroglycerin caused a >15% reduction of BPover the first 24 hours on 60% of the occasions used. Furthermore, despite concerns about sublingual nifedipine, this was the second most commonly prescribed agent. Surprisingly, the mean time to first BP measurement following initiation of antihypertensive therapy was 117 ± 43 minutes in ischemic stroke and 88 ± 89 minutes in hemorrhagic strokes.

Conclusions:

The current guidelines for management of acute poststroke hypertension appear to have little influence on prescribing patterns, leading to considerable variations in practice. Such variations, likely due to uncertainty caused by lack of evidence from randomised controlled trials, are intolerable as patients maybe submitted to nonstandardised, potentially harmful care such as inappropriate choice of antihypertensives and inadequate BP monitoring as observed in this study.

Hypertensive Emergencies in the Emergency Department

Hypertension affects approximately one-third of Americans. An additional 30% are unaware that they harbor the disease. Significantly increased blood pressure constitutes a hypertensive emergency that could lead to end-organ damage. When organs such as the brain, heart, or kidney are affected, an intervention that will lower the blood pressure in several hours is indicated. Several pharmacologic options are available for treatment, with intravenous antihypertensive therapy being the cornerstone, but there is no standard of care. Careful consideration of each patient's specific complaint, history, and physical examination guides the emergency physician through the treatment algorithm.

Current diagnosis and management of hypertensive emergency

The appropriate and timely evaluation and treatment of patients with severely elevated blood pressure is essential to avoid serious adverse outcomes. Most importantly, the distinction between a hypertensive emergency (crisis) and urgency needs to be made. A sudden elevation in systolic (SBP) and/or diastolic blood pressure (DBP) that is associated with acute end organ damage (cardiovascular, cerebrovascular, or renal) is defined as a hypertensive crisis or emergency. In contrast, acute elevation in SBP and/or DBP not associated with evidence of end organ damage is defined as hypertensive urgency. In patients with a hypertensive emergency, blood pressure control should be attained as expeditiously as possible with parenteral medications to prevent ongoing and potentially permanent end organ damage. In contrast, with hypertensive urgency, blood pressure control can be achieved with the use of oral medications within 24-48 hours. This paper reviews the management of hypertensive emergencies.

The diagnosis and management of hypertensive crises

Severe hypertension is a common clinical problem in the United States, encountered in various clinical settings. Although various terms have been applied to severe hypertension, such as hypertensive crises, emergencies, or urgencies, they are all characterized by acute elevations in BP that may be associated with end-organ damage (hypertensive crisis). The immediate reduction of BP is only required in patients with acute end-organ damage. Hypertension associated with cerebral infarction or intracerebral hemorrhage only rarely requires treatment. While nitroprusside is commonly used to treat severe hypertension, it is an extremely toxic drug that should only be used in rare circumstances. Furthermore, the short-acting calcium channel blocker nifedipine is associated with significant morbidity and should be avoided. Today, a wide range of pharmacologic alternatives are available to the practitioner to control severe hypertension. This article reviews some of the current concepts and common misconceptions in the management of patients with acutely elevated BP.

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 pressure (BP) levels and BP variability (BPV) are associated with a greater incidence of target organ damage. After stroke, elevated 24-hour BP levels predict a poor outcome, although it is uncertain whether shorter-length BP recordings 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 these 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, 29 subcortical, and 9 posterior circulation infarction. Casual and two 5-minute recordings of beat-to-beat BP (Finapres, Ohmeda) were made under standardized conditions within 72 hours of ictus, with mean BP levels taken as the average of this 10-minute recording and BPV as the standard deviation. Outcome was assessed at 30 days as dead/dependent or independent (Rankin </=2). The effects of BP, BPV, and stroke subtype on outcome were studied with the use of logistic regression. Stroke subjects were subsequently divided by BP quartiles and within each quartile into low- and high-variability groups; the influence of high BPV on outcome was also assessed.

RESULTS

The odds ratio for death/dependency was significantly higher in cortical strokes compared with subcortical and posterior circulation strokes even after controlling for differences in BP and BPV (OR 4.19, P=0.002). Beat-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 1-mm Hg increase in MAP variability. Casual BP measurements had no prognostic significance. For the group as a whole when separated into BP quartiles, those with a high MAP and DBP but not SBP 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 on stroke subtype, beat-to-beat DBP, and MAP levels and variability. Important prognostic information can be readily obtained from a short period of noninvasive BP monitoring in the acute stroke patient. These findings have important implications, particularly regarding the use of hypotensive agents in the acute stroke period.

Blood pressure exceeding national guidelines among women after stroke

BACKGROUND AND PURPOSE

After a transient ischemic attack or stroke, the risk for recurrence may be reduced by treatment of hypertension. The purpose of this study was to determine how commonly blood pressure exceeds national guidelines among patients who have had one of these events.

METHODS

Subjects were 644 women participating in a randomized trial of estrogen for secondary stroke prevention. We measured blood pressure 1 month after the stroke or TIA while patients were under the care of their personal physicians. Among 536 patients, a second measure was made at an average of 2.9 years after the first.

RESULTS

The mean age of participants was 71 years, and 73% reported a history of hypertension. At baseline, only 44% (280/644) of the women had blood pressure values within national guidelines (<140/90 mm Hg). With separate guidelines used for diabetics (<130/85 mm Hg) and nondiabetics (<140/90 mm Hg), the proportions of women within the guidelines were 27% and 44%, respectively. Overall, 39% of patients were within the diabetes-adjusted guidelines. Among patients whose blood pressure exceeded 140/90 mm Hg at first examination, 55% were still in excess at follow-up. Features associated with severe hypertension at first examination (>160/100 mm Hg) were history of hypertension, education less than college, and higher cognitive functioning.

CONCLUSIONS

Blood pressure values in excess of national guidelines are common after stroke and TIA, especially among diabetic patients. Efforts to lower blood pressure control may enhance secondary prevention.