Abstract
Background and Purpose
Severely elevated blood pressure (BP) and aggressive BP reduction are both associated with poor outcome in acute ischemic stroke (AIS). In non-tPA patients, the AHA recommends anti-hypertensive therapy only if BP is ≥220/120mmHg, with a goal of 15–25% reduction in the first 24hours. We hypothesized that AIS patients often receive anti-hypertensives in the emergency department (ED) below the recommended threshold, and that BP reduction is often greater than 20%.
Methods
In 2005, AIS cases were ascertained at all 16 hospitals in Greater Cincinnati. BP was recorded at ED presentation and before and after anti-hypertensive treatment. Hypertension was defined as BP ≥220/120mmHg. Chi square and Mann-Whitney U-tests were used for comparisons.
Results
1739 AIS patients met inclusion criteria. Median age was 72years, with 43% male and 25% black. Of 218 treated with anti-hypertensives, 65 (30.0%) met treatment criteria immediately prior to treatment. Treated patients were younger (66 vs. 73years, p<0.001) with greater stroke severity than untreated patients (NIHSS 4 vs. 3, p=0.028). Median change in systolic BP was -25mmHg (range −96 to 25). Median percentage change in systolic BP was −12.3% (range −49.2 to 16.1). Systolic BP decreased more than 20% in 52 treated patients (23.7%).
Conclusions
Only one-third of AIS patients treated with anti-hypertensives met AHA recommended treatment criteria, and the rate of change of BP was frequently greater than recommended. Further studies are warranted to determine the impact of practice patterns on AIS outcomes.
Keywords: Emergency Medicine, blood pressure, acute stroke, cerebral infarct
Introduction
Blood pressure (BP) elevation is common in acute ischemic stroke (AIS).1,2 Severely elevated systolic blood pressure (SBP) is associated with increased risk of neurologic decline and poor outcome in AIS.2 However, aggressively lowering SBP is also associated with neurologic decline and poor outcome.1 For every 10mmHg fall in SBP below 150mmHg there was a 17.9% increase in risk of death at 14 days.2 Thus, unwarranted BP reduction may be harmful in AIS.
American Heart Association (AHA) guidelines for the management of BP in AIS recommend anti-hypertensive therapy only if BP is greater than 220/120mmHg, with a goal of 15–25% BP reduction in the first 24hours.3 In this study, we assessed adherence by emergency physicians to the AHA BP treatment guidelines for AIS. We sought to describe practice patterns in BP management among treating Emergency Department (ED) physicians within our population. We hypothesized that AIS patients with BP below the recommended treatment threshold often receive anti-hypertensives in the ED, and that BP reduction greater than 20% occurs early in treated patients.
Methods
The Greater Cincinnati/Northern Kentucky (GCNK) Stroke Study is a population-based epidemiological study designed to measure incidence rates and temporal trends of stroke within a biracial population of the 1.3 million residents of the GCNK region (5 counties bordering the Ohio River).4 Although residents of nearby counties seek care at these hospitals, only residents of the 5 counties were included. The study period was January 1 to December 31, 2005. Detailed methods for case ascertainment and data collection have been previously described.4
For this analysis, cases were limited to AIS cases presenting to all 16 EDs in the region. Transient ischemic attacks were excluded. BP was recorded at ED presentation and before and after treatment with anti-hypertensives, if given. Cases were classified based on presenting BP as hypertensive (BP ≥220/120mmHg), hypotensive (SBP <100mmHg), or normotensive (neither hypotensive nor meeting AHA criteria for anti-hypertensive therapy).3 Cases who received rt-PA were excluded. For patients receiving anti-hypertensives, treatment was recorded up to a maximum of three doses and/or medications. Recorded BP immediately prior to and after each dose was abstracted and percent change of SBP with treatment was calculated. Chi square tests and Mann-Whitney U-tests were used for comparisons.
Results
There were 1739 cases of adult AIS patients presenting to local EDs included for this analysis. Median age of AIS cases was 72years; 43.4% were male, and 24.2% were black. Baseline demographics of treated vs. untreated cases are described in Table 1. A greater proportion of blacks were treated for hypertension (18.6% vs. 10.7%, p<0.001). Among those who met criteria for BP lowering, the proportion treated was not statistically different between blacks and whites (70% vs. 59.4%, p=0.370). Among those who did not meet criteria, significantly more blacks were treated than whites (13.5% vs. 8.3%, p=0.004). Treated cases were younger than untreated (66 vs. 73years, p<0.001), and treated cases had greater stroke severity than untreated (NIHSS 4 vs. 3, p=0.028).
Table 1.
Characteristics of patients treated and not treated with anti-hypertensives.
| Not treated, N = 1520 | Treated, N = 219 | p value | |
|---|---|---|---|
| Median age, years (range) | 73 (20–105) | 66 (38–94) | <0.001 |
| Female, N (%) | 863 (56.8) | 121 (55.3) | 0.663 |
| Black, N (%) | 341 (22.4) | 78 (35.6) | <0.001 |
| Median retrospective NIHSS (range) | 3 (0–40) | 4 (0–37) | 0.028 |
At presentation, 109 cases (6.3%) met AHA criteria for BP lowering, of which 69 (63.3%) received anti-hypertensive therapy. Forty cases (36.7%) met treatment criteria but were not treated. There were 219 cases treated with anti-hypertensives in the ED, of which 69 (31.5%) met treatment criteria on ED arrival and 65 (30.0%) met treatment criteria immediately prior to treatment. Table 2 compares BP on presentation in treated vs. not treated patients.
Table 2.
Blood pressure at Emergency Department presentation.
| Not treated N = 1520 |
Treated N = 219 |
p value | |
|---|---|---|---|
| Initial ED systolic BP, median (range) | 152 (66–267) | 198 (112–280) | <0.001 |
| Initial ED diastolic BP, median (range) | 81 (0–185) | 101 (51–183) | <0.001 |
| Hypotensive* at presentation, N (%) | 42 (2.8) | 0 (0.0) | |
| Normal BP at presentation, N (%) | 1431 (94.6) | 150 (68.5) | <0.001 |
| Hypertensive† at presentation, N (%) | 40 (2.6) | 69 (31.5) | |
Hypotension: SBP <100mmHg
Hypertension: BP ≥220/110mmHg
Table 3 shows response to treatment with anti-hypertensives. Median change in SBP for the 207 cases with measurements available before and after the first treatment was −25mmHg (range −96 to 25). The median percent change in SBP was −12.3% (range −49.2% to 16.1%). SBP decreased by more than 20mmHg in 115 treated cases (52.5%), and by more than 20% in 52 treated cases (23.7%). Three cases became hypotensive after treatment.
Table 3.
Effects of anti-hypertensive treatment. Data are medians (ranges) or frequencies (percents) as appropriate.
| Treated | |
|---|---|
| Pre-treatment median systolic BP (n=217) | 200 (118–264) |
| Pre-treatment median diastolic BP(n=217) | 103 (49–178) |
| Hypertensive* before treatment | 65/217 (30.0) |
| Hypotensive† post-treatment | 3/207 (1.4) |
| After 1st dose | 1/207 (0.5) |
| After 2nd dose | 0/89 (0.0) |
| After 3rd dose | 2/40 (5.1) |
| %change SBP after 1st anti-hypertensive (n=207) | −12.3 (−49.2 to 16.1) |
| %change SBP after 2nd anti-hypertensive (n=89) | −10.7 (−51.8 to 21.1) |
| %change SBP after 3rd anti-hypertensive (n=40) | −13.0 (−62.2 to 7.5) |
Hypertension: BP ≥220/110mmHg
Hypotension: SBP <100mmHg
Not all treated patients had BP measurements available before after treatment.
Discussion
This study of 16 hospitals, representing academic and community hospitals in both urban and suburban neighborhoods is the first to compare “real world” ED BP management with AHA recommendations. ED management of BP in AIS was not consistent with AHA guidelines. Anti-hypertensive therapy was often given despite not meeting treatment criteria, and the reduction in SBP was greater than 20% in one out of four treated cases. Interestingly, one in three cases who met AHA criteria for treatment did not receive anti-hypertensives.
Physicians may consider hypertension with AIS a form of hypertensive emergency. The treatment for hypertensive emergency, as in decompensated heart failure or aortic dissection, involves early aggressive BP reduction. Thus, aggressive management of BP in AIS seen in this study may be due to approaching AIS as hypertensive emergency. Our findings may indicate a need for additional education regarding BP management in AIS.
Importantly, the AHA guidelines for BP lowering in AIS are based on limited data. While there is an association between extremes in BP and worse outcome after AIS, few trials address the question of whether BP intervention improves outcome. Small randomized studies demonstrated a negative outcome effect after BP lowering.5,6 Other trials have been inconclusive.7 Recent trials of modest BP lowering have shown promise.8,9 Overall, due to conflicting data between small trials, definitive conclusions on early BP reduction after AIS cannot be made. Larger randomized controlled trials are needed and ongoing (ENOS trial).
Limitations of our study include its retrospective data collection, unknown pre-stroke baseline BP and inability to assess “relative” hypertension or hypotension for each patient, unknown indications for antihypertensive therapy, limited generalizability beyond our population, and unknown impact of BP management on patient outcomes.
Acknowledgments
Funding: NIH: R01NS030678, T32NS047996.
Footnotes
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Disclosures: None.
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