Impact of initial blood pressure on antihypertensive response in patients with acute hypertension
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Serafin Farias1, W Frank Peacock1, Michael Gonzalez1
1Emergency Medicine, Baylor College of Medicine, Houston, TX.
Insights
Higher initial blood pressure (BP) does not hinder achieving target BP within 30 minutes with intravenous nicardipine or labetalol. The study found initial BP is not a predictor for reaching the specified BP target range.
Area of Science:
- Emergency Medicine
- Pharmacology
- Cardiovascular Research
Background:
- Limited data exist on the interaction between hemodynamic response and presenting blood pressure (BP) in patients receiving antihypertensive agents.
- Existing research primarily focuses on the effect profiles of different antihypertensive drugs.
Purpose of the Study:
- To investigate whether higher initial systolic blood pressure (SBP) affects the likelihood of achieving a target BP range within 30 minutes.
- To evaluate the predictive value of presenting BP on treatment outcomes in the emergency department.
Main Methods:
- A substudy of the CLUE trial involving 223 patients randomized to intravenous nicardipine or labetalol.
- Patients received FDA-recommended dosing to reach a predefined SBP target range (±20 mm Hg) within 30 minutes.
- Logistic regression modeled the likelihood of achieving target SBP, considering initial BP as a categorical variable.
Main Results:
- No significant difference in achieving the target SBP range was observed between patients with higher (median 218 mm Hg) and lower (median 190 mm Hg) initial SBP.
- The proportion of patients achieving target SBP at 30 minutes was similar (85.2% vs 88.9%, P = 0.42).
- Randomization to nicardipine, but not initial SBP, was associated with achieving the target SBP.
Conclusions:
- Presenting systolic blood pressure is not a predictor of achieving a prespecified target SBP range within 30 minutes.
- Intravenous nicardipine and labetalol are effective in managing acute hypertension regardless of initial BP severity.
Introduction:
The effect profile of differing antihypertensive agents is well studied, but minimal data regarding the interaction between hemodynamic response and presenting blood pressure (BP) exist.
Hypothesis:
Achievement of target BP is less likely in patients with higher initial BPs.
Methods:
This is a substudy of the multicenter safety and efficacy Evaluation of intravenous Cardene (nicardipine) and Labetalol Use in the Emergency department (CLUE) trial that randomized patients to Food and Drug Administration-recommended intravenous dosing of nicardipine or labetalol to reach a physician predefined systolic BP (SBP) and target range (TR) of ±20 mm Hg within 30 minutes. The proportion achieving TR was assessed as a function of initial SBP, and dichotomized comparisons were made using median SBP. Likelihood of a final BP within TR was modeled using logistic regression with forced inclusion of initial BP as a categorical variable.
Results:
A total 223 patients were enrolled; 115 (51.6%) had an initial SBP greater than the median 202 mm Hg. The median SBP (interquartile range) of the high BP group was 218 (210-228) mm Hg vs the low BP group 190 (182-197) mm Hg (P < 0.0001). No groupwise differences existed except that the high group had higher mean (SD) serum creatinine level at baseline (3.1 [3.9] vs 1.9 [2.3], P = .008). The proportion of patients achieving SBP within TR at 30 minutes did not differ (85.2% [98 of 115] vs 88.9% [96 of 108], P = .42). Randomization to nicardipine (odds ratio = 2.85; 95% confidence interval, 1.16-7.01), but not initial SBP (odds ratio = 0.60; 95% confidence interval, 0.25-1.44), was associated with achievement of target SBP at 30 minutes.
Conclusion:
Initial SBP is not a predictor of the ability to achieve a prespecified target range SBP within 30 minutes.
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