Day-by-Day Blood Pressure Variability Is Associated With Neurological Functional Outcome After Acute Ischemic Stroke

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Day-by-Day Blood Pressure Variability Is Associated With Neurological Functional Outcome After Acute Ischemic Stroke

 

Changqiang Yang^1†, Kai Liu^1†, Yue Song², Shenzhen Gong¹, Runyu Ye¹, Zhipeng Zhang¹ and Xiaoping Chen^1*

• ¹West China Hospital, Sichuan University, Chengdu, China
• ²West China Second University Hospital, Sichuan University, Chengdu, China

Background: Increased blood pressure variability (BPV) might be a detrimental factor after acute ischemic stroke. Previous studies on the association between blood pressure variability in the acute ischemic stroke and functional outcome have yielded inconsistent results. We aimed to investigate the impact of day-by-day blood pressure variability within 7 days of onset on functional outcome at 3 months after acute ischemic stroke.

Methods: Total 367 patients hospitalized for ischemic stroke within 48 h of onset were enrolled. The acute stage of ischemic stroke was defined as the time period from symptom onset to 7 days. During this period, blood pressure was measured twice daily (respectively, in the morning during 8:00 a.m.−10:00 a.m., in the afternoon between 15:00 p.m. and 17:00 p.m.). Day-by-day blood pressure variability, including standard deviation (SD) and coefficient variation (CV) were derived and compared to functional outcome. We dichotomized function outcome according to mRS score and unfavorable outcome was defined as mRS ≥3.

Results: The patients with unfavorable outcome had significantly higher systolic BPV (within 7 days of onset) than those with favorable outcome (15.41 ± 4.59 vs. 13.42 ± 3.95 mmHg for SD, P < 0.001; 11.54 ± 3.23 vs. 10.41 ± 2.82 for CV, P = 0.001). Multivariable logistic regression analysis revealed that systolic BPV was significantly and independently associated with the 3-month functional outcome [odds ratio (OR) = 1.15, 95% confidence interval (CI): 1.07–1.22, P < 0.001 for SD; OR = 1.15, 95% CI: 1.06–1.26, P = 0.001 for CV]. In addition, After adjustment for multiple confounding factors, including age, gender, risk factors, stroke features, baseline severity, recanalized therapy, hemorrhagic transformation, pulmonary infection, white blood cell, estimated Glomerular Filtration Rate and mean BP, day-by-day BP variability was significantly correlated with an unfavorable outcome in the top vs. bottom quartile of systolic BPV (OR = 3.33, 95% CI: 1.41–7.85, P = 0.006 for SD; OR = 2.27, 95% CI: 1.04–4.94, P = 0.037 for CV) during 3-month follow-up. Similar trends were also observed for diastolic BPV. More importantly, incorporating SD of systolic BP into the conventional prediction model could significantly increase the AUC for prediction of 3-month unfavorable outcome after acute ischemic stroke (0.84 vs. 0.86; P = 0.0416).

Conclusions: Increased day-by-day blood pressure variability of systolic or diastolic BP in the acute ischemic stroke was associated with higher risk for unfavorable outcome at 3 months independent of blood pressure levels. Combining SD of systolic BP with conventional risk factors could improve the prediction of unfavorable outcome.

Introduction

Hypertension is the most prevalent modifiable risk factor for ischemic stroke and blood pressure reduction is an important goal for stroke risk reduction (1). Optimal blood pressure levels have been well-established for the primary and secondary prevention of ischemic stroke occurrence and recurrence (2). However, the optimal management of blood pressure during the acute stage of ischemic stroke has not been confirmed and remains controversial (3). A series of randomized clinical trials of blood pressure lowering in acute ischemic stroke have been conducted and showed a neutral effect of BP reduction on clinical outcomes (4–8). Recent studies have suggested that the risk of cardiovascular complications may not only depend on the magnitude of blood pressure elevation but also on the presence of increased blood pressure variability, even to a larger extent than average BP values in populations at high cardiovascular risk (9). Therefore, blood pressure variability may be an important predictor of ischemic stroke risk and outcome.

Available evidence about the effect of BPV on outcome after acute ischemic stroke is scarce. Most studies focus on the association between short-term blood pressure variability (BPV) within first 24–72 h after ischemic stroke onset and functional outcome (10–15). Some report that short-term BPV is associated with unfavorable outcome at 3 months after acute ischemic stroke (12–14), whereas others do not find any association (10, 11, 15). A recent systemic review and meta-analysis suggests that this short-term blood pressure variability assessed in the acute stage of ischemic stroke is associated with poor long-term functional outcome (16). However, there are limited data regarding the relationship between mid-term blood pressure variability (day-by-day BPV) and outcome in acute ischemic stroke. The aim of the present study is to investigate whether day-by-day blood pressure variability within 7 days of onset is associated with 3-month functional outcome of patients with acute ischemic stroke.