Blood pressure variability and stroke: A risk marker of outcome and target for intervention

Relationship of Day-by-Day Blood Pressure Variability and Admission Stroke Severity in Acute Ischemic Stroke

OBJECTIVES

Research on the association between stroke severity and day-by-day blood pressure variability (BPV) in acute ischemic stroke (AIS) is rare as the majority focus on the blood pressure (BP) or the short-term BPV. Our study aims to explore the exact roles of daily BPV through the 7-day commencement on stroke severity in AIS.

METHODS

The study included 633 patients with AIS, defining AIS as the time from the beginning of symptom up to 7 days with recording BP twice a day as well as calculating the daily BPV, and then matching them to the stroke severity. The logistic regression models were used to evaluate associations between stroke severity and day-by-day BPV. We used the smooth curve fitting to identify whether there was a nonlinear association. In addition, the subgroup analyses were performed using the logistic regression.

RESULTS

According to the modified National Institutes of Health Stroke Scale score, 301 (47.5%) patients were allocated to the mild stroke group and 332 (52.5%) to the moderate-to-severe stroke group. In terms of stroke categories, we found no significant difference between BP at admission or mean BP. However, the moderate-to-severe stroke group exhibited higher daily BPV. The multiple logistic regression analysis indicated that day-by-day BPV was positively correlated to stroke severity [odds ratio (OR)=1.05, 95% CI:1.01-1.1, P =0.03 for SBP-SD; OR=1.08, 95% CI:1.01-1.15, P =0.03 for SBP-CV; OR=1.04, 95% CI:1.01-1.07, P =0.015 for SBP-SV).

CONCLUSIONS

High day-by-day BPV in AIS was associated with more severe stroke independent of BP levels.

Dysautonomia and activity in the early stroke recovery period

Maintaining cerebral perfusion in the early stages of recovery after stroke is paramount. Autoregulatory function may be impaired during this period leaving cerebral perfusion directly reliant on intravascular volume and blood pressure (BP) with increased risk for expanding cerebral infarction during periods of low BP and hemorrhagic transformation during BP elevations. We suspected that dysautonomia is common during the acute period related to both pre-existing vascular risk factors and potentially independent of such conditions. Thus, we sought to understand the state of the science specific to dysautonomia and acute stroke. The scoping review search included multiple databases and key terms related to acute stroke and dysautonomia. The team employed a rigorous review process to identify, evaluate, and summarize relevant literature. We additionally summarized common clinical approaches used to detect dysautonomia at the bedside. The purpose of this scoping review is to understand the state of the science for the identification, treatment, and impact of dysautonomia on acute stroke patient outcomes. There is a high prevalence of dysautonomia among persons with stroke, though there is significant variability in the type of measures and definitions used to diagnose dysautonomia. While dysautonomia appears to be associated with poor functional outcome and post-stroke complications, there is a paucity of high-quality evidence, and generalizability is limited by heterogenous approaches to these studies. There is a need to establish common definitions, standard measurement tools, and a roadmap for incorporating these measures into clinical practice so that larger studies can be conducted.

Daily blood pressure variability in relation to neurological functional outcomes after acute ischemic stroke

Background

Prior research has shown inconclusive findings regarding the relationship between blood pressure variability (BPV) in acute ischemic stroke (AIS) and functional outcomes. Most research has examined the connection between short-term BPV during the early 24-72 h after the occurrence of ischemic stroke and functional prognosis. We sought to determine the relationship between daily BPV at 7 days of commencement and functional outcomes during the 3 months following AIS.

Methods

Altogether, 633 patients with AIS admitted within 72 h of commencement were enrolled. AIS was defined as the time from the onset of symptoms to 7 days. Throughout this period, blood pressure (BP) was recorded twice daily (casual BP cuffs). The daily BPV, with standard deviation (SD) and coefficient of variation (CV), was calculated and matched to the functional results. The adverse outcome was characterized as a modified Rankin scale (mRS)≥3, which comprised the recurrence of stroke, clinical intracranial bleeding, and death.

Results

In total, 633 participants were included, and the incidence of adverse outcomes was 14.06% (89/633). There was a significant positive correlation between daily BPV and adverse outcomes but not between mean BP and risk. Smooth curve fitting revealed a U-shaped connection between the mean BP and adverse clinical outcomes. Multivariable logistic regression analysis showed an independent correlation between daily BPV and an adverse outcome in the top vs. bottom quartile of systolic BPV (odds ratio [OR] = 2.4, 95% confidence interval [CI]: 1.17-4.96, P = 0.018 for SD; OR = 2.4, 95% CI: 1.17-4.93, P = 0.017 for CV) during a 3-month follow-up period. Identical results have been reported for diastolic BPV.

Conclusion

Irrespective of BP level, elevated daily systolic BPV and diastolic BPV in AIS were associated with an increased risk of adverse outcomes within 3 months. We also discovered a U-shaped association between the mean BP and adverse clinical outcomes. These findings suggested that BPV should be a risk factor for adverse outcomes after ischemic stroke, which provided new insight into BP management strategy.

Blood Pressure Goals in Acute Stroke

Antihypertensive treatment is highly effective in both primary and secondary prevention of stroke. However, current guideline recommendations on the blood pressure goals in acute stroke are clinically empirical and generally conservative. Antihypertensive treatment is only recommended for severe hypertension. Several recent observational studies showed that the relationship between blood pressure and unfavorable clinical outcomes was probably positive in acute hemorrhagic stroke but J- or U-shaped in acute ischemic stroke with undetermined nadir blood pressure. The results of randomized controlled trials are promising for blood pressure management in hemorrhagic stroke but less so in ischemic stroke. A systolic blood pressure goal of 140 mm Hg is probably appropriate for acute hemorrhagic stroke. The blood pressure goal in acute ischemic stroke, however, is uncertain, and probably depends on the time window of treatment and the use of revascularization therapy. Further research is required to investigate the potential benefit of antihypertensive treatment in acute stroke, especially with regard to the possible reduction of blood pressure variability and more intensive blood pressure lowering in the acute and subacute phases of a stroke, respectively.