Blood Pressure Variability in Patients With Acute Ischemic Stroke: Is It Worth Measuring?

In recent years, blood pressure variability (BPV) has emerged as a risk factor for cardiovascular morbidity and mortality in the general population and in hypertensive patients, independently of blood pressure (BP) measurements.1–3 In contrast, it remains unclear whether BPV predicts the outcome of patients admitted with acute ischemic stroke.4–7 An early meta-analysis of 8 studies (n = 6,778) reported that systolic BPV predicts poor functional outcome but included patients with both ischemic and hemorrhagic stroke.5 A more recent meta-analysis of 11 studies (n = 3,520) also suggested that systolic BPV predicts poor functional outcome at 3 months but included only patients who underwent endovascular thrombectomy.6 Whether BPV predicts the longer-term outcome of unselected patients with acute ischemic stroke is still uncertain. A new study by Yousufuddin et al. published in the present issue of the American Journal of Hypertension provides more data in this area.8 The authors enrolled 862 consecutive adult patients (mean age 75 ± 15 years) who survived to discharge after hospitalization for first-ever acute ischemic stroke.8 All patients had serial BP measurements in the nondominant and nonparetic arm at least every 4 hours for the duration of hospitalization.8 BPV was evaluated by estimating the SD and the coefficient of variation of systolic BP.8 In this study, neither index of systolic BPV was associated with the incidence of all-cause readmission or death during a 1-year follow-up.8 How can we reconcile the discrepant results between the well-conducted study by Yousufuddin et al.8 and previous studies in the field? Even though BPV was shown to predict the functional outcome of patients at 3 months after stroke, it has been shown that functional outcome is not strongly related to the risk of recurrent stroke or mortality during longer-term follow-up.9 Indeed, in another recent study, BPV during the acute phase of ischemic stroke predicted functional outcome at 12 months.7 In addition, the assessment of functional outcome is subjective and is limited by substantial interobserver variability.10 It is also possible that BPV has greater predictive value in selected patients, e.g., in those who undergo thrombolysis, where BP control is more strict, than in unselected subjects with acute ischemic stroke.6,11 On the other hand, it is also possible that other indices of systolic BPV or diastolic BPV, which were not evaluated in the study by Yousufuddin et al.,8 might predict mortality and recurrent stroke in patients with acute ischemic stroke. Given the conflicting evidence regarding the predictive value of BPV during the acute phase of ischemic stroke, which are the future perspectives in this field? Even though frequent measurement of BP is relatively inexpensive, strained healthcare systems in an era of COVID-19 pandemic and financial crisis have to prioritize resource allocation. In addition, studies that evaluated the effects of antihypertensive treatment on the outcome of patients admitted with acute ischemic stroke yielded largely disappointing results.12,13 More well-designed studies, like the study by Yousufuddin et al.,8 are needed to definitely answer the question whether BPV predicts short- and long-term outcomes of patients with acute ischemic stroke. Whether the use of antihypertensive agents that reduce BPV more effectively, particularly calcium channel blockers, might improve the outcome of ischemic stroke also needs to be evaluated14. Until more data are available, it appears unlikely that the evaluation of BPV during the acute phase of ischemic stroke will substantially affect treatment decisions or risk stratification. The authors declared no conflict of interest.