AMBULATORY BLOOD PRESSURE 6 MONTHS POST STROKE IS A BETTER PREDICTOR OF WHITE MATTER HYPERINTENSITIES THAN CLINIC BLOOD PRESSURE

Objective: Stroke remains the most common cause of acquired disability, with secondary prevention a key focus of care, and hypertension the leading modifiable risk factor. Use of early out of office measurements such as ambulatory blood pressure (ABP) will assist in hypertension management and better risk stratify patients than clinic blood pressure (BP). Increased background white matter hyperintensities (WMH) in stroke patients often relate to poorly controlled risk factors preceding the event and higher risk of recurrence. We examined the relationship between WMH severity and ABP profile at six months post stroke. Design and method: This was a prospective study of patients admitted with acute ischaemic or haemorrhagic stroke. Baseline clinical data included stroke type, aetiology, risk factors, demographic and socioeconomic data. All participants had MRI brain performed as part of routine stroke workup. T2 FLAIR sequences were rated by two independent raters using the Fazekas visual scale. ABP was carried out using SpaceLabs OnTrak device, giving variables including day and night mean BP etc. These were correlated with Fazekas scores. Statistical analysis was performed using SAS software. Results: Forty-one patients (14 female) with mean age 61.8 (14.6) years were enrolled. The majority (90%) had ischaemic strokes and 69% were functionally independent (Modified Rankin Score 0-2) at six months post stroke. Those with greater WMH had higher BP at follow up but the differences were greater when assessed by ABP compared to clinic measurements – mean nighttime BP (126.6 vs 111.0 mmHg, p = 0.01), mean daytime BP (136.5 vs 123.4 mmHg, p = 0.02) – compared to clinic BP (138.6 vs 127.0 mmHg, p = 0.09). Ambulatory arterial stiffness index (AASI), a surrogate measure of arterial stiffness, was higher in those with more WMH (0.56 vs 0.41, p < 0.01). Conclusions: Effective secondary prevention is a real challenge in stroke care. ABP usage allows for greater risk stratification post event, based on mean pressures and indices, and prompts appropriately aggressive targeted BP management. Follow up studies like these show that despite initial BP management some patients continue to have suboptimal hypertension control post stroke.