Low Heart Rate Is Associated with Cerebral Pulsatility after TIA or Minor Stroke

• Published in: Annals of neurology Vol. 92; no. 6; pp. 909 - 920
• Main Authors: Webb, Alastair J.S., Wartolowska, Karolina A., Li, Linxin, Rothwell, Peter M.
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01-12-2022; Wiley Subscription Services, Inc
• Subjects: Age; Animals; Blood flow; Blood pressure; Blood Pressure - physiology; Blood vessels; Cardiovascular disease; Coronary artery disease; Dementia disorders; EKG; Electrocardiography; Flow velocity; Geese; Heart diseases; Heart Rate; Humans; Ischemic Attack, Transient - diagnostic imaging; Middle Cerebral Artery; Monitoring; Patients; Stiffness; Stroke; Stroke - complications; Telemedicine; Transient ischemic attack; Vascular diseases; Velocity
• ISSN: 0364-5134; 1531-8249
• DOI: 10.1002/ana.26480

Objective
Beta‐blockers are beneficial in coronary artery disease but less so in stroke prevention and dementia, potentially due to reduced heart rate (HR). Cerebral pulsatility is strongly associated with cerebral small vessel disease (SVD) and may be increased by lower diastolic pressures resulting from longer cardiac cycles.
Methods
Patients 4–6 weeks after TIA or non‐disabling stroke (Oxford Vascular Study) underwent 5 minutes continuous monitoring of blood pressure (BP), electrocardiogram (ECG), and middle cerebral artery flow velocity (transcranial ultrasound). Beat‐to‐beat relationships between HR, blood pressure and Gosling's pulsatility index (MCA‐PI) are reported as beta‐coefficients from general linear models for each individual.
Results
Across 759 patients, average MCA‐PI during monitoring was associated with lower HR and diastolic BP (DBP) and greater systolic BP (SBP) (∆MCA‐PI per 10 bpm/mmHg: −0.02, −0.04, 0.03, all p < 0.001), with HR particularly associated with low end‐diastolic cerebral velocity (0.86, p = 0.014). Beat‐to‐beat HR was strongly associated with concurrent low DBP and high SBP, potentially mediating the association with greater beat‐to‐beat cerebral pulsatility (average ∆MCA‐PI vs HR/DBP/SBP unadjusted: −0.062, −0.052, 0.0092; adjusted for concurrent BP: −0.039, −0.11, 0.041). The beat‐to‐beat association between HR and MCA‐PI increased with age, beta‐blockers, arterial stiffness, low HR (age > 70 + HR < 65 vs age < 70 + HR > 65: −0.081 vs −0.024, interaction p < 0.001), and severe SVD on MRI (age > 70 + severe vs age < 70 + none: −0.087 vs −0.047, interaction p = 0.03), with interactions between age, severe SVD, and low HR synergistically increasing MCA‐PI.
Interpretation
Low HR is associated with greater cerebral pulsatility in patients with SVD, potentially mediated by lower diastolic blood flow and representing a novel potential treatment target. ANN NEUROL 2022;92:909–920