ABSTRACT NUMBER: ESOC2026A395 REDUCED AND ELEVATED RESTING HEART RATES PREDICT RISK OF STROKE, INDEPENDENTLY OF ATRIAL FIBRILLATION: A UK BIOBANK ANALYSIS

Abstract Background and aims Elevated heart rate is associated with hypertension and poor cardiovascular health, but low heart rates may reflect either cardiovascular fitness or disease, may predispose to paroxysmal atrial fibrillation (AF) and are associated with increased cerebral pulsatility and thus small vessel disease. However, the relationship with stroke risk is unclear. We determined these relationships in UK Biobank. Methods UK-Biobank is a large, community-based, longitudinal cohort recruiting > 500,000 UK participants since 2007, with face-to-face assessment and healthcare data-linkage. Associations between baseline heart-rate and stroke were determined by incidence rate and Cox proportional hazards regression, unadjusted and adjusted for age, sex and cardiovascular risk factors, including AF at any time. Results Over 13.2 years (6.1 million person-years), 11,733 strokes occurred among 460,554 participants (194/100,000 person-years). Risk of stroke was lowest with baseline heart rates of 60–69 bpm (173/100,000Pyrs) and increased at both low (<50 bpm) and high (≥90 bpm) heart rate (236 and 271/100,000Pyrs), quadratic P < 0.001. After full adjustment, low heart-rate was significantly associated with stroke risk (HR 1.29, 95%CI 1.17–1.43, P < 0.001) as was high heart-rate (HR 1.17, 95%CI 1.08–1.27, P < 0.001). In stratified analyses, the U-shaped pattern was only significant in participants without AF (n = 458,098), with no significant interaction between heart rate and AF (P = 0.078). Conclusions Resting heart rate demonstrates a significantly U-shaped relationship with incident stroke, independent of a diagnosis of AF. Whether low heart rates are a marker of cardiovascular dysfunction or could have a causal role is unclear in the absence of interventional studies. Conflict of interest Dexter Penn: nothing to disclose. Figure 1 - belongs to Methods Figure 2 - belongs to Results