Transthoracic Transmitral Atrial Flow is Independently Associated with Ischemic Stroke Risk in Paroxysmal Atrial Fibrillation

Atrial fibrillation (AF) significantly increases the risk of ischemic stroke. This study evaluates whether transmitral atrial flow velocity (MVA), measured non-invasively via transthoracic echocardiography (TTE), predicts stroke risk in AF patients.To assess the independent association between TTE-derived MVA and stroke incidence in paroxysmal AF patients and its value in refining risk stratification, especially in low-risk groups.This cohort study included 10,150 paroxysmal AF patients from 2010 to 2021. The primary outcome was hospitalization for ischemic stroke. Multivariable Cox regression analyses adjusted for CHA₂DS₂-VASc scores evaluated the relationship between MVA and stroke risk.Over a mean follow-up of 4.26 ± 3.52 years, 2,419 (23.8%) patients developed ischemic strokes (5.59% per 100 person-years). In multivariable analysis, adjusting for CHA₂DS₂-VASc score, MVA was independently associated with stroke incidence. Every 10 cm/s reduction in MVA velocity conferred 4% higher stroke risk (adjusted hazard ratio [HR] 0.96 [0.94-0.97], <i>P</i> < 0.001). AF patients with MVA < 50 cm/s had a 39% increase in stroke risk compared to those with MVA ≥ 50 cm/s (adjusted HR 1.39 [1.22-1.58], <i>P</i> < 0.001). In patients with a CHA₂DS₂-VASc score of 0 or 1, the stroke incidence increased from 1.33 to 2.28% when they had MVA < 50 cm/s, which was similar to that of patients with a CHA₂DS₂-VASc score of 2 points (2.51%).TTE-derived MVA independently predicts stroke risk in paroxysmal AF patients. Incorporating MVA enhances risk stratification and guides targeted stroke prevention, particularly in low-risk populations.