The impact of atrial fibrillation and stroke risk factors on left atrial blood flow characteristics

Abstract

Aims Altered left atrial (LA) blood flow characteristics account for an increase in cardioembolic stroke risk in atrial fibrillation (AF). Here, we aimed to assess whether exposure to stroke risk factors is sufficient to alter LA blood flow even in the presence of sinus rhythm (SR). Methods and results We investigated 95 individuals: 37 patients with persistent AF, who were studied before and after cardioversion [Group 1; median CHA2DS2-VASc = 2.0 (1.5–3.5)]; 35 individuals with no history of AF but similar stroke risk to Group 1 [Group 2; median CHA2DS2-VASc = 3.0 (2.0–4.0)]; and 23 low-risk individuals in SR [Group 3; median CHA2DS2-VASc = 0.0 (0.0–0.0)]. Cardiac function and LA flow characteristics were evaluated using cardiac magnetic resonance. Before cardioversion, Group 1 displayed impaired left ventricular (LV) and LA function, reduced LA flow velocities and vorticity, and a higher normalized vortex volume (all P < 0.001 vs. Groups 2 and 3). After restoration of SR at ≥4-week post-cardioversion, LV systolic function and LA flow parameters improved significantly (all P < 0.001 vs. pre-cardioversion) and were no longer different from those in Group 2. However, in the presence of SR, LA flow peak and mean velocity, and vorticity were lower in Groups 1 and 2 vs. Group 3 (all P < 0.01), and were associated with impaired LA emptying fraction (LAEF) and LV diastolic dysfunction. Conclusion Patients at moderate-to-high stroke risk display altered LA flow characteristics in SR in association with an LA myopathic phenotype and LV diastolic dysfunction, regardless of a history of AF.

2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

“…4,5 Rapidity of recovery of mechanical atrial systole may be influenced by clinical variables, 37 duration of the antecedent AF episode leading to cardioversion, 5 and the extent of comorbid conditions as risks factors for atrial myopathy. 38…”

Stasis Imaging Predicts the Risk of Cardioembolic Stroke Related to Acute Myocardial Infarction

“…Remarkably, stasis can also be quantified for blood in the left atrium and the left atrial appendage. 33 Because LV systolic dysfunction, atrial myopathy and disturbed intra-atrial flow are very prevalent in patients with embolic stroke of unknown source, 34 stasis imaging may be also useful in this condition. Stasis imaging may also provide insight on the relationship between subclinical LV systolic dysfunction and silent cerebrovascular disease.…”

“…Patients with a primary endpoint showed larger myocardial infarct size by CMR than those patients without endpoint (32 [29-37]% vs. 21 [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]% of total myocardial mass, respectively p= 0.04). Enrollment echocardiographic examinations showed lower values of EF in patients with a primary endpoint (38 [34][35][36][37][38][39][40][41][42][43]%) than in those without endpoint (42 [36-51]%, p= 0.02). Also, apical strain was higher in patients with a primary endpoint than in those free of events: -4.7 [-7.2--3.6] vs -7.9 [-10.1--6.0]% (p< 0.01).…”

Cardiovascular Magnetic Resonance Imaging of Atrial Fibrillation: An Advanced Hemodynamic Perspective

“…LA peak velocity and vorticity were found to be more reproducible and independent of physiological biomarkers than LA mean velocity, LA vortex volume, and blood flow stasis. There was an approach to associate risk factors with LA flow characteristics [46]. This study presented patients with moderate to high CHA 2 DS 2 -VASc scores have impaired LA flow parameters even though they have restored from arrhythmia or have no AF history.…”