Abstract Body (Do not enter title and authors here): Introduction
Atrial fibrillation (AF) is associated with decreased cardiac output through loss of atrial contribution to ventricular filling and irregular and often rapid ventricular activation with shorter diastolic filling time. These hemodynamic changes may contribute to the variable symptoms and impaired quality of life (QoL) seen in AF. Myocardial oxygen extraction provides a novel mean of assessing the physiological basis behind the QoL in an AF population.
Hypothesis
Myocardial oxygen extraction correlates with the general well-being, AF burden, and AF symptoms score.
Methods
Myocardial arterial (left atrium) blood and venous (coronary sinus) blood were collected from patients undergoing AF ablation. Oxygen extraction was derived from the arterio-venous oxygen content of blood samples (Panel A). Pre-procedural hemoglobin levels were noted. The Atrial Fibrillation Severity Scale (AFSS) was used to assess pre-procedural quality of life measures, which include global well-being (GWB), AF burden, and AF symptoms score. GWB is assessed based on a Likert scale of a maximum of 10. AF burden and symptoms scores are based on a linear scale. AF burden is the sum of AF frequency, duration, and severity, while AF symptoms score is based on the sum of 6 major AF related symptoms which include: palpitations, shortness of breath at rest and during physical activity, fatigue at rest and during physical activity, lightheadedness, and chest pain.
Results
Thirty AF patients were recruited (age was 65 ± 11 years). Fourteen patients (55%) were females, 6 (21%) were in persistent AF, and 8 (28%) had a diagnosis of heart failure. Myocardial oxygen extraction was 9.5 ± 1.9 mL of O2 extracted/dL of blood. The median GWB in patients with oxygen extraction ≤9.5 mL of O2 extracted/dL of blood was 8 (7-9) vs. 5(4-7) (P= 0.005), AF burden was 13(5-20) vs. 21(17-27) (P=0.017), and the AF symptom score was 7(1-12) vs. 13 (6-21) (P= 0.043) (Panel B). There was a negative correlation between oxygen extraction and GWB (r=-0.51; P= 0.005) and a positive correlation with AF burden (r=0.44; P= 0.017) and AF symptom score (r= 0.42; P= 0.024) (Panel C).
Conclusion
In AF patients, greater myocardial oxygen extraction correlates with lower self-reported well-being and higher AF burden and symptom scores. This relationship suggests that increased myocardial oxygen demand may reflect underlying physiological stress contributing to patients’ symptom perception and disease experience.