Background
Atrial fibrillation (AF) alters heart rate, rhythm regularity, and atrial contraction, which may contribute to an increased risk of heart failure. While rate and rhythm control target different aspects of these disturbances, their specific effects on left ventricular (LV) function remain unclear.
Objective
To predict the independent and combined contribution of heart rate, rhythm regularity and atrial contraction to LV function in AF patients.
Methods
We predicted LV ejection fraction (EF) and stroke volume (SV) in 10 whole-heart patient-specific AF patient models while varying heart rate, rhythm regularity and effectiveness of atrial contraction.
AF was modeled as a fast, irregular heart rate with no atrial contraction. Pharmacological and paced rate control were modeled as a slow irregular and regular heart rate without atrial contraction, respectively, while rhythm control had a slow, regular heart rate with atrial contraction.
Results
Rhythm control resulted in a greater improvement in LVEF than pharmacological rate control compared to AF (+5.1 ± 0.4% vs +2.8 ± 0.3%, P<0.01). Paced rate control was equivalent to pharmacological rate control in terms of LVEF (+2.6 ± 0.4% vs +2.8 ± 0.3%). Atrial contraction did not improve ventricular function in the presence of an irregular heart rate (pharmacological rate: +2.8 ± 0.3% vs rhythm with irregular heart rate: +2.7 ± 0.3%).
Conclusion
Rhythm control provides superior improvements in LV function compared to rate control. However, restoring sinus rhythm may yield limited benefits to LV function when atrial contraction is ineffective or when heart rate is irregular.