A Computational Study on the Relation between Resting Heart Rate and Atrial Fibrillation Hemodynamics under Exercise

TL;DR

This study uses a computational model to explore how resting heart rate influences hemodynamic responses during exercise in atrial fibrillation patients, suggesting lower resting HR may be more beneficial.

Contribution

It provides novel insights into the relationship between resting HR and exercise hemodynamics in AF patients using a computational approach.

Findings

Lower resting HR results in smaller increases in pulmonary venous pressure during exercise.

Higher resting HR leads to greater systemic arterial pressure increases during exertion.

Slower resting HR may be preferable for better hemodynamic stability during exercise.

Abstract

Aims. Clinical data indicating a heart rate (HR) target during rate control therapy for permanent atrial fibrillation (AF) and assessing its eventual relationship with reduced exercise tolerance are lacking. The present study aims at investigating the impact of resting HR on the hemodynamic response to exercise in permanent AF patients by means of a computational cardiovascular model. Methods. The AF lumped-parameter model was run to simulate resting (1 Metabolic Equivalent of Task-MET) and various exercise conditions (4 METs: brisk walking; 6 METs: skiing; 8 METs: running), considering different resting HR (70 bpm for the slower resting HR-SHR simulations, and 100 bpm for the higher resting HR-HHR simulations). To compare relative variations of cardiovascular variables upon exertion, the variation comparative index (VCI) - the absolute variation between the exercise and the resting values in SHR simulations referred to the absolute variation in HHR simulations -was calculated at each exercise grade (VCI4, VCI6 and VCI8). Results. Pulmonary venous pressure underwent a greater increase in HHR compared to SHR simulations (VCI4 = 0.71, VCI6 = 0.73 and VCI8 = 0.77), while for systemic arterial pressure the opposite is true (VCI4 = 1.15, VCI6 = 1.36, VCI8 = 1.56). Conclusions. The computational findings suggest that a slower, with respect to a higher resting HR, might be preferable in permanent AF patients, since during exercise pulmonary venous pressure undergoes a slighter increase and systemic blood pressure reveals a more appropriate increase.