Chronotropic response during exercise in patients undergoing cardioneuroablation for reflex asystolic syncope

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Abstract Background Cardioneuroablation is an emerging treatment for reflex asystolic syncope in patients with hypervagal reactivity. This procedure targets the ablation of post-ganglionic endings of the parasympathetic component of the autonomic nervous system (ANS) within the ganglionated plexi located in the epicardial fat and myocardium. The modification of parasympathetic activity may extend beyond resting heart rate (HR), as the autonomic nervous system plays a crucial role in regulating the heart's response to exercise. Understanding of these changes provides valuable insight into the influence of ANS modulation on HR dynamics during physical exertion. Objective This study aims to evaluate the impact of cardioneuroablation on resting HR and HR response during exercise. Methods and Results Fifty-nine patients (35 female, 24 male; mean age: 40 ± 13 years) who qualified for cardioneuroablation underwent symptom-limited cardiopulmonary exercise testing on a treadmill a day before (CPET 1) and one year after the procedure (CPET 2). Exercise capacity was measured as oxygen uptake at peak exercise (peak VO₂). The analyzed heart rate parameters included resting HR, peak HR, HR reserve achieved (peak HR – resting HR), HR reserve expected (maximum predicted HR – resting HR), percentage of predicted maximal HR achieved (%MPHR), chronotropic index calculated as the ratio of HR reserve achieved and predicted, and HR recovery at one minute. The maximum predicted HR was calculated as 220—age in years. CPET 2 showed significant changes compared to CPET 1. Resting heart rate increased (88.7 ± 13.4 bpm to 94.2 ± 12.3 bpm, p < 0.01), and peak exercise heart rate also increased (158.6 ± 19.5 bpm to 162.1 ± 17.7 bpm, p = 0.03). Expected heart rate reserve decreased (90 ± 21 bpm to 86 ± 19 bpm, p < 0.01), but achieved heart rate reserve did not change significantly (69.8 ± 18.6 bpm vs. 68.0 ± 16.3 bpm, p = 0.39). Percent of maximum predicted heart rate increased (87 ± 15% to 91 ± 9%, p < 0.01). The chronotropic index showed a trend towards a significant increase (0.78 ± 0.19 vs. 0.82 ± 0.18, p = 0.049). One year after cardioneuroablation, heart rate recovery at one minute decreased (29.6 ± 11.8 bpm vs. 20.0 ± 8.5 bpm, p < 0.01). Peak VO₂ increased (25.61 ± 5.41 mL/kg/min to 28.57 ± 6.34 mL/kg/min, p < 0.01). Conclusion Cardioneuroablation significantly alters HR regulation, leading to a higher resting HR and slower HR recovery. Despite these changes, the chronotropic response during exercise and overall exercise capacity were not impaired one year after the procedure. Further studies with larger sample sizes are necessary to confirm these findings and evaluate the long-term implications of parasympathetic denervation.

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