Aberrant autonomic pattern during the post-exercise recovery phase in long QT syndrome patients.

Anna Lundström,Steen Jensen,Marcus Karlsson,Urban Wiklund,Annika Rydberg,Lucy Law

doi:10.1016/j.autneu.2021.102897

Anna Lundström, Steen Jensen + Show 4 more

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https://doi.org/10.1016/j.autneu.2021.102897

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Journal: Journal of the autonomic nervous system	Publication Date: Dec 1, 2021
Citations: 2	License type: cc-by

Affiliation: Umeå University

Abstract

It is well-established that the autonomic nervous system (ANS) plays a central role in arrhythmogenesis. During and after exercise the ANS is particularly active, and since long QT syndrome (LQTS) patients have an increased risk of lethal arrhythmias during physical activity, it is important to investigate the autonomic function in these patients. In this study we investigate the ANS response during and after exercise in LQTS patients and healthy age and sex matched controls. Forty-four genotype-verified adult LQTS patients and forty-four healthy age- and sex-matched controls performed a submaximal bicycle exercise stress test. Heart rate recovery (HRR) and heart rate variability (HRV) were analyzed from registered electrocardiogram (ECG) and vector electrocardiogram (VCG) recordings collected throughout rest, exercise and in the post-exercise phase. LQTS patients had a slower HRR than controls at 1- and 4-min post-exercise (p<0.001). During the post-exercise phase, LQTS patients had a lower total power (p<0.001), low frequency power (p<0.001) and high frequency power (p<0.001) than controls. In the same phase, LQTS patients off betablocker (BB) treatment showed a lower high frequency power (p=0.01) and different low frequency/high frequency ratio (p=0.003) when comparing with LQTS patients on BB treatment. The parasympathetic effect on both HRR and HRV after exercise appears depressed in this LQTS patient cohort compared to healthy controls. This indicates an aberrant ANS response during the post-exercise phase which might be compensated by BB treatment. Our findings emphasize the importance of performing further investigations to identify the role of the ANS in LQTS arrhythmogenesis.

Highlights

Congenital long QT syndrome (LQTS) is an inherited cardiac ion channelopathy resulting in prolonged cardiac repolarization and an increased risk for life-threatening cardiac events, such as arrhythmias and sudden cardiac death (SCD) (Schwartz et al, 1975)
Forty-six LQTS patients were recruited for assessment, two registrations were excluded due to ventricular arrhythmias during exercise
This study demonstrates that patients with LQTS show an aberrant pattern of cardiac autonomic response during the post-exercise recovery phase compared to healthy controls

Summary

Introduction

Congenital long QT syndrome (LQTS) is an inherited cardiac ion channelopathy resulting in prolonged cardiac repolarization and an increased risk for life-threatening cardiac events, such as arrhythmias and sudden cardiac death (SCD) (Schwartz et al, 1975). Many studies have demonstrated that the autonomic nervous system (ANS) is involved in LQTS, for example, it is known that an increase in sympathetic activity often triggers arrhythmias, and that betaadrenergic blocking and left cardiac denervation are effective treat ments (Liu et al, 2005; Moss et al, 2000). Heart rate variability (HRV) is a frequently used method to monitor the balance between sympathetic-parasympathetic interaction of the ANS. Abnormalities in HRV during daily activity and night-time sleep have been found in studies of LQTS patients (Morita et al, 1996; Porta et al, 2015; Shamsuzzaman, 2003).

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