20 research outputs found
Mechanisms underlying the autonomic modulation of ventricular fibrillation initiation—tentative prophylactic properties of vagus nerve stimulation on malignant arrhythmias in heart failure
Use of baroreceptor reflex sensitivity in the prediction of risk after myocardial infarction
Vagal stimulation for heart diseases: from animals to men. An example of translational cardiology
Individual autonomic profile contributes to the risk for life-threatening arrhythmias among KCNQ1-A341V mutation carriers
Vagal reflexes following an exercise stress test : A simple clinical tool for gene-specific risk stratification in the Long QT Syndrome
Geneeskunde en GesondheidswetenskappeInterne GeneeskundePlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]
Vagal reflexes following an exercise stress test: a simple clinical tool for gene-specific risk stratification in the long QT syndrome.
Objectives: The study assessed whether heart rate (HR) reduction following an exercise stress test (ExStrT), an easily quantifiable marker of vagal reflexes, might identify high- and low-risk long QT syndrome (LQTS) type 1 (LQT1) patients. Background: Identification of LQTS patients more likely to be symptomatic remains elusive. We have previously shown that depressed baroreflex sensitivity, an established marker of reduced vagal reflexes, predicts low probability of symptoms among LQT1. Methods: We studied 169 LQTS genotype-positive patients < 50 years of age who performed an ExStrT with the same protocol, on and off β-blockers including 47 South African LQT1 patients all harboring the KCNQ1-A341V mutation and 122 Italian LQTS patients with impaired (IKs-, 66 LQT1) or normal (IKs+, 50 LQT2 and 6 LQT3) IKs current. Results: Despite similar maximal HR and workload, by the first minute after cessation of exercise the symptomatic patients in both IKs- groups had a greater HR reduction compared with the asymptomatic (19 ± 7 beats/min vs. 13 ± 5 beats/min and 27 ± 10 beats/min vs. 20 ± 8 beats/min, both p = 0.009). By contrast, there was no difference between the IKs+ symptomatic and asymptomatic patients (23 ± 9 beats/min vs. 26 ± 9 beats/min, p = 0.47). LQT1 patients in the upper tertile for HR reduction had a higher risk of being symptomatic (odds ratio: 3.28, 95% confidence interval: 1.3 to 8.3, p = 0.012). Conclusions: HR reduction following exercise identifies LQT1 patients at high or low arrhythmic risk, independently of β-blocker therapy, and contributes to risk stratification. Intense exercise training, which potentiates vagal reflexes, should probably be avoided by LQT1 patient