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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
medicine
Vagal reflexes following an exercise stress test: A simple clinical tool for gene-specific risk stratification in the long QT syndrome
Journal of the American College of Cardiology, Volume 60, No. 24, Year 2012
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Description
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 patients. © 2012 American College of Cardiology Foundation.
Authors & Co-Authors
CROTTI, L.
Italy, Pavia
Università Degli Studi Di Pavia
Italy, Pavia
Fondazione Irccs Policlinico San Matteo
Germany, Oberschleissheim
Helmholtz Center Munich German Research Center for Environmental Health
Spazzolini, Carla
Italy, Pavia
Fondazione Irccs Policlinico San Matteo
Porretta, Alessandra P.
Switzerland, Bellinzona
Ospedale San Giovanni
Dagradi, Federica
Italy, Pavia
Università Degli Studi Di Pavia
Italy, Pavia
Fondazione Irccs Policlinico San Matteo
Taravelli, Erika
Italy, Pavia
Università Degli Studi Di Pavia
Italy, Pavia
Fondazione Irccs Policlinico San Matteo
Petracci, Barbara
Italy, Pavia
Fondazione Irccs Policlinico San Matteo
Vicentini, Alessandro
Italy, Pavia
Fondazione Irccs Policlinico San Matteo
Pedrazzini, Matteo
Italy, Pavia
Fondazione Irccs Policlinico San Matteo
La Rovere, Maria Teresa
Italy, Pavia
Istituti Clinici Scientifici Maugeri Spa – sb
Vanoli, Emilio
Italy, Pavia
Università Degli Studi Di Pavia
Italy, Novara
Clinica San Gaudenzio
Goosen, Althea
South Africa, Stellenbosch
Stellenbosch University
Heradien, Marshall J.
South Africa, Stellenbosch
Stellenbosch University
George, Alfred L.
United States, Nashville
Vanderbilt University
Brink, Paul A.
South Africa, Stellenbosch
Stellenbosch University
Schwartz, Peter J.
Italy, Pavia
Università Degli Studi Di Pavia
Italy, Pavia
Fondazione Irccs Policlinico San Matteo
Saudi Arabia, Riyadh
College of Medicine
South Africa, Cape Town
University of Cape Town
Statistics
Citations: 50
Authors: 15
Affiliations: 10
Identifiers
Doi:
10.1016/j.jacc.2012.08.1009
ISSN:
07351097
e-ISSN:
15583597
Research Areas
Cancer
Genetics And Genomics
Study Design
Case-Control Study