Multiscale complexity analysis of the cardiac control identifies asymptomatic and symptomatic patients in long QT syndrome type 1.
The study assesses complexity of the cardiac control directed to the sinus node and to ventricles in long QT syndrome type 1 (LQT1) patients with KCNQ1-A341V mutation. Complexity was assessed via refined multiscale entropy (RMSE) computed over the beat-to-beat variability series of heart period (HP) and QT interval. HP and QT interval were approximated respectively as the temporal distance between two consecutive R-wave peaks and between the R-wave apex and T-wave end. Both measures were automatically taken from 24-hour electrocardiographic Holter traces recorded during daily activities in non mutation carriers (NMCs, n = 14) and mutation carriers (MCs, n = 34) belonging to a South African LQT1 founder population. The MC group was divided into asymptomatic (ASYMP, n = 11) and symptomatic (SYMP, n = 23) patients according to the symptom severity. Analyses were carried out during daytime (DAY, from 2PM to 6PM) and nighttime (NIGHT, from 12PM to 4AM) off and on beta-adrenergic blockade (BBoff and BBon). We found that the complexity of the HP variability at short time scale was under vagal control, being significantly increased during NIGHT and BBon both in ASYMP and SYMP groups, while the complexity of both HP and QT variability at long time scales was under sympathetic control, being smaller during NIGHT and BBon in SYMP subjects. Complexity indexes at long time scales in ASYMP individuals were smaller than those in SYMP ones regardless of therapy (i.e. BBoff or BBon), thus suggesting that a reduced complexity of the sympathetic regulation is protective in ASYMP individuals. RMSE analysis of HP and QT interval variability derived from routine 24-hour electrocardiographic Holter recordings might provide additional insights into the physiology of the cardiac control and might be fruitfully exploited to improve risk stratification in LQT1 population.
Gruppo Ospedaliero San Donato Foundation, Milan, Italy; Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy.
Vlasta
V
Bari
Department of Electronic Engineering, Universidad de San Buenaventura, Cali, Colombia.
José F
JF
Valencia
Department of Automatic Control, Center for Biomedical Engineering Research, Universitat Politècnica de Catalunya, Barcelona, Spain.
Montserrat
M
Vallverdú
Center for Cardiac Arrhythmias of Genetic Origin, IRCCS Istituto Auxologico Italiano, Centro Diagnostico San Carlo, Milan, Italy.
Giulia
G
Girardengo
Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy; Department of Anesthesia and Intensive Care, IRCCS Humanitas Clinical and Research Center, Rozzano, Italy.
Andrea
A
Marchi
IRCCS Humanitas Clinical and Research Center, Rozzano, Italy.
Tito
T
Bassani
Department of Automatic Control, Center for Biomedical Engineering Research, Universitat Politècnica de Catalunya, Barcelona, Spain.
Pere
P
Caminal
Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy.
Sergio
S
Cerutti
Department of Medicine and Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America.
Alfred L
AL
George
Department of Internal Medicine, University of Stellenbosch, Stellenbosch, South Africa.
Paul A
PA
Brink
Center for Cardiac Arrhythmias of Genetic Origin, IRCCS Istituto Auxologico Italiano, Centro Diagnostico San Carlo, Milan, Italy; Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany.
Lia
L
Crotti
Center for Cardiac Arrhythmias of Genetic Origin, IRCCS Istituto Auxologico Italiano, Centro Diagnostico San Carlo, Milan, Italy.
Peter J
PJ
Schwartz
Department of Biomedical Sciences for Health, University of Milan, Milan, Italy; IRCCS Galeazzi Orthopedic Institute, Milan, Italy.
Alberto
A
Porta
D004562:Electrocardiography; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D051657:KCNQ1 Potassium Channel / Q000235:genetics*; D020125:Mutation, Missense / Q000235:genetics; D029597:Romano-Ward Syndrome / Q000235:genetics* / Q000503:physiopathology; D012849:Sinoatrial Node / Q000503:physiopathology*; D018709:Statistics, Nonparametric
D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human