Safety threshold of R-wave amplitudes in patients with implantable cardioverter defibrillator.
A safety threshold for baseline rhythm R-wave amplitudes during follow-up of implantable cardioverter defibrillators (ICD) has not been established. We aimed to analyse the amplitude distribution and undersensing rate during spontaneous episodes of ventricular fibrillation (VF), and define a safety amplitude threshold for baseline R-waves.



Data were obtained from an observational multicentre registry conducted at 48 centres in Spain. Baseline R-wave amplitudes and VF events were prospectively registered by remote monitoring. Signal processing algorithms were used to compare amplitudes of baseline R-waves with VF R-waves. All undersensed R-waves after the blanking period (120 ms) were manually marked.



We studied 2507 patients from August 2011 to September 2014, which yielded 229 VF episodes (cycle length 189.6±29.1 ms) from 83 patients that were suitable for R-wave comparisons (follow-up 2.7±2.6 years). The majority (77.6%) of VF R-waves (n=13953) showed lower amplitudes than the reference baseline R-wave. The decrease in VF amplitude was progressively attenuated among subgroups of baseline R-wave amplitude (≥17; ≥12 to <17; ≥7 to <12; ≥2.2 to <7 mV) from the highest to the lowest: median deviations -51.2% to +22.4%, respectively (p=0.027). There were no significant differences in undersensing rates of VF R-waves among subgroups. Both the normalised histogram distribution and the undersensing risk function obtained from the ≥2.2 to <7 mV subgroup enabled the prediction that baseline R-wave amplitudes ≤2.5 mV (interquartile range: 2.3-2.8 mV) may lead to ≥25% of undersensed VF R-waves.



Baseline R-wave amplitudes ≤2.5 mV during follow-up of patients with ICDs may lead to high risk of delayed detection of VF.



NCT01561144; results.
Myocardial Pathophysiology Area, Fundación Centro Nacional de Investigaciones Cardiovasculares, Carlos III (CNIC), Madrid, Spain Department of Signal Theory and Communications, Telematics and Computing, Universidad Rey Juan Carlos (URJC), Madrid, Spain.
J M
JM
Lillo-Castellano
Myocardial Pathophysiology Area, Fundación Centro Nacional de Investigaciones Cardiovasculares, Carlos III (CNIC), Madrid, Spain.
Manuel
M
Marina-Breysse
Department of Cardiology, Hospital Universitario La Paz, Madrid, Spain.
Alfonso
A
Gómez-Gallanti
Department of Cardiology, Hospital Universitario de Araba, Vitoria, Spain.
J B
JB
Martínez-Ferrer
Department of Cardiology, Hospital Universitario Virgen de la Victoria, Málaga, Spain.
Javier
J
Alzueta
Department of Cardiology, Hospital Universitario A Coruña, La Coruña, Spain.
Luisa
L
Pérez-Álvarez
Department of Cardiology, Hospital Universitario Virgen de la Arrixaca, Murcia, Spain.
Arcadi
A
Alberola
Department of Cardiology, Hospital Universitario Puerta de Hierro, Madrid, Spain.
Ignacio
I
Fernández-Lozano
Department of Cardiology, Hospital Universitario de Canarias, Santa Cruz de Tenerife, Spain.
Anibal
A
Rodríguez
Department of Cardiology, Hospital San Pedro de Alcántara, Cáceres, Spain.
Rosa
R
Porro
Department of Cardiology, Hospital de Bellvitge, Barcelona, Spain.
Ignacio
0000-0001-6988-3487
I
Anguera
Department of Cardiology, Hospital 12 de Octubre, Madrid, Spain.
Adolfo
A
Fontenla
Department of Cardiology, Hospital Clínico San Carlos, Madrid, Spain.
J J
JJ
González-Ferrer
Department of Cardiology, Hospital Clínico San Carlos, Madrid, Spain.
Victoria
V
Cañadas-Godoy
Department of Cardiology, Hospital Clínico San Carlos, Madrid, Spain.
Nicasio
N
Pérez-Castellano
Department of Cardiology, Hospital Universitario La Paz, Madrid, Spain.
Daniel
D
Garófalo
Department of Cardiology, Hospital Universitario La Paz, Madrid, Spain.
Óscar
Ó
Salvador-Montañés
Myocardial Pathophysiology Area, Fundación Centro Nacional de Investigaciones Cardiovasculares, Carlos III (CNIC), Madrid, Spain Department of Electrical Engineering, Universitat Politècnica de Valencia, Valencia, Spain.
Conrado J
CJ
Calvo
Myocardial Pathophysiology Area, Fundación Centro Nacional de Investigaciones Cardiovasculares, Carlos III (CNIC), Madrid, Spain Department of Cardiology, Hospital Clínico San Carlos, Madrid, Spain.
Jorge G
JG
Quintanilla
Department of Cardiology, Hospital Universitario La Paz, Madrid, Spain.
Rafael
R
Peinado
Department of Signal Theory and Communications, Telematics and Computing, Universidad Rey Juan Carlos (URJC), Madrid, Spain.
Inmaculada
I
Mora-Jiménez
Department of Cardiology, Hospital Clínico San Carlos, Madrid, Spain.
Julián
J
Pérez-Villacastín
Department of Signal Theory and Communications, Telematics and Computing, Universidad Rey Juan Carlos (URJC), Madrid, Spain.
J L
JL
Rojo-Álvarez
Myocardial Pathophysiology Area, Fundación Centro Nacional de Investigaciones Cardiovasculares, Carlos III (CNIC), Madrid, Spain Department of Cardiology, Hospital Clínico San Carlos, Madrid, Spain.
David
D
Filgueiras-Rama
D000200:Action Potentials; D000328:Adult; D000368:Aged; D017147:Defibrillators, Implantable; D057210:Delayed Diagnosis; D004554:Electric Countershock / Q000009:adverse effects / Q000295:instrumentation*; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D061214:Patient Safety; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D012042:Registries; D058998:Remote Sensing Technology / Q000379:methods; D012307:Risk Factors; D012815:Signal Processing, Computer-Assisted; D013030:Spain; D013686:Telemetry / Q000379:methods; D013997:Time Factors; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*