Safety threshold of R-wave amplitudes in patients with implantable cardioverter defibrillator

• Published in: Heart (British Cardiac Society) Vol. 102; no. 20; pp. 1662 - 1670
• Main Authors: Lillo-Castellano, J M, Marina-Breysse, Manuel, Gómez-Gallanti, Alfonso, Martínez-Ferrer, J B, Alzueta, Javier, Pérez-Álvarez, Luisa, Alberola, Arcadi, Fernández-Lozano, Ignacio, Rodríguez, Anibal, Porro, Rosa, Anguera, Ignacio, Fontenla, Adolfo, González-Ferrer, J J, Cañadas-Godoy, Victoria, Pérez-Castellano, Nicasio, Garófalo, Daniel, Salvador-Montañés, Óscar, Calvo, Conrado J, Quintanilla, Jorge G, Peinado, Rafael, Mora-Jiménez, Inmaculada, Pérez-Villacastín, Julián, Rojo-Álvarez, J L, Filgueiras-Rama, David
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group LTD 15.10.2016
• Subjects: Action Potentials; Adult; Aged; Cardiac arrhythmia; Cardiomyopathy; Defibrillators, Implantable; Delayed Diagnosis; Electric Countershock - adverse effects; Electric Countershock - instrumentation; Electrocardiography - methods; Female; Heart Conduction System - physiopathology; Heart Rate; Humans; Male; Middle Aged; Patient Safety; Predictive Value of Tests; Prosthesis Design; Registries; Remote Sensing Technology - methods; Risk Factors; Signal processing; Signal Processing, Computer-Assisted; Spain; Telemetry - methods; Time Factors; Treatment Outcome; Ventricular Fibrillation - diagnosis; Ventricular Fibrillation - physiopathology; Ventricular Fibrillation - therapy
• DOI: 10.1136/heartjnl-2016-309295
• ISSN: 1355-6037

ObjectiveA 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.MethodsData 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.ResultsWe 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.ConclusionsBaseline R-wave amplitudes ≤2.5 mV during follow-up of patients with ICDs may lead to high risk of delayed detection of VF.Trial registration numberNCT01561144; results.