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

2016; BMJ; Volume: 102; Issue: 20 Linguagem: Inglês

10.1136/heartjnl-2016-309295

1468-201X

José María Lillo-Castellano, Manuel Marina‐Breysse, Alfonso Gómez-Gallanti, JB. Martinez-Ferrer, Javier Alzueta, Luisa Pérez‐Álvarez, Arcadi Garcı́a-Alberola, Ignacio Fernández Lozano, Aníbal Rodríguez, Rosa Porro, Ignacio Anguera, Adolfo Fontenla, Juan José González‐Ferrer, Victoria Cañadas‐Godoy, Nicasio Pérez‐Castellano, Daniel Garófalo, O. Salvador, Conrado J. Calvo, Jorge G. Quintanilla, Rafaél Peinado, Inmaculada Mora-Jiménez, Julián Pérez‐Villacastín, José Luis Rojo‐Álvarez, David Filgueiras‐Rama,

Cardiac Arrhythmias and Treatments

Objective 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. Methods 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. Results 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. Conclusions Baseline 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 number NCT01561144; results.