Can we predict, prevent, and minimize defibrillator shocks? Lessons learned from “remote monitoring”

Abstract

s I o f 9 f Beyond their principal role of successfully detecting and treating ventricular tachycardia (VT) and ventricular fibrillation (VF) with overdrive antitachycardia pacing and defibrillation shocks, modern implantable cardioverter-defibrillators (ICDs) are capable of providing sophisticated pacing and resynchronization therapy. They store enormous amounts of technical and patient-related data, such as arrhythmia burden and heart failure status. Device manufacturers recently introduced “remote monitoring” technology, which allows home transmitters to interrogate devices and to download and transmit collected and stored data via the Internet to a protected network. Remote monitoring not only has rapidly shifted the paradigm in device follow-up but has heightened interest in exploring the wealth of available information to better understand device functionality and disease substrates. Irrespective of the indications for ICD placement, given the associated risk factors and comorbidities, the majority of recipients also would be prone, if they have not already experienced, to develop atrial fibrillation (AF). The presence of AF, with its 5% to 30% incidence in the ICD population, is not merely a “nuisance” because it has many detrimental effects. Paroxysmal, persistent, and permanent AF have hazard ratios (HRs) (95% confidence interval] of 1.3 (0.7–2.5), 1.2 (0.6–2.2), and 1.7 (1.0–2.7), respectively, for mortality and 1.2 (0.6–2.2), 1.1 (0.5–2.4), and 2.4 (1.5–4.0), respectively, for appropriate ICD shocks. A ewly detected AF within the first 3 months of ICD placeent carries a significant risk for death with HR of 2.86 1.02–8.05). In patients with left ventricular dysfunction, persistent AF has been shown to cause appropriate ICD shocks and deterioration of heart failure. Furthermore, AF ay be proarrhythmic. In the Jewel AF trial, 8.6% of all T/VF episodes were found to have AF as a preceding or oncomitant rhythm. Interestingly, for consecutive episodes of VT/VF, time to next episode of VT/VF was longer when AF terminated than when it persisted.