Ventricular Rate Monitoring as a Tool to Predict and Prevent Atrial Fibrillation-Related Inappropriate Shocks in Heart Failure Patients Treated With Cardiac Resynchronisation Therapy Defibrillators

Study Questions:

Can inappropriate implantable cardioverter-defibrillator (ICD) shocks due to atrial fibrillation (AF) with a rapid ventricular response (VR) be predicted and prevented?


The data in this study were gathered retrospectively from 1,404 patients in Italy enrolled in an ICD registry. All patients had an ICD with cardiac resynchronization therapy. Stored electrograms associated with episodes identified by the ICD as ventricular tachycardia/ventricular fibrillation were analyzed. An uncontrolled VR during AF was defined as a mean VR >80 bpm and a maximum VR >110 bpm.


During a median follow-up of 31 months, AF lasting >10 minutes occurred in 40% of patients. Twelve percent of patients received only appropriate ICD shocks, 5% received only inappropriate shocks, and 2% received both appropriate and inappropriate shocks. AF was the cause of the inappropriate shock in 59% of patients with inappropriate shocks. The prevalence of AF-related inappropriate shocks was 5% at 3 years. The median ventricular cycle length of AF episodes that triggered inappropriate shocks was 300 ms. The strongest independent predictors of inappropriate shocks were a history of AF and an uncontrolled VR during AF. An ICD alarm set at a mean VR of 90 bpm during AF would have triggered an alert in 44/60 patients at a minimum interval of 12 days before the inappropriate shocks.


The authors concluded that remote monitoring of VR during AF in patients with an ICD potentially could prevent a majority of AF-related inappropriate shocks.


AF-detection algorithms have reduced, but not eliminated the risk of AF-related inappropriate ICD shocks. ICD alerts potentially could further reduce this risk by alerting physicians that stricter rate control is necessary >1 week before an inappropriate shock.

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