Impact of Fusion Avoidance on Performance of the Automatic Threshold Tracking Feature in Dual Chamber Pacemakers: A Multicenter Prospective Randomized Study

Abstract

The Autocapture algorithm enables automatic capture verification on a beat-by-beat basis by recognizing the evoked response signal following each pacemaker stimulus. The algorithm intends to increase patient safety while decreasing energy consumption. However, the occurrence of fusion beats, particularly during dual chamber pacing, may limit the energy saving effect of Autocapture. The aim of this multicenter, prospective, randomized study was to evaluate the impact of the Fusion Avoidance (FA) algorithm on the incidence of fusion beats. Thirty-eight patients (mean age 69 +/- 13 years) with intrinsic AV conduction who were implanted with an Affinity DR were studied. After programming a PV/AV delay of 120/190 ms, patients were randomized to FA On or Off. Each group was further randomized with respect to activation of the AutoIntrinsic Conduction Search (AICS) algorithm. The total number of beats, ventricular paced beats, fusion beats, backup pulses, and threshold searches were analyzed from 24-hour Holter recordings. The number of total beats was comparable in both FA groups. The number of total ventricular paced beats, fusion beats, backup pulses, and threshold searches were significantly reduced in the FA On group (% reduction: 68% P < 0.001, 75% P < 0.01, 95% P < 0.01, and 94% P < 0.05, respectively). The number of ventricular paced beats with full capture was significantly reduced when AICS was activated (P < 0.05). In conclusion, the FA algorithm substantially reduces the amount of ventricular paced beats, fusion beats, unnecessary backup pulses and threshold searches, and therefore, provides added benefits in energy saving obtained by Autocapture.

Basic Properties And Clinical Applications Of The Intracardiac

“…Such autoregulation mechanisms would have a great impact in the clinical setting, ensuring the stimulation of the appropriate target and reducing the incidence of false alarms of capture loss, which still affect the performance of most capture monitoring systems by inducing a useless increase in energy consumption. [21][22][23] As the care for the quality of the pacing therapy is progressively rising, the strategic relevance of advanced control tools like the iECG correspondingly grows.…”

Automatic Verification of Ventricular Stimulation: Fusion Management Algorithm

“…So, it is the intrinsic conduction search more than the detection of fusion, which is not detected but inferred in case spontaneous AV conduction is found after an elicited back‐up pulse. Fusion Avoidance has proved very effective in patients with normal AV conduction, 13 but its performance has never been tested in patients with spontaneous or drug‐induced AV conduction prolongation. In fact, spontaneous AV conduction may vary substantially from its median value, thus a 100 ms prolongation is often inadequate to avoid unnecessary ventricular stimulation 14,15 .…”

“…Depending on the atrioventricular (AV) interval programming in the presence of spontaneous atrioventricular conduction, the fusion phenomenon may become prevalent, and can cause underdetection of ventricular ER with continuous inappropriate back‐up pulse delivery until the autocapture algorithm is switched off. In the clinical evaluation of Autocapture™‐featured single chamber and dual chamber pacemakers, fusion phenomenon accounted for 87% and 98% of back‐up pulse delivery, respectively 8,13 …”

“…An accurate algorithm of fusion beat management could avoid fusion misclassification, unnecessary back‐up pulses, and increase battery longevity 13 …”

Determination of the Optimal Atrioventricular Interval in Sick Sinus Syndrome During DDD Pacing

“…Furthermore, because PR interval is likely to be shorter than atrial stimulus‐R interval, the proportion of atrial pacing to atrial sensing is very important 27 . Recently, the autointrinsic conduction search option, featured on some DDD pacemakers, performs periodic assessments of AV conduction capability during a single beat AV interval extension 28 . Demonstration of ventricular conduction during the prolonged AV interval permits ongoing AV interval extension if the patient's intrinsic conduction is preferred to ventricular pacing.…”