A new electrogram-based diagnostic algorithm to improve the left ventricular effective pacing detection corrected a non-response to cardiac resynchronization therapy pacing

We present a case of a 79-year-old male, non-responder to cardiac resynchronization therapy (CRT) despite the classic pacing counters indicating 99.3% biventricular (BiV) pacing. A new EGM-based diagnostic algorithm was used to uncover poor delivery of CRT pacing. The left ventricle (LV) cathode –right ventricle (RV) Coil electrogram (EGM) corresponding to each paced beat was analysed by the algorithm which automatically determined if the EGM had a QS/QS-r morphology and accordingly classified the paced beat as effective or ineffective. If CRT pacing is effective, the electrogram recorded from the pacing site should have a QS/QS-r morphology corresponding to initiation of activation from the pacing site. The BiV pacing in our case was 99.3% but the new diagnostic indicated only 7.8 % effective CRT pacing. The panel shows initial positive deflection when the right-left ventricle (VV) delay was programmed to 20 ms (LV first) (leftPanel A). In the rightPanelB after changing the VV delay to 80  ms, we can see how the deflection changes to be initially negative, after a long interval of capture latency, suggesting an issue with the tissue in the area of the pacing cathode. With these programming changes, we observed an increase in effective CRT pacing from 7.8% to 97.0%.
Source: Europace - Category: Cardiology Source Type: research