Causes of impaired biventricular pacing in cardiac resynchronization devices with left ventricular sensing

Abstract

Background Loss of biventricular stimulation can result in nonresponse to cardiac resynchronization therapy (CRT). Problems associated with the left ventricular (LV) lead and LV sensing can be challenging to detect and their incidence is unclear. The purpose of this study was to investigate mechanisms of loss of biventricular pacing due to LV lead‐ and LV sensing‐associated problems. Methods In this bicentric study, CRT patients were surveilled using a novel remote monitoring algorithm from Biotronik (Germany) that registers LV electrograms (EGMs) during intermittent loss of resynchronization. The episodes were analyzed to assess the mechanisms of resynchronization interruptions. Results We analyzed 582 EGMs from 61 patients. During a median follow‐up of 6 months, 59% of the patients had such episodes. The majority of the episodes (61%) were related to inappropriate inhibition of LV pacing, mostly due to upper rate lock‐in caused by LV sensing (58%). In contrast, 8% of episodes showed intermittent loss of LV capture, which was identified thanks to LV sensing. The remaining 31% of episodes were due to physiological reasons for resynchronization interruptions (eg, supraventricular tachycardia [18%], premature beats [8%], and others [5%]). Patients with CRT interruption episodes had lower resynchronization rates (median: 98.5% vs 100%, P = .044). Conclusions Inadequate programming (active LV sensing with T‐wave protection) is the main cause of impaired resynchronization in devices with LV sensing. In general, we recommend the deactivation of the LV T‐wave protection function.

Loss of cardiac synchronization due to automatic sense testing

“…If a period of interrupted CRT pacing has a duration of 15 min, there is a loss of approximately 1% CRT pacing on a daily basis. To obtain maximum benefit, CRT pacing should be as high as 98% or higher 6 . Losing 2% by interrupted CRT leaves not much room for loss of CRT due to any event that may occur (NSVT, PVCs, and slow VT episodes or atrial fibrillation with fast conduction to the ventricles).…”

“…The CRT pacing group contains different events so all events need to be reviewed. Reasons for CRT-interrupt other than sense-testing are slow VT, PVCs, and atrial fibrillation or atrial tachycardia with fast conduction to the ventricles 5,6 (Figure 3).…”

Induction of a fast ventricular tachycardia by a CRT-D device. What is the mechanism? Device Rounds

“…If LVTP is off, the LVURI will still be initiated by LVp events or inhibited LVp events but not by LVs events. In this respect, some workers have advocated turning off the LVTP function to prevent desynchronization or so-called CRT pacing interrupt (3).…”