Abstract 14021: Similar Patterns and Proportions of Ventricular Tachycardia Initiation With Pacing in Patients With CRT-D versus ICD
Introduction: Pacing for bradycardia in ICDs has been suggested to be potentially proarrhythmic by facilitating short-long-short (SLS) sequences. CRT-D with its high volume pacing may be similarly proarrhythmic. We hypothesized that there may be a difference in the proportion of pacing-facilitated VT episodes initiated by CRT-D vs. ICD devices in the MADIT-CRT trial.
Methods: The initiating sequences (last 5 beats) of all episodes submitted to the MADIT-CRT EGM core-lab and adjudicated as being monomorphic VT prior to the 1st of January 2009 were analyzed by their stored EGMs. Episodes were classified as being sudden onset, extrasystolic or paced/fused depending on the morphology of the initiating beat of the VT. They were also classified as non-pacing associated (pacing absent), pacing associated (pacing present without SLS sequence), pacing permitted (pauses passively allowed by the pacing mode and parameters), and pacing facilitated (pauses initiated or terminated actively by pacing stimuli). Treatment allocation was then unblinded and episodes were grouped as being from a CRT-D or ICD . The chi-square statistic was used to compare differences between the two groups.
Results: A total of 338 episodes from 130 patients were analyzed. 253 episodes were from CRT-Ds and 85 episodes from ICDs. Comparing CRT-D to ICD, there was no significant difference in mean VT CL, prematurity index or morphology of onset of VT, being extrasystolic in 33.2% vs 41.2%, sudden onset in 62.5% vs 58.5% and fused with pacing in 4.3% vs 0% for CRT-D vs. ICD. As expected, there were differences in pacing and non-pacing associated initiation that are in keeping with the presence of mandatory pacing in CRT-D. Despite increased pacing in CRT-D devices, there was no significant difference in the proportion of episodes that were pacing facilitated (CRT-D 8.7%; ICD 8.2%; p=ns).
Conclusion: CRT-D is not associated with an increased proportion of pacing facilitated episodes of ventricular tachycardia when compared against ICD in patients with NYHA Class I and II heart failure with an EF<30%, and QRS>0.13s.
- © 2011 by American Heart Association, Inc.