High-Rate Pacing Reduces Variability of Repolarization and Prevents Repolarization-Dependent Arrhythmias in Dogs With Chronic AV Block

Research output: Contribution to journalJournal articleResearchpeer-review

  • Peter Oosterhoff
  • Thomsen, Morten Bækgaard
  • Joep N Maas
  • Nico J M Atteveld
  • Jet D M Beekman
  • Harold V M VAN Rijen
  • Marcel A G VAN DER Heyden
  • Marc A Vos
High-rate pacing may have an inhibitory effect on the initiation of Torsade de Pointes arrhythmias (TdP). However, permanent pacing is only indicated in high-risk patients. We performed a proof of concept study into automatic overdrive pacing for prevention of drug-induced TdP, using short-term variability of repolarization (STV) as a feedback parameter of arrhythmic risk.

Methods and Results: The minimal signal sampling frequency required for measuring STV was determined through computer simulation. Arrhythmogenic response to dofetilide (25 µg/kg/5minutes) was tested at two different paced heart rates (60–65 bpm vs 100–110 bpm) in 7 dogs with chronic atrioventricular block, while recording right and left ventricular (LV) monophasic action potential (MAP) and LV electrogram (EGM). Simulations showed a sampling frequency of 500 Hz is sufficient to capture relevant STV values. High-rate pacing prevented dofetilide-induced TdP seen at the low rate (low: 6/7 vs high: 1/7). At the low rate, STV from LV MAP duration increased before occurrence of spontaneous, ectopic activity and TdP (1.7 ± 0.6–3.0 ± 1.8 ms, P < 0.05), but at the high-rate STV did not change significantly (0.9 ± 0.2–1.5 ± 1.4 ms, NS). Regression analysis showed a close relation between STV calculated from LV MAP and from LV EGM (R2= 0.71).

Conclusions: High-rate pacing increases repolarization reserve in dogs with chronic atrioventricular block, preventing dofetilide-induced TdP. Changes in repolarization reserve are reflected in values of STV.
Original languageEnglish
JournalJournal of Cardiovascular Electrophysiology
Issue number12
Pages (from-to)1384-91
Number of pages8
Publication statusPublished - 1 Dec 2010

ID: 33744508