| Abstract | BACKGROUND: Restitution through intracardiac pacing has been used to assess arrhythmia vulnerability. We examined whether analyses of sequential beat-to-beat QT and TQ interval measures can be used to quantify ECG restitution changes under normal sinus rhythm. METHODS: The QT, R-R and TQ intervals were examined 22.5 hour Holter monitoring before and after oral sotalol in normal male and female volunteers. Additionally, comparisons were made to those observed in the time-matched dataset prior to torsades de pointes in a heart diseased patient that received a single dose of sotalol. RESULTS: Sotalol increased QT, R-R and TQ intervals 71, 101, and 125 ms after 160 mg (n = 38) and 194, 235, and 135 ms after 320 mg (n = 19) during maximum plasma concentrations, respectively. The percentage of beats with a QT/TQ ratio >1 was reduced 25% over the entire 22.5 hours after sotalol and the lower TQ interval boundary (5th quantile) was increased 22-30%. In contrast, 99% of the beats prior to torsades de pointes had a QT/TQ ratio > 1 and the median TQ interval was below the lower 98% confidence bounds of normals before and after sotalol. CONCLUSIONS: ECG restitution changes are quantifiable under varying states (nocturnally, beta-adrenergic blockade, QT prolongation) in healthy subjects. |
| Authors | Anthony A Fossa, Todd Wisialowski, Kimberly Crimin, Eric Wolfgang, Jean-Philippe Couderc, Martin Hinterseer, Stefan Kaab, Wojciech Zareba, Fabio Badilini, Nenad Sarapa
(Affiliation: Pfizer Global Research and Development, Groton, Connecticut 06340, USA. anthony.a.fossa at pfizer.com)
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| Journal | Annals of noninvasive electrocardiology : the official journal of the International Society for Holter and Noninvasive Electrocardiology, Inc
(Ann Noninvasive Electrocardiol)
Vol. 12
Issue 4
Pg. 338-48
(Oct 2007)
ISSN: 1082-720X United States |
| PMID | 17970959
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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| Chemical References |
- Anti-Arrhythmia Agents
- Sotalol
|
| Topics |
- Adolescent
- Adult
- Anti-Arrhythmia Agents
(pharmacology)
- Electrocardiography, Ambulatory
- Female
- Humans
- Long QT Syndrome
(chemically induced, physiopathology)
- Male
- Middle Aged
- Sotalol
(pharmacology)
- Statistics, Nonparametric
- Torsades de Pointes
(chemically induced, physiopathology)
|
