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Potential proarrhythmic effects of biventricular pacing.
Jeffrey M Fish1, Josep Brugada, Charles Antzelevitch
1Masonic Medical Research Laboratory, Utica, New York 13501-1787, USA.
Journal of the American College of Cardiology
|December 20, 2005
Summary
Cardiac resynchronization therapy can improve heart failure symptoms but may increase arrhythmia risk. Reversing left ventricular activation during biventricular pacing prolongs QT intervals and heightens proarrhythmic risks, especially in patients with long QT syndrome.
Area of Science:
- Cardiology
- Electrophysiology
- Heart Failure Research
Background:
- Cardiac resynchronization therapy (CRT) with biventricular pacing improves outcomes in heart failure patients.
- Focus has been on mechanical benefits, with less attention on electrical consequences of altered activation sequences.
- Reversing left ventricular activation may have proarrhythmic effects.
Purpose of the Study:
- To review the understanding of left ventricular repolarization heterogeneity.
- To examine how reversed activation sequences amplify repolarization dispersion.
- To discuss the implications for patients undergoing CRT.
Main Methods:
- Review of basic science and clinical studies on ventricular activation and repolarization.
- Analysis of QT interval prolongation and transmural dispersion of repolarization.
- Correlation of findings with proarrhythmic events in CRT patients.
Main Results:
- Reversed left ventricular activation prolongs the QT interval.
- This reversal increases transmural dispersion of repolarization.
- This creates a substrate for re-entrant arrhythmias, particularly in long QT conditions.
Conclusions:
- Biventricular pacing, by altering activation sequence, can be proarrhythmic in susceptible patients.
- Prolonged QT interval exacerbates the proarrhythmic risk associated with CRT.
- Understanding repolarization dynamics is crucial for optimizing CRT safety and efficacy.