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Temporal decline in defibrillation thresholds with an active pectoral lead system
E J Rashba1, M R Olsovsky, S R Shorofsky
1Division of Cardiology, University of Maryland School of Medicine, Baltimore, Maryland 21201-1595, USA. erashba@medicine.umaryland.edu
Journal of the American College of Cardiology
|October 5, 2001
Summary
Defibrillation thresholds (DFTs) significantly declined after implantation with active pectoral lead systems. Routine defibrillation testing may not be needed in the first two years post-implantation.
Area of Science:
- Cardiology
- Medical Devices
- Electrophysiology
Background:
- Ventricular defibrillation thresholds (DFTs) can increase over time with certain lead systems.
- Biphasic waveforms attenuate DFT increases, but significant rises still occur in some patients.
- Long-term DFT stability with active pectoral lead systems is not well-established.
Purpose of the Study:
- To characterize temporal changes in defibrillation thresholds (DFTs).
- To evaluate DFTs following implantation of an active pectoral, dual-coil transvenous lead system.
Main Methods:
- Prospective study of 50 patients.
- Uniform testing algorithm, shock polarity, and dual-coil active pectoral lead system.
- DFT measurements at implantation, before discharge, and at long-term follow-up (70 ± 40 weeks).
Main Results:
- Mean DFTs decreased significantly from implantation (9.2 ± 5.4 J) to long-term follow-up (6.9 ± 3.6 J).
- The most pronounced effect was observed in patients with high initial DFTs (≥15 J).
- No patient experienced an inadequate safety margin (<9 J) during follow-up.
Conclusions:
- Active pectoral, dual-coil transvenous lead systems demonstrate a significant decline in DFTs post-implantation.
- No clinically significant DFT increases were observed, suggesting potential for reduced routine testing.
- Routine defibrillation testing may be unnecessary for up to two years post-implantation, barring changes in cardiac substrate or antiarrhythmic drug therapy.