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Does defibrillation threshold increase as left ventricular ejection fraction decreases?
Jesus E Val-Mejias1, Ashish Oza
1Galichia Heart Hospital, 2600 N. Woodlawn Avenue, Wichita, KS 67226, USA. val-y-mexia@hotmail.com
Summary
Defibrillation thresholds (DFTs) minimally change with decreasing left ventricular ejection fraction (LVEF) in advanced cardiac disease patients. This study found no significant increase in DFTs as LVEF declined, suggesting device efficacy is maintained across a broad LVEF spectrum.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Advanced cardiac disease is characterized by hypertrophy, fibrosis, scarring, dilatation, and conduction delays.
- The relationship between decreasing left ventricular ejection fraction (LVEF) and defibrillation thresholds (DFTs) remains incompletely understood.
- Previous studies have approached this question indirectly or insufficiently.
Purpose of the Study:
- To investigate whether defibrillation thresholds (DFTs) increase as left ventricular ejection fraction (LVEF) decreases in patients with advanced cardiac disease.
- To stratify DFTs across various LVEF ranges, expanding on prior research.
- To provide a clearer understanding of DFT behavior in relation to cardiac function.
Main Methods:
- Retrospective analysis of DFT data from 230 patients across three acute, multicentre, randomized studies.
- DFTs were recorded with the SVC coil ON and optimized pulse-width waveforms (3.5 ms membrane time constant).
- Patients were stratified into LVEF groups (LVEF > or = 46% and LVEF < or = 25%).
Main Results:
- DFT estimates showed a minor increase from 395.2 +/- 115 V (LVEF > or = 46%) to 425.8 +/- 117.6 V (LVEF < or = 25%) as LVEF decreased.
- These changes in DFT estimates were not statistically significant.
- Only 3% of patients exhibited an elevated DFT (>20 J).
Conclusions:
- Defibrillation thresholds (DFTs) change minimally, if at all, across a broad range of left ventricular ejection fraction (LVEF).
- Results align with prior studies showing no significant DFT differences between ICD and CRT-D recipients.
- No significant DFT differences were observed between primary and secondary prevention indications, irrespective of LVEF.
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