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A four-shock Bayesian up-down estimator of the 80% effective defibrillation dose
R A Malkin1, J M Herre, L McGowen
1Joint Program in Biomedical Engineering at The University of Memphis and the University of Tennessee-Memphis, 38152, USA. ramalkin@cc.memphis.edu
Journal of Cardiovascular Electrophysiology
|July 21, 1999
Summary
A new four-shock protocol accurately estimates the 80% effective defibrillation strength (ED80) for patients. This method improves defibrillation testing accuracy and safety margins for implantable devices.
Area of Science:
- Cardiology
- Biomedical Engineering
- Statistical Modeling
Background:
- Standard defibrillation threshold testing requires extrapolation from ineffective shocks, leading to errors and large safety margins.
- Current methods necessitate large sample sizes for hypothesis testing and significant safety margins for defibrillator implantation.
- A novel, clinically validated statistical model offers a minimum error, four-shock protocol for estimating patient-specific 80% effective defibrillation strength (ED80).
Purpose of the Study:
- To present and validate a minimum error, four-shock defibrillation testing protocol for estimating the 80% effective defibrillation strength (ED80).
- To establish an accurate and efficient method for determining optimal defibrillation voltages for individual patients.
- To provide a reliable tool for both clinical hypothesis testing and defibrillator implantation decisions.
Main Methods:
- A Bayesian statistical model was developed assuming a sigmoidal defibrillation dose-response curve.
- The model informed a minimum predicted error testing protocol using a four-shock Bayesian up-down approach.
- Prospective validation involved 170 patients undergoing voltage-programmed biphasic testing, with attempts at estimated ED80 and ED80 + 100 V.
Main Results:
- The Bayesian up-down protocol successfully estimated the ED80 for patients.
- Testing at the estimated ED80 resulted in successful defibrillation in 84% of 170 patients.
- A 100 V increment above the ED80 (ED80 + 100 V) demonstrated high effectiveness (98%) in 136 patients, indicating an adequate safety margin.
Conclusions:
- The four-shock Bayesian up-down protocol is the first clinical method to accurately predict ED80 voltage.
- A 100 V increment above the estimated ED80 provides a sufficient safety margin for defibrillation.
- This accurate and simple method for estimating effective defibrillation dose is valuable for clinical research and device implantation.