Fig 1.
Flowchart of the defibrillation safety and efficacy studies.
Flowchart describing objectives, endpoints and sample sizes for the three animal studies and one human study providing a comprehensive assessment of defibrillation safety and efficacy of the new BTE waveform designed for use in a WCD.
Fig 2.
Typical Biphasic Truncated Exponential (BTE) shock waveform.
Graphical representation of the typical BTE waveform showing current as a function of time. I1 = Peak current, I2 = Phase 1 trailing edge current, I3 = Phase 2 peak current, I4 = Phase 2 trailing edge current, T1 = Phase 1 period, T2 = Phase 2 period, T3 = Interphase delay.
Table 1.
SHOCK A and SHOCK B waveform parameters.
Fig 3.
Animal Study #1 experimental setup.
Image illustrating laboratory setup to enable ventricular fibrillation (VF) induction, monitoring and defibrillation in swine. ECG = Electrocardiogram.
Fig 4.
Animal Study #1 shock sequence.
Figure illustrating shock sequence and randomization of shock type for each animal.
Fig 5.
Animal Study #2 experimental setup.
Image illustrating laboratory setup to enable ventricular fibrillation (VF) induction, monitoring and defibrillation in swine. ECG = Electrocardiogram, att = attenuated.
Fig 6.
Animal Study #2 charge voltage determination.
Image illustrating the process to establish the charge voltage for 50% defibrillation success of attSHOCK A and the subsequent calculation of the charge voltage for attSHOCK B at each target impedance. NSR = normal sinus rhythm, att = attenuated.
Fig 7.
Animal Study #2 shock sequence.
Figure illustrating attSHOCK A and attSHOCK B defibrillation shock sequence for each animal. att = attenuated.
Fig 8.
Animal Study #3 experimental setup.
Image illustrating laboratory setup to enable shock delivery during normal sinus rhythm and monitoring in swine. ECG = Electrocardiogram.
Fig 9.
Animal Study #3 shock sequence.
Figure illustrating shock sequence and randomization of shock type for each animal.
Table 2.
Human study eligibility criteria.
Fig 10.
Human study experimental setup.
Anterior and posterior views of the thorax for the human study of the 170J BTE waveform (SHOCK A) in the electrophysiology laboratory. The test system showing the WCD defibrillation unit and adapter module is shown in the lower left. Two sets of defibrillation patches are shown, with the test system connected to the yellow patches and rescue defibrillator connected to the gray patches. The test system pads (yellow) were applied in standard anterior and posterior positions, with the anterior pad in the left parasternal region and the posterior pad in the left infrascapular position. The rescue defibrillation pads (gray) were placed in the standard anterior-apical position on the subject’s torso for defibrillation from a commercially available external defibrillator. Surface ECG was monitored with electrophysiology laboratory recording equipment. WCD = wearable cardioverter defibrillator; ICD = implantable cardioverter defibrillator; EP = Electrophysiology.
Fig 11.
(A) Observed first shock success rates for termination of ventricular fibrillation with attSHOCK A (blue) and attSHOCK B (red) at 50, 85 and 125 ohm impedances. (B) Difference in observed first shock success rates (attSHOCK A–attSHOCK B). At each of the three impedance levels, the mean difference (dot) and the 95% confidence interval of the difference (whiskers) in first shock success rates is shown. attSHOCK A was non-inferior to attSHOCK B as the entire 95% confidence interval of the difference (attSHOCK A–attSHOCK B) in first shock success rates was above the -10% prespecified non-inferiority margin (dotted line). At 85 and 125 ohms, the first shock success rate of attSHOCK A was superior to attSHOCK B as the entire 95% confidence interval of the difference in first shock success rates was above 0%. See text for details.
Table 3.
Animal Study #3 biomarker levels at baseline, 6 hours, and 24 hrs post shock with Tukey-Kramer pairwise comparisons at each time point.
Table 4.
General Linear Mixed Model analysis for Animal Study #3 biomarker levels.
Fig 12.
Human study consort flowchart.
Of the 88 patients assessed for eligibility, 13 met inclusion criteria and consented to enroll in the study. Defibrillation study procedure was completed on all 13 enrolled patients and included in the Intention-to-Treat analysis. Study monitoring identified that an enrolled patient had been prescribed Amiodarone during an emergency room visit (three weeks prior to study enrollment) and continued taking it for 6 days (protocol eligibility deviation). Twelve patients were included in the Per-Protocol analysis.
Table 5.
Human study baseline characteristics.
Table 6.
Human study defibrillation test results.
Table 7.
Human study defibrillation efficacy.