Kestra Medical Technologies has announced groundbreaking results from the ASSURE WCD Clinical Evaluation Post-Approval Study (ACE-PAS), the largest prospective real-world study of wearable defibrillators ever conducted. The study, presented at the American Heart Association Scientific Sessions 2025 in New Orleans, enrolled 21,612 patients across the United States and demonstrated exceptional safety and effectiveness of the ASSURE Wearable Cardioverter Defibrillator in clinical practice.
Study Achieves Perfect Conversion Success Rate
The ACE-PAS study met its primary effectiveness endpoint with remarkable results, achieving 100% successful conversion for ventricular tachycardia and fibrillation (VT/VF) events, surpassing the prespecified performance goal. This perfect conversion rate represents a significant milestone in wearable defibrillator technology and provides compelling evidence for the device's life-saving potential.
"ACE-PAS delivers robust, real-world evidence on how the ASSURE WCD performs in routine care and provides contemporary data describing the risk of life-threatening ventricular tachycardia and fibrillation in diverse populations with reduced cardiac function," said Jeanne E. Poole, MD, Professor of Medicine at the University of Washington and Principal Investigator.
Exceptional Safety Profile Confirmed
The study also met its primary safety endpoint with an inappropriate shock rate of 0.0065 per patient-month, falling below the prespecified performance goal and confirming a strong safety profile. Notably, 94% of patients experienced no false positive shock alarms, ensuring confidence and comfort during device wear.
High-Risk Population Benefits from Critical Protection
The study revealed that 2.6% of patients experienced at least one life-threatening VT/VF event within only a few months of enrollment, underscoring the importance of wearable defibrillator protection during vulnerable recovery periods. Dr. Poole emphasized that "life-threatening arrhythmias can occur early in patients with low ejection fraction who have recently experienced a myocardial infarction, undergone coronary revascularization, or have been newly diagnosed with heart failure."
Patients in the study demonstrated exceptional compliance, wearing the device for a median of more than 23 hours per day, with one-third continuing use beyond 90 days. This high adherence rate highlights the device's practicality in real-world, long-term care settings.
Additional Clinical Insights Revealed
Beyond its primary defibrillation function, the ASSURE system facilitated detection of other clinically relevant arrhythmias. The device identified high-rate atrial fibrillation in 4.2% of patients, with 35% of these cases being previously undiagnosed. Additionally, severe bradycardia or asystole was detected in 0.3% of patients, enabling potential timely clinical interventions.
Implications for Clinical Practice
"These results reinforce the critical role wearable device monitoring and therapy can play in protecting patients during periods of elevated risk," said Brian Webster, President and Chief Executive Officer of Kestra Medical Technologies. "As the largest and most contemporary study of its kind, ACE-PAS provides compelling evidence that may help inform future updates to clinical practice—particularly around how physicians identify and protect patients at early risk of sudden cardiac death."
The ACE-PAS study enrolled patients from November 2021 through July 2025, with primary endpoints including overall VT/VF shock conversion success and inappropriate shock rate. Additional measures evaluated first shock conversion success, median daily wear time, and false alarm rate, providing comprehensive real-world performance data for this next-generation wearable cardioverter defibrillator system.
