ACE-PAS evaluated the Assure WCD, which provides autonomous detection and defibrillation for ventricular arrhythmias. It can also detect and record other clinically significant arrhythmias. The modern wearable defibrillator system received FDA approval in 2021.
The study marks the largest prospective, real-world study of wearable defibrillators, the company said. It confirmed the safety and effectiveness of Assure in clincial practice. Kirkland, Washington-based Kestra shared findings at the American Heart Association (AHA) Scientific Sessions 2025 in New Orleans.
Dr. Jeanne E. Poole, professor of medicine at the University of Washington and principal investigator, said the study delivered real-world evidence on how Asusre performs in routine care. It also provides contemporary data describing the risk of life-threatening ventricular tachycardia and fibrillation in diverse populations with reduced cardiac function.
“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,” Poole said. “These patients may have significant recovery of heart function during a waiting period of one to six months, such that a permanently implanted defibrillator is not indicated. The Assure WCD should be considered to protect patients at elevated risk of sudden cardiac death during this vulnerable time.”
More on the study findings from Kestra
The study enrolled 21,612 patients across the U.S. Key findings demonstrated consistent safety, effectiveness and compliance in real-world use, the company said.
Findings included 100% successful conversion for ventricular tachycardia and fibrillation (VT/VF) events. This surpassed the prespecified performance goal, achieving the primary effectiveness endpoint. The study also met its primary safety endpoint, observing an inappropriate-shock rate of 0.0065 per patient-month. This came in below the prespecified performance goal and confirmed a strong safety profile.
Kestra also reported minimal false alarms, with 94% of patients experiencing no false positive shock alarms. Assure also provided critical protection, with 2.6% of patients experiencing at least one life-threatening VT/VF event within only a few months. The company said this highlighted the importance of protection in this vulnerable population.
Assure facilitated the detection of high-rate AFib in 4.2% of patients (35% previously undiagnosed) and severe bradycardia/asystole in 0.3%, enabling the potential of timely intervention.
Patients also demonstrated high compliance levels, wearing the device for a median of more than 23 hours per day. One-third continued use beyond 90 days as well.
“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. By pairing proven performance with connected, data-driven insight, Kestra is redefining what’s possible in wearable protection and advancing evidence-based innovation.”
