Comparing higher-energy versus standard biphasic shocks for cardioversion of atrial fibrillation
Official title: Comparison of Maximum Energy Shocks From Two Defibrillator Vendors MAX - SHOCK- A Randomized Controlled Clinical Trial
Run by Ottawa Heart Institute Research Corporation · NCT06556667 · Data updated 2026-11-12
This trial will test whether using a 360J biphasic defibrillator works better than a 200J device to restore normal heart rhythm in adults with persistent atrial fibrillation scheduled for elective cardioversion.
Quick facts
| Study type | Interventional |
|---|---|
| Ages | 18 Years and up |
| Sex | All |
| Enrollment | 376 (estimated) |
| Sponsor | Ottawa Heart Institute Research Corporation Academic / other |
| Locations | 1 site (Ottawa, Ontario) |
| Status | Recruiting |
| Started | March 31, 2025 |
| Main results expected | September 1, 2027 |
| Study ends | September 1, 2027 |
| Registry record updated | February 3, 2026 |
| Trial ID | NCT06556667 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Adults over 18 with persistent atrial fibrillation who are scheduled for elective cardioversion at the University of Ottawa Heart Institute and are under UOHI electrophysiology care are the intended participants.
✕Probably not a fit
Patients with a known left‑atrial appendage thrombus, contraindications to anticoagulation, those enrolled in another randomized trial, or those who do not meet the listed inclusion criteria are not eligible and would not receive potential benefit from this comparison.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
Patients scheduled for elective electrical cardioversion at the University of Ottawa Heart Institute will receive cardioversion using either a biphasic defibrillator with a 360J maximum (Physio‑Control) or a biphasic defibrillator with a 200J maximum (Zoll), and immediate success rates will be compared. Eligible participants are adults with persistent atrial fibrillation who are within the circle of care of UOHI electrophysiology staff and have no left atrial appendage thrombus or anticoagulation contraindication. The primary outcome is restoration of sinus rhythm after cardioversion; procedures will follow local standardized electrode placement and sedation protocols. The trial builds on prior reports of ~89–92% success with contemporary biphasic devices and aims to determine whether higher available maximum energy improves first‑attempt or overall conversion rates.
Why it matters
Potential benefit: If successful, using a defibrillator with a 360J maximum could increase the chance of restoring normal rhythm with fewer shocks and fewer repeat procedures.
How similar studies have gone: Previous moderately sized studies and registries report cardioversion success rates around 89–92% with modern biphasic devices, but direct head‑to‑head comparisons of 360J versus 200J devices are limited.
Who can join: the full rules
Show full inclusion / exclusion criteria
Inclusion Criteria: * Patients age \> 18 years. * Persistent atrial fibrillation. * Scheduled for elective cardioversion at UOHI * Patient is within the circle of care of UOHI Electrophysiology staff Exclusion Criteria: * Known left-atrial appendage thrombus. * Contraindication to appropriate anticoagulation. * Patient is included in another randomized clinical trial. * Patient does not meet all of the above listed inclusion criteria.
Where it's running
-
University of Ottawa Heart Institute
Ottawa, Ontario, Canada Recruiting
Study contacts
- Principal investigator: Mehrdad Golian — Ottawa Heart Institute Research Corporation
- Study coordinator: Tammy Knight
- Email: tknight@ottawaheart.ca
- Phone: 613-696-7000
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.