Comparing higher-energy versus standard biphasic shocks for cardioversion of atrial fibrillation
Comparison of Maximum Energy Shocks From Two Defibrillator Vendors MAX - SHOCK- A Randomized Controlled Clinical Trial
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
| Phase | Not applicable |
|---|---|
| Study type | Interventional |
| Enrollment | 376 (estimated) |
| Ages | 18 Years and up |
| Sex | All |
| Sponsor | Ottawa Heart Institute Research Corporation Academic / other |
| Locations | 1 site (Ottawa, Ontario) |
| Trial ID | NCT06556667 on ClinicalTrials.gov |
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.
Who should consider this trial
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.
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.
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 performed: 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.
Eligibility criteria
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 this trial is running
Ottawa, Ontario
- 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
How to participate
- Review the eligibility criteria above with your treating physician.
- Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
- Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.