CardioversionMAX-SHOCKNCT06556667
MAX - SHOCK Clinical Trial
A study testing biphasic defibrillator with maximum energy of 200J (® Zoll) in people with Cardioversion and Atrial Fibrillation, run by Ottawa Heart Institute Research Corporation at 1 site in Canada.
Trial summary
Can Electrical Cardioversion (ECV) for AF be improved. It is the preferred method to restore sinus rhythm in patients with AF in whom a rhythm-control strategy is pursued. Hypothesis: ECV success rates will be greater with a biphasic defibrillator with maximum energy of 360J (® Physio-Control) compared to a biphasic… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Cardioversion, Atrial Fibrillation
- What is being tested?
- biphasic defibrillator with maximum energy of 200J (® Zoll)
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 376 participants
- Where
- 1 siteCanada
- Study dates
- 31 Mar 2025to 1 Sep 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Patients age > 18 years.
- Persistent atrial fibrillation.
- Scheduled for elective cardioversion at UOHI
- Patient is within the circle of care of UOHI Electrophysiology staff
Who cannot join
- 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.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Canada1 site, 1 recruiting
- Recruiting
University of Ottawa Heart Institute
Ottawa, Ontario, K1Y 4W7
Dr. Mehrdad Golian, mgolian@ottawaheart.ca
Tammy Knight, tknight@ottawaheart.ca
About this study
Official title: Comparison of Maximum Energy Shocks From Two Defibrillator Vendors MAX - SHOCK- A Randomized Controlled Clinical Trial
Can Electrical Cardioversion (ECV) for AF be improved. It is the preferred method to restore sinus rhythm in patients with AF in whom a rhythm-control strategy is pursued.
Hypothesis:
ECV success rates will be greater with a biphasic defibrillator with maximum energy of 360J (® Physio-Control) compared to a biphasic defibrillator with maximum energy of 200J (® Zoll)
Read the detailed description
Published estimates of ECV success using modern biphasic defibrillators vary considerably but most are limited by small sample sizes. Our pre-intervention ECV success rate of 91.8% was stable over >2.5 years and is comparable to a previous study from our institute11 and to recent estimates from moderately sized studies using contemporary technology. For instance, the Euro Heart Survey on AF reported an ECV success rate of 91% in 424 patients2 and the Biphasic Energy Selection for Transthoracic cardioversion of Atrial Fibrillation (BEST AF) trial reported 89% success in 380 patients.3 The variability in starting shock energy and shock energy escalation observed at our centre prior to implementing the OAFCP is also consistent with reported practices elsewhere. A recent survey of 57 European centres found that nearly two-thirds of hospitals started with a 100 J biphasic shock for AF whereas the remaining third started with 200 J.1 Considerable differences in electrode placement were also reported in this survey with 58.7% of centres using an anterolateral position and the remainder using an anteroposterior approach.1Our investigators and others have previously shown that physicians seldom apply sufficient force even when prompted to do so and even when using handheld paddles.10,16,17 ECV practices at our institute prior to implementing the OAFCP were therefore likely representative of those at most centres.
- Conditions
- Cardioversion, Atrial Fibrillation
- Being tested
- biphasic defibrillator with maximum energy of 200J (® Zoll), biphasic defibrillator with maximum energy of 360J (® Physio-Control)
- Keywords
- defibrillator
- Medical subject headings
- Atrial Fibrillation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
biphasic defibrillator with maximum energy of 200J (® Zoll)Device
Cardioversion
biphasic defibrillator with maximum energy of 360J (® Physio-Control)Device
Cardioversion
| Study group | Role | What they receive |
|---|---|---|
| 200J | Active comparator | biphasic defibrillator with maximum energy of 200J (® Zoll) Receives: Device: biphasic defibrillator with maximum energy of 200J (® Zoll) |
| 360J | Active comparator | biphasic defibrillator with maximum energy of 360J (® Physio-Control) Receives: Device: biphasic defibrillator with maximum energy of 360J (® Physio-Control) |
What is being measured
The primary outcome is the main question the study is designed to answer.
ECV success
ECV success defined as >_2 consecutive sinus beats, or captured atrial-paced beats in patients with implanted cardiac devices, after shock delivery
Measured: 2 seconds
Secondary outcomes (2)
First shock success
Cardioversion is successful without crossover
Measured: 2 seconds
sustained success
sustained sinus or atrial paced rhythm documented on 12-lead electrocardiogram
Measured: 4 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted16 Aug 2024
- Study start31 Mar 2025
- Primary completion1 Sep 2027 (estimated)
- Study completion1 Sep 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for CardioversionStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- two arms will be compared using the Chi squared test
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 376 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Ottawa Heart Institute Research Corporation
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Mehrdad Golian, Principal investigator, Ottawa Heart Institute Research Corporation
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06556667
- Sponsor's protocol ID
- CRRF 6004
- Acronym
- MAX-SHOCK
- Status last verified
- Jan 2026
- First submitted
- 31 Jul 2024
- Last updated
- 3 Feb 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Golian M, Ramirez FD, Cleland M, Aydin A, Green MS, Klein A, Nair G, Nery P, Redpath C, Davis D, Hansom SP, Li Z, Wells GA, Birnie DH. MAX-SHOCK: A Pragmatic Randomized Controlled Trial Comparing Biphasic Defibrillators Used in Routine Cardioversion of Atrial Fibrillation. CJC Open. 2026 Mar 7;8(6):710-714. doi: 10.1016/j.cjco.2026.02.022. eCollection 2026 Jun.
PubMed 42327430
Study at a glance
From the registry record, last updated by the sponsor on 3 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Comparison of Maximum Energy Shocks From Two Defibrillator Vendors MAX - SHOCK- A Randomized Controlled Clinical Trial
- ClinicalTrials.gov ID
- NCT06556667
- Acronym / sponsor ID
- MAX-SHOCK / CRRF 6004
- Conditions
- Cardioversion, Atrial Fibrillation
- Keywords
- defibrillator
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 376 participants (estimated)
- Lead sponsor
- Ottawa Heart Institute Research CorporationUniversity, hospital or other
- Study start
- 31 Mar 2025 (actual)
- Primary completion
- 1 Sep 2027 (estimated)
- Study completion
- 1 Sep 2027 (estimated)
- First posted
- 16 Aug 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Can Electrical Cardioversion (ECV) for AF be improved. It is the preferred method to restore sinus rhythm in patients with AF in whom a rhythm-control strategy is pursued.
Hypothesis:
ECV success rates will be greater with a biphasic defibrillator with maximum energy of 360J (® Physio-Control) compared to a biphasic defibrillator with maximum energy of 200J (® Zoll)
Detailed description
Published estimates of ECV success using modern biphasic defibrillators vary considerably but most are limited by small sample sizes. Our pre-intervention ECV success rate of 91.8% was stable over >2.5 years and is comparable to a previous study from our institute11 and to recent estimates from moderately sized studies using contemporary technology. For instance, the Euro Heart Survey on AF reported an ECV success rate of 91% in 424 patients2 and the Biphasic Energy Selection for Transthoracic cardioversion of Atrial Fibrillation (BEST AF) trial reported 89% success in 380 patients.3 The variability in starting shock energy and shock energy escalation observed at our centre prior to implementing the OAFCP is also consistent with reported practices elsewhere. A recent survey of 57 European centres found that nearly two-thirds of hospitals started with a 100 J biphasic shock for AF whereas the remaining third started with 200 J.1 Considerable differences in electrode placement were also reported in this survey with 58.7% of centres using an anterolateral position and the remainder using an anteroposterior approach.1Our investigators and others have previously shown that physicians seldom apply sufficient force even when prompted to do so and even when using handheld paddles.10,16,17 ECV practices at our institute prior to implementing the OAFCP were therefore likely representative of those at most centres.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (participant)
- Number of arms
- 2
- Model description
- two arms will be compared using the Chi squared test
| Arm | Type | Receives |
|---|---|---|
| 200J | Active comparator | Device: biphasic defibrillator with maximum energy of 200J (® Zoll)biphasic defibrillator with maximum energy of 200J (® Zoll) |
| 360J | Active comparator | Device: biphasic defibrillator with maximum energy of 360J (® Physio-Control)biphasic defibrillator with maximum energy of 360J (® Physio-Control) |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Patients age > 18 years.
- Persistent atrial fibrillation.
- Scheduled for elective cardioversion at UOHI
- Patient is within the circle of care of UOHI Electrophysiology staff
Key exclusion criteria (4 listed)
- 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.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| biphasic defibrillator with maximum energy of 200J (® Zoll)Cardioversion | Device | 200J |
| biphasic defibrillator with maximum energy of 360J (® Physio-Control)Cardioversion | Device | 360J |
Primary outcome
ECV success
Time frame: 2 seconds
ECV success defined as >_2 consecutive sinus beats, or captured atrial-paced beats in patients with implanted cardiac devices, after shock delivery
2 secondary outcomes
First shock success
Time frame: 2 seconds
sustained success
Time frame: 4 hours
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Feb 2026.
- Derived from this study: PubMed 42327430Golian M, Ramirez FD, Cleland M, Aydin A, Green MS, Klein A, Nair G, Nery P, Redpath C, Davis D, Hansom SP, Li Z, Wells GA, Birnie DH. MAX-SHOCK: A Pragmatic Randomized Controlled Trial Comparing Biphasic Defibrillators Used in Routine Cardioversion of Atrial Fibrillation. CJC Open. 2026 Mar 7;8(6):710-714. doi: 10.1016/j.cjco.2026.02.022. eCollection 2026 Jun.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Mehrdad Golian principal investigator
Ottawa Heart Institute Research Corporation
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing biphasic defibrillator with maximum energy of 200J (® Zoll) in people with Cardioversion and Atrial Fibrillation, run by Ottawa Heart Institute Research Corporation at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 3 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Tammy Knight (613-696-7000 ext. 19080, tknight@ottawaheart.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
ECV success (time frame: 2 seconds). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06556667, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Feb 2026.