MAX - SHOCK Clinical Trial (MAX-SHOCK)

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)

Study Overview

• Status: Recruiting
• Conditions: Atrial Fibrillation; Cardioversion
• Intervention / Treatment: Device: biphasic defibrillator with maximum energy of 200J (® Zoll); Device: biphasic defibrillator with maximum energy of 360J (® Physio-Control)

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 Type: Interventional
• Enrollment (Estimated): 376
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Tammy Knight; Phone Number: 19080 613-696-7000; Email: tknight@ottawaheart.ca
• Study Contact Backup: Name: David Birnie; Phone Number: 613-696-7000; Email: dbirnie@ottawaheart.ca

Study Locations

• Canada
  • Ontario
    • Ottawa, Ontario, Canada, K1Y 4W7
      • Recruiting
      • University of Ottawa Heart Institute
      • Contact: Dr. Mehrdad Golian; Email: mgolian@ottawaheart.ca
      • Contact: Tammy Knight; Email: tknight@ottawaheart.ca
      • Principal Investigator: Dr. Mehrdad Golian

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: 200J; biphasic defibrillator with maximum energy of 200J (® Zoll)	Device: biphasic defibrillator with maximum energy of 200J (® Zoll); Cardioversion
Active Comparator: 360J; biphasic defibrillator with maximum energy of 360J (® Physio-Control)	Device: biphasic defibrillator with maximum energy of 360J (® Physio-Control); Cardioversion

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
ECV success	ECV success defined as >_2 consecutive sinus beats, or captured atrial-paced beats in patients with implanted cardiac devices, after shock delivery	2 seconds

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
First shock success	Cardioversion is successful without crossover	2 seconds
sustained success	sustained sinus or atrial paced rhythm documented on 12-lead electrocardiogram	4 hours

Collaborators and Investigators

• Sponsor: Ottawa Heart Institute Research Corporation
• Investigators: Principal Investigator: Mehrdad Golian, Ottawa Heart Institute Research Corporation

Study record dates

Study Major Dates

• Study Start (Actual): March 31, 2025
• Primary Completion (Estimated): September 1, 2027
• Study Completion (Estimated): September 1, 2027

Study Registration Dates

• First Submitted: July 31, 2024
• First Submitted That Met QC Criteria: August 14, 2024
• First Posted (Actual): August 16, 2024

Study Record Updates

• Last Update Posted (Actual): February 3, 2026
• Last Update Submitted That Met QC Criteria: January 30, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: defibrillator
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Arrhythmias, Cardiac; Pathological Conditions, Signs and Symptoms; Atrial Fibrillation
• Other Study ID Numbers: CRRF 6004

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No