MAX - SHOCK Clinical Trial

Official title

Comparison of Maximum Energy Shocks From Two Defibrillator Vendors MAX - SHOCK- A Randomized Controlled Clinical Trial

Overview

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.

Interventions

• Device biphasic defibrillator with maximum energy of 200J (® Zoll)
  Cardioversion
• Device biphasic defibrillator with maximum energy of 360J (® Physio-Control)
  Cardioversion

Primary outcome measures

• ECV success [Time frame: 2 seconds]

Secondary outcome measures (2)

• First shock success [Time frame: 2 seconds]
• sustained success [Time frame: 4 hours]

Eligibility 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.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Crossover

Masking

Single blind

Primary purpose

Treatment

Study locations

Canada · 1 center

• University of Ottawa Heart Institute — Ottawa

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. PMID 42327430

Identifiers

NCT: NCT06556667 · CRRF 6004

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗