MAX - SHOCK Clinical Trial

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.

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.