Atrial fibrillation (AF) is the commonest cardiac arrhythmia and a quietly growing epidemic as people live longer. 3% of Ontarians have AF, including 6% of those in their 70’s, and 10% of those in their 80’s. Annually, over 10,000 Ontarians receive an AF diagnosis. Their morbidity and mortality from cardiovascular disease is high. Catheter ablation is an invasive treatment for AF that is 70% effective. Only 4500 Ontarians receive it yearly. Waitlists of 1-2 years are common. Thus, most patients with AF don’t receive ablation, and rely on electrical cardioversion (ECV), the commonest way normal heart rhythm is restored from AF.
Our study will determine optimal electrode position and the value of manual pressure on the electrodes. Thousands of ECVs are done yearly in Ontario, thus any increases in efficacy lead to hundreds more successful procedures. This benefits patients directly and results in fewer hospital admissions for AF, which are the major driver of AF-related healthcare costs.

Introduction:
Atrial fibrillation (AF) affects millions worldwide with increasing prevalence, and carries substantial morbidity, mortality and healthcare resource utilization. Emerging research shows restoration and maintenance of sinus rhythm is associated with numerous benefits including better quality of life, cardiac function, lower thromboembolic risk and survival. Current CCS guidelines support electrical cardioversion (ECV) for rhythm-control. However, evidence is limited regarding the role of nonpharmacological co-interventions, including electrode placement and manual pressure on the electrodes. Our meta-analysis has demonstrated a trend to benefit of anterolateral (AL) over anteroposterior (AP) placement, and for the use of manual pressure.
Methods:
This is a pragmatic trial comparing AL and AP electrode placement, and the use of pressure versus none in individuals refractory to first shock. Adults undergoing elective ECV of AF are randomized to AL vs AP position. If unsuccessful, they are randomized to addition of manual
pressure versus not on the second shock. Clinicians may perform subsequent shocks using whichever technique they wish.
Intended enrolment is 1500. The primary outcome will be first shock success for AL vs AP. The secondary outcomes will include second shock success for manual pressure versus not, and overall shock success for AL vs AP. Subgroup analyses will be conducted based on factors
including BMI, gender, duration of AF, heart size and function, and premedication. Techniques used for the subsequent shocks will be described qualitatively.
The trial is registered at Clinicaltrials.gov (NCT05511389).
Status:
This study is approved by the Hamilton Integrated Research Ethics Board and received funding from the McMaster University Department of Medicine, Hamilton Academic Health Sciences Organization and Cardiovascular Network of Canada. Approximately 100 participants have been enrolled since February 2023.

This study is ongoing