The study is a prospective, randomized, single-blinded, sham-controlled trial. All recruited patients will undergo a 4-week pre-cardioversion phase of medical optimization (including anticoagulation assessment/initiation, initiation of Amiodarone at 200mg daily, and rate-control medications targeting a resting heart rate of <100 bpm). An activity monitor is provided to patients to be worn during waking hours for nine days. A baseline echocardiogram is also performed (if not available within previous 6 months) during this pre-cardioversion phase.
One day prior to the day of cardioversion, the patient will have a 12-lead ECG. If the patient is in sinus rhythm (chemical cardioversion due to Amiodarone) they will be exited from the study and referred back to their MRP cardiologist. If the patient is in AF, they will be randomized electronically using web-based software (Dacima, Montreal, Canada) to "shock" or "sham shock". This will not be revealed to investigators and will be put in a closed envelope and questionnaires will be administered.
During the day of the cardioversion procedure, following anaesthesia administration, the unblinded team (non-MRP cardiologist / anesthesiologist will open the envelope indicating which arm the patient has been randomized to. Other members of the team will step out of the room. The unblinded non-MRP cardiologist will call out as per usual "All clear", following which a shock is delivered as per the Ottawa Cardioversion Protocol in the "shock" arm. Otherwise, no shock is delivered in the "sham shock" arm. Following the intervention, telemetry is discontinued by the unblinded team prior to patient restoration of consciousness. The unblinded team in the day unit will refrain from providing the patient with information regarding which arm they were randomized to. For the purpose of the patient chart and related documentation, a standardized template will be provided to document the process but not the actual intervention, as to maintain patient blinding. A patch Holter monitor is to be applied and worn for rest of study (4 weeks).
After 4 weeks post-cardioversion, a blinded healthcare professional will re-administer a series of questionnaires. At the end of the trial (4 weeks), an ECG will be performed and the patients will be unblinded and told their results. A follow-up (telephone or in-person) will be undertaken at 6 weeks with the patients' MRP cardiologist for discussion of further treatment.