Optimal Shock Energy for Electrical Cardioversion of Atrial Fibrillation

Optimal Initial Shock Energy for Elective Direct Current Biphasic Electrical Cardioversion of Atrial Fibrillation

Introduction For elective electrical cardioversion of atrial fibrillation, the recommended standard is the administration of a biphasic direct current shock. However, there is considerable variability among physicians regarding the choice of the initial shock energy, as current clinical guidelines do not specify it precisely. The guidelines of American cardiology societies recommend a shock intensity of at least 200 J, while the European Society of Cardiology guidelines do not comment on shock energy at all.

Evidence from a previous randomized clinical trial has shown that using a higher initial shock energy (360 J) is more effective, safe, and reduces the cumulative delivered energy, since lower initial shock energy more frequently requires repeated shocks. The safety of the maximal-energy protocol was demonstrated in this study, among other by the absence of myocardial injury as assessed by cardiac troponin I levels measured 4 hours after electrical cardioversion. However, in this study, the maximal initial shock energy protocol was compared with a low-energy escalating protocol (125-150-200 J), which is no longer supported by current clinical guidelines.

Objective The primary objective of the study is to compare the efficacy (short-term maintenance of sinus rhythm and the need for repeated shocks) of two regimens commonly used in clinical practice: 200-360-360 J and 360-360-360 J.

Secondary objectives are to identify factors that would justify the use of either lower or higher initial shock energy. Another secondary objective is to confirm the safety of the maximal initial shock energy protocol by assessing the biomarker of acute stress (copeptin) in a subpopulation of patients (n = 60).

Methods The main inclusion criterion for the study is the presence of atrial fibrillation or atypical atrial flutter and a clinical indication for electrical cardioversion raised an independent cardiologist. The main exclusion criterion is the presence of typical atrial flutter or focal atrial tachycardia, for which lower shock energy is recommended.

This is a prospective, randomized, single-blind (patient) study in which patients will be randomly assigned in a 1:1:1 ratio either to (i) 200-360-360 J protocol, (ii) 360-360-360 J protocol, or (iii) individualized selection of one of the above protocols based on additional parameters. I one of parameters next parameters is met, the 360-360-360 J protocol will be applied, if not, the 200-360-360 J protocol will be applied: Left atrial size > 55 mm, duration of the arrhythmia > 12 months, BMI > 30 kg/m2, chest circumference > 120 cm.

Since chest dimensions and the amount of subcutaneous fat may influence resistance to electrical current and thereby reduce the delivered electrical energy, chest dimensions and configuration will be evaluated prior to electrical cardioversion in addition to height and weight. The procedure itself (electrical cardioversion) will then be performed according to the standard institutional clinical practice.

Study Overview

• Status: Not yet recruiting
• Conditions: Atrial Fibrillation (AF)
• Intervention / Treatment: Procedure: Direct current biphasic electrical cardioversion; Diagnostic test: blood sampling

• Study Type: Interventional
• Enrollment (Estimated): 400
• Phase: Not Applicable

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Atrial fibrillation
• Atypical atrial flutter
• Indication for elective electrical cardiac version made by independent physician

Exclusion Criteria:

• Typical atrial flutter
• Focal atrial tachycardia

Study Plan

How is the study designed?

Design Details

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

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: 200J protocol; Protocol of 200-360-360J will be applied	Procedure: Direct current biphasic electrical cardioversion; Direct current biphasic electrical cardioversion using Lifepak 20e (Medtronic) external defibrilator will be applied in antero-lateral vector.; Diagnostic test: blood sampling; 6 mL blood samples will be taken from periferal vein before electrical cardiac version and 45 minutes after electrical cardiac version to assess biomarkers of stress and myocardial injury in 60 subjects.
Experimental: 360J protocol; Protocol of 360-360-360J will be applied	Procedure: Direct current biphasic electrical cardioversion; Direct current biphasic electrical cardioversion using Lifepak 20e (Medtronic) external defibrilator will be applied in antero-lateral vector.; Diagnostic test: blood sampling; 6 mL blood samples will be taken from periferal vein before electrical cardiac version and 45 minutes after electrical cardiac version to assess biomarkers of stress and myocardial injury in 60 subjects.
Experimental: Individual protocol; Protocol 200-360-360J or 360-360-360J will be selected according to other criteria	Procedure: Direct current biphasic electrical cardioversion; Direct current biphasic electrical cardioversion using Lifepak 20e (Medtronic) external defibrilator will be applied in antero-lateral vector.; Diagnostic test: blood sampling; 6 mL blood samples will be taken from periferal vein before electrical cardiac version and 45 minutes after electrical cardiac version to assess biomarkers of stress and myocardial injury in 60 subjects.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Presence of sinus rhythm in 1, 5 and 120 minutes after electrical shock.	Presence of sinus rhythm will be assessed by experienced cardiologist using 3-lead ECG monitor (IntelliVue MP, Philips). If it cannot be concluded about the presence of sinus rhythm from 3-lead ECG monitor, standard 12-lead ECG will be performed using SE-1200 Express machine (EDAN).	2 hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cummulative shock energy	Mean shock energy per intervention will be calculated in each arm as a sum of energies of all shocks delivered during one procedure divided by number of procedures.	5 minutes
Myocardial stress and injury	Levels of copeptin and cardiac troponin I or T will be assessed 45 minutes after electrical shock delivery.	45 minutes

Collaborators and Investigators

• Sponsor: Motol and Homolka University Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): May 18, 2026
• Primary Completion (Estimated): December 1, 2028
• Study Completion (Estimated): June 1, 2029

Study Registration Dates

• First Submitted: May 13, 2026
• First Submitted That Met QC Criteria: May 20, 2026
• First Posted (Actual): May 28, 2026

Study Record Updates

• Last Update Posted (Actual): May 28, 2026
• Last Update Submitted That Met QC Criteria: May 20, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Arrhythmias, Cardiac; Pathological Conditions, Signs and Symptoms; Atrial Fibrillation; Investigative Techniques; Specimen Handling; Clinical Laboratory Techniques; Diagnostic Techniques and Procedures; Diagnosis; Punctures; Surgical Procedures, Operative; Blood Specimen Collection
• Other Study ID Numbers: MotolHomolkaUH

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No