Researchers are trying to determine if heart injury occurs in subjects who undergo direct current cardioversion.

External transthoracic direct current (DC) cardioversion is a commonly used method of terminating cardiac arrhythmias. Conventional wisdom indicates that external DC cardioversion causes myocardial injury. Previous research has shown that DC cardioversion resulted in myocardial injury as evidenced by increased levels of cardiac troponin, even though those changes were modest. Many of these studies evaluated monophasic defibrillators and older, less sensitive cardiac troponin assays. The current standard is now to use modern biphasic defibrillators and new high sensitivity cardiac troponin assays (hs-cTnT). It is conceivable that the newer defibrillators may not cause myocardial injury. It would be important to understand if myocardial injury occurs in this setting and its approximate magnitude as it would the interpretation of hs-cTnT values in patients and therefore influenced diagnoses. It may be if a threshold energy level can be identified that is would also influence the choice of energy used to deliver the shock in this situation.

A previous preliminary study documented no evidence of myocardial injury after elective DC cardioversion with modern day defibrillators. We aim to validate and expand that study here at Mayo Clinic Rochester.

Inclusion Criteria:

• Patients who are undergoing elective direct current cardioversion, either externally or via the patient's internal cardioverter-defibrillator

Exclusion Criteria:

• Patients under age 18
• Patients with myocardial infarction, coronary artery bypass grafting or any invasive cardiac procedure in the previous six weeks
• Pregnant patients
• Patients who cannot provide informed consent because of cognitive dysfunction

Adult male and females age 18 and above identified from the electronic medical record (EMR) calendar of patients scheduled for an elective direct current cardioversion.