Absence of significant myocardial injury following elective direct current cardioversion for atrial fibrillation

BACKGROUND Direct current (DC) cardioversion is used to termi -nate cardiac arrhythmias. Current guidelines list cardioversion as a cause of myocardial injury. OBJECTIVE This study determined whether external DC cardiover-sion results in myocardial injury measured by serial changes in high-sensitivity cardiac troponin T (hs-cTnT) and high-sensitivity cardiac troponin I (hs-cTnI). METHODS This was a prospective study of patients undergoing elective external DC cardioversion for atrial fibrillation. hs-cTnT and hs-cTnI were measured precardioversion and at least 6 hours postcardioversion. Myocardial injury was present when there were significant changes in both hs-cTnT and hs-cTnI. RESULTS Ninety-eight subjects were analyzed. Median cumulative energy delivered was 121.9 (interquartile range [IQR] 102.2-302.7) J. Multiple cases 23 (23.5%) required 300 J or more. Maximum cu-mulative energy delivered was 2455.1 J. There were small signifi-cant changes in both hs-cTnT (median precardioversion 12 [IQR 7-19) ng/L], median postcardioversion 13 [IQR 8-21] ng/L; P < .001) and hs-cTnI (median precardioversion 5 [IQR 3-10) ng/L], median postcardioversion 7 [IQR 3.6-11) ng/L; P < .001). Results were similar in patients with high-energy shocks and did not vary based on precardioversion values. Only 2 (2%) cases met criteria for myocardial injury. CONCLUSION DC cardioversion resulted in a small but statistically significant changes in hs-cTnT and hs-cTnI in 2% of patients studied irrespective of shock energy. Patients with marked troponin eleva-tions after elective cardioversion should be assessed for other causes of myocardial injury. It should not be assumed the myocar-dial injury was from the cardioversion.