Cardiac biochemical markers after cardioversion of atrial fibrillation or atrial flutter

Background Cardioversion or defibrillation of cardiac arrhythmias is often necessary in acutely ill cardiac patients. The electrical current may cause elevation of biochemical markers used to diagnose acute myocardial infarct ion. Therefore it is important to find cardiac markers with high specificit y for myocardial necrosis. The purpose of this study was to assess the effe cts of elective cardioversion of atrial fibrillation or flutter on troponin T and I among conventional markers in patients with no evidence of acute i schemia. Methods and Results Fifty-seven consecutive patients underwent 1 to 4 direc t current shocks (mean cumulative energy 407 J, range 100 to 920 J) under g eneral anesthesia. At baseline, all had normal troponin levels; 50 patients (mean age 68 years, range 33 to 84 years) had normal cardiac enzymes and w ere included in the final analysis. Blood samples were drawn at baseline, a nd 1 to 2, 6 to 8, and 20 to 24 hours after cardioversion. The troponin lev els were unaffected by cardioversion in all patients, whereas creatine kina se and myoglobin increased more than 10-fold. Creatine kinase MB moss and a spartate aminotransferase were above reference limits in 18% and 24% of pat ients, respectively, 20 to 24 hours after cardioversion. There was a signif icant association between elevated creatine kinase, myoglobin, and creatine kinase MB levels with cumulated energy delivered as well as when possible confounders such as age and sex were adjusted for. High international norma lized ratio with warfarin use was associated with increased levels of creat ine kinase, aspartate aminotransferase, lactate dehydrogenase, and myoglobi n. Conclusions The increase of conventional biochemical markers after direct c urrent cardioversion is positively associated with cumulative energy delive red and international normalized ratio (INR) valves; neither influences lev els of the cardiac troponins.