[Biochemical markers of myocardial damage after high-energy radiofrequency ablation of atrial flutter. Value of troponin I].

Creatinine phosphokinase and its MB iso-enzyme do not allow assessment of the degree of tissue necrosis after radiofrequency ablation. Cardiac Troponin I and myoglobin, new markers of myocardial lesions, are rarely used in this indication. The aim of this prospective study was to measure and compare serum markers of myocardial damage after high energy radiofrequency ablation of atrial flutter with an 8 mm distal electrode catheter. The authors measured serum cardiac Troponin I, myoglobin, creatinine phosphokinase and its MB iso-enzyme levels before and 4, 12 and 24 hours after radiofrequency ablation of common atrial flutter in 23 consecutive patients. The same markers were also measured in a control group of 9 patients undergoing electrophysiological investigation without radiofrequency ablation. All ablation procedures were simple with an average of 12.6 +/- 6 applications of radiofrequency. Bidirectional isthmic block was obtained in 22 of the 23 patients. The mean Troponin I levels were 0.01 microgram/l before ablation, 0.87 +/- 0.77 at the 4th hour (p < 0.001 versus control), 1.16 +/- 1.2 at the 12th hour (p < 0.001 versus control) and 0.7 +/- 0.63 microgram/l at the 24th hour (p < 001 versus control) after ablation. Only 13% of patients had cardiac troponin levels greater than the threshold of significant myocardial damage (> 2 micrograms/l) with a higher average number of radiofrequency applications than the rest of the group: 15.2 +/- 1 versus 11.5 +/- 5.1 (p < 0.05). An abnormally high level of markers was found in the ablation group for 19 patients (84%) with Troponin I (> 0.4 microgram/l), for 10 patients (43%) with the MB iso-enzyme (> 8 Ul/L), and for 1 patient (4%) with myoglobin (> 90 micrograms/l), and in no patient for creatinine phosphokinase (> 290 IU/L). All values were normal in the control group. The authors conclude that cardiac Troponin I is the most sensitive marker for myocardial cellular damage after high energy radiofrequency ablation of atrial flutter. The level of cardiac Troponin I seems to correlate with the number of applications of radiofrequency.