[Myoglobin and troponin I as markers of myocardial damage during cardioversion of atrial fibrillation].

UNLABELLED

We performed direct comparison of safety and efficacy of monophasic and biphasic shock cardioversion (CV) of atrial fibrillation (AF). Troponin I (cTnl) and myoglobin (My) were used as markers of potential myocardial and skeletal muscle damage during the procedure.

METHODS

63 patients (p.t.s.) with persistent, nonvalvular AF (F/M 18/45; mean age 61.6 +/- 11.4 years) were randomized to CV either with monophasic (F/M 10/24, Group I) or biphasic (F/M 8/21, Group II) shock. Plasma levels of cTnl and My were measured before CV, 6 hours and 24 hours after CV.

RESULTS

The efficacy of CV was significantly higher in Group II (93% vs 85%, p < 0.04). Sinus rhythm restoration required lower total energy used during procedure with biphasic shock (379.8 +/- 301.5 vs 192.8 +/- 100.6 J; p 0.001). There was no significant difference in mean values of cTnl before CV in both groups (0.3 +/- 0.2 vs 0.2 +/- 0.1 ng/mL, p > 0.15). In 14 pts (41%) from Group I and 3 pts (10%) from Group II plasma cTnl concentration above discriminatory level (0.9 ng/mL) were noted. There was a significant increase in mean plasma cTnl level (0.3 +/- 0.2 vs 1.9 +/- 0.9 ng/mL, p < 0.04) 24 hours after the procedure in Group I. We did not observed significant differences in cTnl plasma concentration 6 and 24 hours after CV in Group II (0.2 +/- 0.1 vs 0.4 +/- 0.2 ng/mL, p > 0.15). Both study groups did not significantly differ in mean serum My level at baseline (39.1 +/- 14.2 vs 43.1 +/- 20.9 ng/mL). In Group I mean My serum concentration increased during the first 6 hours after CV (43.1 +/- 20.9 vs 247.9 +/- 53.3 ng/mL, p < 0.02) and there was a significant decreasing in My serum level during the further observation (247.9 +/- 53.3 vs 104.5 +/- 46.1 ng/mL, p < 0.03). Mean serum My concentration remained within normal ranges during the 24 hour follow-up after the biphasic shock CV (43.1 +/- 20.9 vs 43.6 +/- 29.1 ng/mL). Increased of cTnl and My in Group I may be due to myocardial and skeletal muscle damage and correlate closely with cumulative energy delivered (Spearmann correlation index (r) = 0.55, p < 0.01 for My and r = 0.66, p < 0.01 for cTnl). In Group I positive correlation between cumulative energy used during CV and increase of studied markers indexed with left ventricular mass (r = 0.6, p < 0.05 for My and r = 0.74, p < 0.04 for cTnl) was observed. There was no significant correlation between delivered energy and increase of heart markers in Group II noted.

CONCLUSIONS

We observed the significant increase in mean serum cTnl and My level 24 hours after CV with monophasic shock and its positive correlation with total energy used during the procedure. There is a conclusion that biphasic shock used during CV of AF is more efficient and may cause less myocardial and skeletal muscle damage due to lower energy delivered.