Cardiac troponin I does not increase after cardioversion.

BACKGROUND

Serum total creatine kinase (total CK) level increases in the patients following electrical cardioversion. The same has been observed with CK-MB, an isoenzyme of the total CK with some cardiospecificity. Cardiac troponin I (cTnI), a new specific cardiac biological marker, is highly effective to discriminate myocardial and muscular injuries after noncardiac surgery.

METHODS

To assess cardiac damage after cardioversion, we measured serum cTnI, myoglobin, total CK, CK-MB mass, 1, 2, 3, 4, 8, 12, and 24 h after elective cardioversion of supraventricular tachycardia in 28 patients (eight women, 20 men; mean age, 64 +/- 10 years). Cumulative energy was below 370 J in 17 patients, between 370 and 900 J in eight patients, and 1,020 J in three patients. Serum cTnI was measured using a sandwich immunoenzymologic assay. The detection limit of the assay was 0.35 microgram/L and normal values range from 0.35 to 1.3 micrograms/L.

RESULTS

In all but three patients, cTnI remained below 0.35 microgram/L. In these three patients, cTnI ranged between 0.35 and 0.9 microgram/L. There was no correlation between cTnI and the number or the energy of cardioversion. Myoglobin and total CK increased to abnormal concentrations in 11 patients (myoglobin, 630 +/- 190 micrograms/L, and total CK, 2,584 +/- 780 U/L) and reached myocardial infarction-like values in five patients. Modest increases of CK-MB were then also observed. A strong correlation was observed between the total energy of direct current cardioversion and the increase of either myoglobin (r = 0.87; p < 001) or total CK (r = 0.81; p < 001).

CONCLUSION

Cardioversion in a clinical setting does not induce elevation of cTnI. Increase in total CK, CK-MB, and myoglobin may be due solely to muscular lesions and is closely related to the cumulative energy delivered.