Cardiac troponin I does not increase after cardioversion

Abstract

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 μg/L and normal values range from 0.35 to 1.3 μg/L. Results: In all but three patients, cTnI remained below 0.35 μg/L. In these three patients, cTnI ranged between 0.35 and 0.9 μg/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 μg/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.