EFFECT OF DC SHOCK ON SERUM LEVELS OF TOTAL CREATINE-KINASE, MB-CREATINE KINASE MASS AND TROPONIN-T

After successful resuscitation from cardiac arrest, it is important to identify whether the event has been triggered by a myocardial infarct ion, since this determines subsequent investigations and management. P revious studies have shown that biochemical indices of infarction beco me elevated after resuscitation in patients without myocardial infarct ion. This can lead to overdiagnosis of myocardial infarction in the po st-arrest setting. The cause of the elevated enzyme levels is not know n, but may involve electrical or mechanical injury to the heart during resuscitation. In this study we aimed to identify the effects of isol ated direct current shock on serum levels of creatine kinase (CK), MB creatine kinase mass (MB-CK), and troponin T, and examined the relatio nships between enzyme levels and the dose of electrical energy used. T hirteen patients were studied who underwent DC cardioversion for atria l fibrillation. Serum was obtained for CK, MB-CK and troponin T estima tion before and 10 min after cardioversion, at hourly intervals for 8 h, and 18 h after cardioversion. Total serum CK became significantly e levated after only 3 h and rose to a peak of 1294.4 IU l(-1) (P < 0.02 ) at 18 h. Post-shuck CK levels were strongly correlated with total sh ock energy (r = 0.8, P < 0.01). Serum MB-CK was significantly elevated at 18 h among patients receiving total shock energies greater than 10 00 J than in those receiving lower doses, reflecting a positive correl ation (r = 0.64, P < 0.05) between shock energy and peak MB-CK level. Troponin T levels were not significantly elevated after cardioversion. In conclusion, total serum CK levels become significantly elevated ea rly after cardioversion, suggesting rapid wash-out from injured skelet al muscle. MB-CK levels become significantly elevated in individuals r eceiving high energy shocks, probably due to release of small quantiti es of the CK-MB isoform from skeletal muscle. The negligible troponin T levels seen after high energy cardioversion indicate that significan t myocardial injury does not occur. Electrical injury is not likely to account for the elevated troponin T levels seen after out-of-hospital resuscitation in patients without myocardial infarction. (C) 1998 Els evier Science Ireland Ltd. All rights reserved.