Improved detection of radiofrequency current-induced minor myocardial injury by cardiac troponin T measurement.
Transcatheter radiofrequency current application in patients with cardiac arrhythmias was reported to be associated with a low rate of an increase in the activity of enzyme creatine kinase (CK) and CK-MB isoenzyme. As the novel heart-specific protein troponin T (cTnT) was shown to be superior to CK and CK-MB in detecting small damage to myocardial tissue in various clinical situations including unstable angina, a comparison of the diagnostic efficiency of these marker proteins to detect myocardial damage was made in 34 patients (mean age 38.3 +/- 15.6 years) undergoing radiofrequency (RF) catheter ablation of accessory pathways (n = 17) and atrioventricular nodal reentrant tachycardia (n = 17). Serial measurements of total CK and CK-MB activity before and every 8 hours for 24 hours after ablative procedure were performed with enzymatic and immunoinhibition method, respectively, using automated chemical analyzer Hitachi 717. Serum concentration of cTnT was determined by one-step sandwich ELISA performed on ES 300 analyzer (Boehringer Mannheim). With a median of 7.0 (range 1-39) RF current pulses only 12 (35%) and 10 (29%) of 34 patients showed an increase above the upper limit of normal CK and CK-MB activity, respectively. The peak activity of CK (mean peak = 285.8 +/- 517.7 IU/L) occurred at a variable time that infrequently coincided with those of peak CK-MB activity (23.1 +/- 8.0 IU/L). By contrast, all except 4 (88%) of 34 patients exhibited a distinct elevation of cTnT concentration (mean peak = 0.56 +/- 0.63 ng/ml), with almost all (33) of these 34 patients showed an early peak value at 8 hours postprocedural. There was, on the average, a small but distinct higher relative increase (5.6 times) in cTnT concentration from the upper limit of reference range compared with those of CK (1.5 times) and CK-MB peak activity (0.9 time). In conclusion, cTnT exhibited a minor but distinct elevation in its concentration and demonstrated a higher rate and magnitude of increase following radiofrequency current application than the conventional CK and CK-MB isoenzyme. Measurements of cTnT serum concentration may thus provide a useful test method for assessing the effect of the new transcatheter ablation procedures on myocardial tissue.
Department of Clinical Pathology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
K
K
Sribhen
K
K
Bhuripanyo
O
O
Raungratanaamporn
S
S
Kiartivich
W
W
Leowattana
S
S
Chaithiraphan
D000328:Adult; D000704:Analysis of Variance; D017115:Catheter Ablation / Q000009:adverse effects* / Q000379:methods; D003402:Creatine Kinase / Q000032:analysis / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006335:Heart Injuries / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D007527:Isoenzymes; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D011184:Postoperative Period; D011846:Radio Waves / Q000009:adverse effects; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000201:enzymology / Q000601:surgery*; D020107:Troponin T / Q000032:analysis*
D007527:Isoenzymes; D020107:Troponin T; D003402:Creatine Kinase