Background : In a prospective study, we measured plasma markers of myocardial damage induced by radiofrequency catheter ablation (RFA) with the protein biochip microarray system. Methods : A total of 32 consecutive patients undergoing RFA for atrioventricular nodal re-entry tachycardia (AVNRT), right atrial flutter (AFL) and atrial fibrillation (AF) were included in the study. Cardiac troponin I (cTnI), creatine kinase isoenzyme MB (CK-MB), heart-type fatty acid binding protein (hFABP) and glycogen phosphorylase BB (GPBB) were measured using biochip array technology at baseline and 24 h after the procedure. Results : Values for all markers increased 24 h after RFA (cTnI: 0.92±0.49 μg/L vs. 0.33±0.06 μg/L, p<0.001; CK-MB: 3.79±2.04 μg/L vs. 1.85±0.55 μg/L, p<0.001; hFABP: 2.82±0.95 μg/L vs. 2.00±0.95 μg/L, p<0.001; GPBB: 9.07±5.83 μg/L vs. 4.70±2.50 μg/L, p<0.001). The correlations between plasma marker levels and RFA time were cTnI: r=0.63, p<0.01; CK-MB: r=0.75, p<0.01; hFABP: r=0.55, p<0.05, GPBB: r=0.51, p<0.05; the correlation between RFA time and number of RF applications was significant (r=0.81, p<0.001). Patients with RFA due to AF or flutter had elevated cTnI, CK-MB and hFABP levels compared to patients with AVNRT (cTnI: 1.14± 0.49 μg/L vs. 0.59±0.25 μg/L, p<0.05; CK-MB: 4.46± 2.07 μg/L vs. 2.81±1.54 μg/L, p<0.05; hFABP: 3.21± 0.98 μg/L vs. 2.25±0.54 μg/L, p<0.01). Conclusions : Myocardial injury induced by RFA can be detected by cTnI, CK-MB, hFABP and GPBB. Plasma cTnI, CK-MB and hFABP levels significantly increased in patients with AFL and AF compared to patients with AVNRT. The increase of cTnI, CK-MB and GPBB levels correlates with the total duration of RFA. Clin Chem Lab Med 2008;46:1726–8.