The catheter ablation of cardiac arrhythmias causes myocardial destruction and increase of the cardiac troponin and C-reactive protein (CRP). Data regarding dynamics of high-sensitivity troponin during irrigated ablation are scarce, and for diagnostic electrophysiological studies (EPS) are lacking. We aimed to study the periprocedural dynamics of high-sensitivity cardiac troponin I (hscTn I) and CRP, as well as their relation to different procedural parameters during EPS and ablation of various arrhythmias. Material and methods: Consecutive patients with EPS or ablation performed were studied prospectively. Clinical and procedural characteristics, and pre- and postprocedural values of hscTn I and CRP are presented at days 1, 2 and 3. Six indices were chosen as procedural markers of induced myocardial injury. P-value < 0.05 was accepted as statistically signifi cant for all tests performed. Results: Eight EPS and 98 ablations were performed in 103 patients (58 males, 56.3%). For ablations the baseline values of hscTn I at day 1 were 3.2 ng/L (1.7-4.93), while postprocedural values at days 2 and 3 were 500 ng/L (269-1044) and 404 ng/L (179-1017), р < 0.05 for all days. Postprocedural hscTn I values were moderately to strongly correlated to radiofrequency (RF) energy, time and number of RF applications. Postprocedural increase of CRP was also significant, but its magnitude was much smaller. Its correlation to procedural indices was weak. For EPS the baseline values of hscTn I were 5.95 ± 5.34 ng/L (0.6-15.9), while for the next 2 days these were 53.2 ± 43.1 ng/L (13.3-144) и 16.7 ± 9.65 ng/L (3.3-30.9), р < 0.05 for all days. Conclusion: Signifi cant postprocedural increase of hscTn I was detected in all electrophysiology procedures – EPS and ablations. This increase was more pronounced and prolonged to at least the next day after ablation. It was clearly correlated to the cumulative RF energy, RF time and number of RF applications. Early increase of CRP was also signifi cant, but to a lesser magnitude and in weak correlation to the procedural parameters.