Thrombogenicity of radiofrequency lesions: results with serial D-dimer determinations

By measuring plasma levels of D-dimer, a product of fibrin degradation, we sought to investigate whether the application of radiofrequency (RF) energy might activate endogenous thrombotic mechanisms.

Quantitative determination of D-dimer, a bio-chemical marker of thrombus formation and reactive fibrinolysis, helps to diagnose activation of the coagulation system. It remains controversial whether endocardial lesions produced during RF catheter ablation of arrhythmogenic foci have a thrombogenic effect, and the issue of the need for antithrombotic therapy after RF ablation is still unresolved.

We made serial determinations of plasma D-dimer levels by enzyme immunoassay before insertion of catheters, after completion of electrophysiologic study (EPS) but before RF ablation, immediately after RF ablation and before discharge (at 48 h) from the hospital in 37 patients undergoing RF ablation (22 men, 15 women; mean [+/-SD] age 37 +/- 18 years, range 12 to 74; 16 +/- 16 lesions produced) of accessory (n = 17) or slow (n = 12) pathways, atrial (n = 4) or ventricular foci (n = 3) or the atrioventricular node (n = 1). D-dimer levels were also measured in 26 age-matched control subjects undergoing EPS only.

In the RF ablation group, the mean D-dimer levels increased from a baseline value of 29 +/- 28 to 62 +/- 56 micrograms/liter after EPS (p < 0.0001). However, after RF ablation, D-dimer levels increased to much higher levels (188 +/- 138 micrograms/liter, p < 0.0001). There was no correlation of D-dimer levels with the number of RF lesions produced or the duration of the procedure. At 48 h after the procedure, D-dimer levels decreased (75 +/- 67 micrograms/liter) but still remained significantly elevated compared with baseline values (p = 0.0001). Three were no significant differences in baseline (25 +/- 21 micrograms/liter) and post-EPS (51 +/- 50 micrograms/liter) measurements between control subjects and patients. During RF ablation, intravenous heparin was given to nine patients who still demonstrated high plasma D-dimer levels after RF ablation.

As reflected by elevated plasma D-dimer levels, RF ablation has a thrombogenic effect that persists through 48 h after the procedure. This effect needs to be taken into account when considering antithrombotic therapy in patients undergoing RF ablation.