THE EVOLUTION OF PLATELET AGGREGABILITY IN PATIENTS UNDERGOING CATHETER ABLATION FOR SUPRAVENTRICULAR TACHYCARDIA WITH RADIOFREQUENCY ENERGY - THE ROLE OF ANTIPLATELET THERAPY

Forty-two consecutive patients were checked for profiles of platelet a ggregability before, during, and 10 and 30 minutes after catheter abla tion. They were randomized into Group A (n = 20) who accepted intraven ous aspirin (in 0.015 g/kg body weight) and Group P (n = 22) who accep ted only placebo treatment. Blood samples were drawn from ascending ao rta (Ao) and main pulmonary artery (MPA) simultaneously at each time p eriod. In Group P, the EC(50) of substrate induced platelet aggregabil ity decreases significantly during (for ADP, from 1.72 to 0.78 mu umol /L for samples from Ao, P < 0.0001; and from 1.68 to 0.69 mu mol/L for MPA, P < 0.0001; for collagen, from 2.26 to 1.34 mu g/mL for Ao, P < 0.005, and from 2.40 to 1.64 mu g/mL, P < 0.0001) and 10 minutes after successful ablation (for ADP, to 0.70 mu mol/L for Ao, P < 0.000, and to 0.61 mu mol/L for MPA, P < 0.0001; for collagen, to 1.54 mu g/mL f or Ao, P < 0.01, and to 1.63 mu g/mL, P < 0.0001), and then returned t o baseline levels 30 minutes later (all P = NS) compared with comparat ive baseline levels. The levels of thromboxane B2 (TXB2) had the simil ar evolution. The evolution of platelet aggregability profiles was not associated with fetal energy dose, duration of energy application, du ration of procedure, impedance, and ablation site. However, there were moderate positive correlations between the TXB2 levels and tip temper atures (r = 0.56, p < 0.05 for Ao and r = 0.85, P < 0.01 for MPA). The se results suggest that increased platelet aggregability can occur dur ing and 10 minutes after radiofrequency current ablation and antiplate let therapy can maintain ''flat'' response of platelet aggregability t o radiofrequency energy, which may provide possible benefits in preven ting the occurrence of the complication.