Objective One major principle limitation of conventional RFCA continues to be the risk of thromboembolism.Our study was performed to investigate the incidence and risk factors of VTE in patients undergoing EPS and RFCA.Methods A prospective study was conducted from February 2003 to August 2006 in our clinic.A total of 348 patients with EPS (n=231) and RFCA (n=117) were analyzed.For the diagnosis of DVT, Duplex ultrasonography evaluation of the bilateral femoral veins was performed after the procedure.Lung ventilation/perfusion scintigraphy was carried out in patients suspected to have PTE.An initial bolus of 3000 IU heparin was injected to all patients, and additional heparin was supplied when the activated clotting time (ACT) was less than 300 sec during the procedure.