Randomization Patients who fulfilled the inclusion criteria will be immediately randomized to the two treatment groups by using consecutively numbered envelopes that contained the treatment assignments, which were generated by a computer-allocated random digit number, in a 1:1 ratio. Patients in the prophylactic group will receive antibiotic treatment right after randomization with intravenous cefazolin 2 g (3 g for patients weighing ≥120 kg) within 60 minutes before ablation therapy. Patients in the on-demand group will receive antibiotic therapy only when infection will be suspected or established. Antibiotics will be changed according to the antibiotic sensitivity test of cultured microorganisms.