Commemorating twenty years since the first catheter-based pulmonary vein isolation to treat atrial fibrillation by ablation.

Surgical pulmonary vein isolation by ablation as a treatment for atrial fibrillation was first performed in isolation in 1996 at Hospital de Santa Cruz in Portugal, as a complementary therapy to mitral valve surgery in patients with rheumatic mitral valve disease, in order to reduce the morbidity associated with maze surgery. This innovative surgical approach, performed by Queiroz e Melo, replaced the maze technique’s fragmentation of the atria using surgical incisions by application of radiofrequency energy along the pulmonary veins. Its efficacy was assessed by electrophysiological studies that showed bilateral pulmonary vein isolation and it reduced postoperative morbidity. The surgical procedure reproduced a preliminary study in sheep by Fieguth et al., which showed that atrial fibrillation was not inducible following surgical isolation of the pulmonary veins. In 1996, having confirmed the efficacy of surgical isolation and the feasibility of reproducing the same effect via catheter, we performed the first percutaneous procedure, in a patient with mitral stenosis and atrial fibrillation, at Hospital de Santa Cruz (Appendix A. Supplementary data). This patient was indicated for balloon mitral valvuloplasty due to rheumatic mitral valve stenosis, and after valve dilatation, using the same transseptal route, we isolated the pulmonary veins.