We have developed this special issue of the Journal based on the presentations at the 4th International Symposium on Interventional Electrophysiology in the Management of Cardiac Arrhythmias held in Newport, Rhode Island in September 26–28, 2003. These meetings have pioneered and helped define a distinct discipline of Interventional Cardiac Electrophysiology since their inception in 1990, when it became the first international symposium to address this subject. This occurred at a time when it lacked an identity and definitive content. Since then, it has become a quadrennial review of the state of the art in Interventional Electrophysiology from basic science developments to new techniques and technology in this arena. This meeting was endorsed or co-sponsored by the North American Society of Pacing and Electrophysiology, the European Society of Cardiology, The Electrophysiology Research Foundation and the Atlantic Health System of New Jersey and the University of Bonn, Germany. The symposium brought together recognized international experts in this field from Europe, Asia and the United States to undertake a critical analysis of the current developments and examine future directions in cardiac rhythm management. The last compendium of review articles from the prior discussions were published in 2000 when we asked participants to address pivotal questions at the turn of the millennium. Since that occasion, there have been important advances in fundamental concepts in molecular and experimental electrophysiology, pharmacotherapy and device therapy, hybrid therapies, new technologies for mapping and ablation, sudden cardiac death prevention, evolution of new directions in atrial fibrillation management, and new applications of device therapy in heart failure and syncope. All in all, these developments have culminated in major advances in therapeutics in cardiac rhythm management. These new frontiers have been addressed and examined in these reviews. Since its inception in 1995, the Journal has attempted to provide its readers and researchers in cardiac arrhythmias with a blend of cutting edge original research and periodic review of new developments. This double issue follows this track faithfully and we hope this will provide students of this field with an important new addition to their library of information. This issue of the Journal has undergone standard peer review mechanisms and we hope it will provide insights into the future of this extraordinarily prolific and rapidly developing scientific field. We are deeply grateful to Ms. Melissa Ramondetta and Ms. Diane Wuori at Kluwer Academic Publishers and Ms. Celeste Simmons at the Electrophysiology Research Foundation who have helped make this volume a reality. Finally, we remain, as always, indebted to the faculty who authored the contributions to this issue and whose efforts can only in some modest measure be recompensed by the final product and its contribution to this field.