Incisional atrial reentrant tachycardias are macroreentrant arrhythmias in which surgical scars or prosthetic material constitute one of the constraining barriers of the circuit. Accurate reconstruction based on fluoroscopy-guided endocardial mapping of the reentrant circuit is often incomplete and time consuming explaining, at least in part, the modest long-term results of this technique. Mapping and ablation of these arrhythmias using a three-dimensional nonfluoroscopic mapping system that allows electroanatomic reconstruction of the reentrant circuit could help in identifying the ablation targets and improve long-term outcome. The study included 20 patients (12 men, mean age 45+/-18 years) with corrected congenital heart disease (4 patients), coronary artery bypass surgery (7 patients), mitral or aortic valve replacement or reconstruction (6 patients), valve replacement and coronary revascularization (2 patients), and mitral valve replacement with maze procedure for atrial fibrillation (1 patient). Endocardial mapping with this novel system was complemented by standard electrophysiological techniques used to identify a critical isthmus of conduction. Two or more nonconductive areas of atrial tissue or surgical prosthetic material delimiting a critical isthmus of conduction were identified in every patient. Radiofrequency linear applications spanning two to more boundaries successfully eliminated the tachycardia in every patient. At a follow-up of 11.5+/-5.1 months (range 17-5 months), two (10%) patients developed a new clinical arrhythmia. The remaining 18 had no recurrences off medical therapy. Mean fluoroscopy time was 45.7+/-15.2 minutes for patients with a single scar and 89+/-41.2 minutes in patients with two or more scars. In conclusions, this new nonfluoroscopic mapping system offers the opportunity to achieve a high rate of cure of complex macroreentrant atrial tachycardias by facilitating reconstruction of the macroreentrant circuit and its boundaries.