Randomized Comparison of Bipolar versus Unipolar Plus Bipolar Recordings During Segmental Ostial Ablation of Pulmonary Veins HIROSHI TADA, M.D., HAKAN ORAL, M.D., BRADLEY P. KNIGHT, M.D., MEHMET OZAYDIN, M.D., AMAN CHUGH, M.D., CHRISTOPH SCHARF, M.D., SOHAIL HASSAN, M.D., RADMIRA GREENSTEIN, M.D., FRANK PELOSI, JR., M.D., S. ADAM STRICKBERGER, M.D., and FRED MORADY, M.D. From the Division of Cardiology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan Unipolar vs Bipolar Electrograms. Introduction: Segmental ostial ablation to isolate pulmonary veins is guided by pulmonary vein potentials. The aim of this prospective randomized study was to compare the utility of unipolar plus bipolar electrograms versus only bipolar electrograms as a guide for segmental ablation to isolate the pulmonary veins in patients with atrial brillation. Methods and Results: Isolation of the left superior, right superior, and left inferior pulmonary veins was attempted in 44 patients (35 men and 9 women; mean age 54 6 10 years) with paroxysmal atrial brillation. A decapolar Lasso catheter was positioned in the pulmonary veins, near the ostium, and a conventional ablation catheter was used for segmental ablation aimed at elimination of all pulmonary vein potentials. One hundred fourteen pulmonary veins were randomly assigned for ostial ablation guided by either bipolar or unipolar plus bipolar recordings. Electrical isolation was achieved in 51 (96%) of 53 pulmonary veins randomized to the bipolar approach, and 57 (93%) of 61 pulmonary veins randomized to the unipolar plus bipolar approach (P 5 0.7). In the unipolar plus bipolar group, the total duration of radiofrequency energy needed to achieve isolation, 5.5 6 2.8 minutes/vein, was signicant shorter than in the bipolar group, 7.6 6 4.1 minutes/vein (P < 0.01). Mean procedure and uoroscopy durations per vein were 19% to 28% shorter in the unipolar plus bipolar group. Conclusion: Segmental ostial ablation to isolate the pulmonary veins can be achieved more efciently and with less radiofrequency energy when guided by both unipolar and bipolar recordings than by bipolar recordings alone. (J Cardiovasc Electrophysiol, Vol. 13, pp. 851-856, September 2002) atrial brillation, pulmonary vein, unipolar electrogram Introduction Segmental ablation to isolate the pulmonary veins is guided by pulmonary vein potentials recorded near the ostia of the pulmonary veins. 1-5 By post hoc analysis, a recent study indicated that unipolar electrograms may provide better discrimination between successful and unsuccessful ostial ablation sites than bipolar electrograms. 6 The aim of this prospective randomized study was to compare the util- ity of unipolar and bipolar electrograms as a guide for segmental ablation to isolate the pulmonary veins in patients with atrial brillation. Methods Patient Characteristics The subjects of this study were 44 patients with drug- refractory, paroxysmal atrial brillation who underwent segmental ostial ablation to isolate the pulmonary veins. There were 35 men and 9 women (mean age 54 6 10 years). Mean duration of symptomatic atrial brillation was 8.5 6 7.8 years, and mean number of symptomatic episodes per month was 13 6 11. One patient had coronary artery disease, and the remaining 43 patients had no structural heart disease. Echocardiography demonstrated a mean left ventricular ejection fraction of 0.62 6 0.09 and a mean left atrial diameter of 39 6 4 mm. Study Protocol The study protocol was approved by the Institutional Review Board. Therapy with antiarrhythmic drugs was dis- continued at least 48 hours before the procedure. In the case of amiodarone, therapy was discontinued at least 6 weeks before the procedure. After obtaining informed consent, a quadripolar electrode catheter was inserted into a femoral vein and positioned in the coronary sinus. Transseptal cath- eterization was performed and selective pulmonary venous angiograms were performed to identify the location of the ostia. A 7-French decapolar ring catheter with 1-mm elec- trodes spaced at intervals of 4.5 or 6.0 mm (Lasso TM ; Biosense Webster, Diamond Bar, CA, USA) and a 7-French quadripolar ablation catheter with a 4-mm distal electrode, an embedded thermistor, interelectrode spacing of 2-5-2 mm, and a deectable tip (EP Technologies, San Jose, CA, USA) were inserted into the left atrium. Heparin was ad- ministered as needed to maintain an activated clotting time Supported in part by a grant from the Gunma Prefecture Government and the Ellen and Robert Thompson Atrial Fibrillation Research Fund. Address for correspondence: Fred Morady, M.D., Division of Cardiology, Department of Internal Medicine, University of Michigan, 1500 E. Medical Center Drive, B1F245, Ann Arbor, MI 48109-0022. Fax: 734-936-7026; E-mail: fmorady@umich.edu Manuscript received 5 April 2002; Accepted for publication 3 July 2002. 851 Reprinted with permission from JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Volume 13, No. 9, September 2002 Copyright ©2002 by Futura Publishing Company, Inc., Armonk, NY 10504-0418