Author + information
- Received November 22, 1995
- Revision received March 6, 1996
- Accepted March 9, 1996
- Published online August 1, 1996.
- Gust H. Bardy, MD, FACCa,*,
- Raymond Yee, MD, FACC*,
- Werner Jung, MD†,
- for The Active Can Investigators
- ↵*Address for correspondence: Dr. Gust H. Bardy, Department of Medicine, Division of Cardiology, Box 356422, University of Washington Medical Center, Seattle, Washington 98195-6422.
Objectives. The purpose of this study was to prospectively examine in a multicenter study the methods of use, efficacy and complications of a unipolar cardioverter-defibrillator in patients at risk for sudden cardiac death.
Background. Implantation of cardioverter-defibrillators in the pectoral region offers a significant opportunity to improve the management of patients with life-threatening arrhythmias. Unipolar, single-lead, pectoral implantable cardioverterdefibrillators might decrease related mortality, morbidity and costs in the care of such patients.
Methods. From November 3, 1993 to May 8, 1995, a unipolar defibrillator (Medtronic model 7219C) was selected for use in 473 patients from 74 centers (386 [82%] men, 87 [18%] women; mean [±sd]age 59 ± 13 years, range 16 to 88). The clinical indication for use was ventricular fibrillation in 157 patients, sustained ventricular tachycardia in 236, both ventricular tachycardia and ventricular fibrillation in 53 and syncope or inducible ventricular tachycardia/ventricular fibrillation in 27. Coronary artery disease was present in 323 patients (68%). The mean left ventricular ejection fraction was 0.36 ± 0.15 (range 0.10 to 0.85). The distribution of New York Heart Association congestive heart failure was class I = 34%; class II = 45%; class III = 17%; and class IV = 2%.
Results. The unipolar cardioverter-defibrillator was inserted successfully in 464 (98%) of 473 candidates. Effective defibrillation occurred with the first shock polarity tested in 88% of patients, after a polarity switch in 8% and after lead or generator repositioning in 2%. The stored energy defibrillation threshold was obtained at implantation in 339 patients (72%) and was 11.5 ± 6.1 J, with 72% of patients having a defibrillation threshold ≤12 J. The mean “skin-to-skin” implantation time was 96 ± 45 min (range 25 to 335 min). Complications occurred in 29 patients (6%). Device therapy for 2,160 spontaneous ventricular tachycardia or fibrillation episodes occurred in 128 patients (27%) over a 2,732 device-month experience (range 0 to 17.2) and was effective in 98.7% of episodes. There were 14 deaths (10 nonsudden cardiac, 3 sudden cardiac, 1 noncardiac). Cumulative survival, on an intention-to-treat basis from all causes of death at 17.2 months, was 94.4%.
Conclusions. Unipolar pectoral implantable cardioverterdefibrillators can be inserted with a high likelihood of success in a relatively brief procedure. Defibrillation thresholds are low, morbidity is modest, and survival rates are good with this new type of implantable cardioverter-defibrillator.
A complete list of the Active Can Investigators appears in the Appendix. This work was supported in part by Medtronic Inc., Minneapolis, Minnesota. Drs. Bardy and Yee have been consultants for Medtronic, Inc., Minneapolis, Minnesota, on implantable defibrillator therapy and sudden death.
All editorial decisions for this article, including selection of referees, were made by a Guest Editor. This policy applies to all articles with authors from the University of California San Francisco.
- Received November 22, 1995.
- Revision received March 6, 1996.
- Accepted March 9, 1996.
- American College of Cardiology