The First Year Experience with the Dual Chamber ICD

In July 1997, a dual chamber pacemaker combined with a tiered therapy implantable cardioverter defibrillator (ICD) first became available in the United States. We report the first-year experience of one center in the United States with this dual chamber ICD. Of a total of 174 ICDs, 95 (55%) were dual chamber devices and 79 (45%) were single chamber. New dual chamber ICD insertions averaged 57.4 +/- 8.9 minutes, though there was a learning curve as the last 30 implants averaged 45.1 +/- 6.1 minutes with a negative slope to the regression line of procedure duration (-0.52, P < 0.05). New single chamber ICD implants were 18.5 minutes quicker (38.9 +/- 7.2 minutes). The most challenging implants were dual chamber upgrades (mean procedure duration 64.9 +/- 15.8 minutes), especially if there was a previously implanted pacemaker and ICD at separate sites. Indications for a new dual chamber device were grouped into classic pacemaker indications (52.5%), which comprised the Class I ACC/AHA guidelines, ICD-specific indications (24.6%), and other (23.0%). In the 34 patients undergoing dual chamber upgrade, the classic and ICD-specific groups were equal (47.0% each). Complications were rare (2.8%), though 3 (8.8%) of 34 undergoing a dual chamber upgrade developed late infections requiring explantation. In its first year, the dual chamber ICD has become a common device at our institution comprising 55% of new implants. As experience grows, we anticipate similar usage at most institutions.