The potential usage of dual chamber pacing in patients with implantable cardioverter defibrillators

Bradycardia support by ICDs has been limited to fixed rate, ventricular pac ing. Concomitant placement of a pacemaker and an ICD exposes a patient to p otentially life-threatening device interactions. ICDs capable of dual chamb er pacing have recently become available. The number of ICD recipients who stand to benefit from the addition of dual chamber pacing is debated, but n o data have addressed this question. This retrospective study analyzed all patients who received nonthoractomy ICD system placement at the Mayo Clinic in Rochester, MN between March 1991 and October 1996 in order to determine the proportion of patients in whom a dual chamber pacing ICD may be indica ted. Definitions: (1) Definitely indicated. = pacemaker present at ICD impl ant or NASPE Class I pacing indication; (2) Probably indicated = NASPE Clas s II pacing indication, NYHA Functional Class III or IV, or history of syst olic congestive heart failure; (3) Possibly indicated = history of paroxysm al atrial fibrillation or an ejection fraction less than or equal to 20%. T he results were that nonthoracotomy ICDs were placed in 253 patients. A dua l chamber ICD would have been definitely indicated in 11% of the study grou p, probably indicated in 28%, and possibly indicated in 14%. Chronic atrial fibrillation was present at ICD implant in 6.7% of patients and developed in 0.9%/yr during follow-up. The addition of dual chamber pacing to ICDs st ands to potentially benefit approximately half (53%) of ICD recipients. The se data do not address all patients who may benefit from dual chamber sensi ng.