Dual-chamber (DDD) pacing mode survival was assessed by reviewing 486 consecutive initial transvenous DDD pacemaker implantations between December 1981 and December 1988 inclusive, with a mean follow-up time of 33 months. The patients' mean age was 71.4 years and 55% were male; 38% had dominant sinoatrial and 62% had dominant atrioventricular (AV) node disease. Nineteen patients (4%) underwent secondary operative intervention for lead dislodgement (n = 11), lead or pulse generator malfunction (n = 6) or infection (n = 2). During follow-up, 87 patients (18%) had their device permanently reprogrammed out of the DDD mode and 10 others (2%) required temporary reprogramming out of this mode; 12 patients who required device reprogramming were managed in other dual-chamber or atrial pacing modes. Reasons for reprogramming included atrial fibrillation (n = 48; 10%); loss of atrial sensing (n = 26; 5%); recurrent "endless loop" tachycardia (n = 5; 1%); lead dislodgement without repositioning (n = 4; 1%); pulse generator malfunction (n = 1; 1%) and other (n = 5; 1%). The occurrence of atrial fibrillation was associated with dominant sinoatrial disease and a prior history of atrial fibrillation; 19% of atrial sensing loss was attributable to early or faulty pacemaker technology. The DDD mode survival rate at 1, 2, 3, 4 and 5 years was, respectively, 90%, 88%, 84%, 79% and 78%.(ABSTRACT TRUNCATED AT 250 WORDS)