702-3 Factors Associated With Arrhythmias After Mustard Operation—30 Year Experience with 534 Patients

To determine factors associated with survival and arrhythmias, we reviewed 534 (359 males) consecutive patients after Mustard operation (MUST) for transposition of the great arteries (TGA) from 1963 to 1993. TGA was isolated for 354 pts, associated with VSD in 73, pulmonary obstruction (PS) in 50, VSD with PS in 46 and complex anomalies in 11. Median age at MUST was 16 months (range, 21 days to 19 yrs). There were 52 hospital deaths (9.7%). Late death occurred in 76 of 482 operative survivors (15.8%) with up to 31 years follow-up (mean 12.6±6.8 yrs). Late survival was 89% at 5 yr, 88% at 10 yr, 82% at 15 yr and 76% at 20 yr. Mode of late death included: Sudden, 39%; myocardial failure, 27%; pulmonary vascular disease, 10%; reoperation, 7%; pulmonary venous obstruction, 4%; non-cardiac, 4%; and other, 9%. Cox's proportional hazard modelling was used to assess independent factors associated with late death. Significant factors included: earlier date of operation (Odds Ratio, OR, 0.75 per 5 yrs). VSD closure at MUST (OR 2.5), and peri-operative atrial tachyarrhythmias at MUST (OR 1.9). Instantaneous risk (hazard) of late death declined, with a late peak and decline. Loss of sinus rhythmn (LSR) was noted in 29% of survivors: freedom from LSR was 82% at 5 yr, 67% at 10 yr, 60% at 15 yr and 52% at 20 yr. Significant independent factors associated with LSR included: pre-MUST surgical atrial septectomy (OR 1.7), peri-operative bradyarrhythmias (OR 1.7) and occurrence of atrial flutter (AFL) during follow-up. Instantaneous hazard of LSR showed a gradual decline after MUST with a second late peak. AFL was noted in 15% of survivors; freedom from AFL was 92% at 5 yr, 89% at 10 yr, 82% at 15 yr and 71% at 20 yr. Patients who were on digoxin vs. no medication at the time of their first AFL episode were less likely to have symptoms of presyncope or syncope (7% vs. 33%, P=0.06). Independent factors associated with late AFL included: LSR (OR 2.6) and peri-operative arrhythmias including AFL (OR 3.1). bradyarrhythmias (OR 2.5) and permanent heart block (OR 12.2). Instantaneous hazard of AFL showed a gradual incline with a late peak.