Abstract 16773: Exercise Tolerance and Vo2 Are Improved in Patients Undergoing Fontan Conversion with Arrhythmia Surgery

Abstract

Background: Exercise tolerance in Fontan patients is known to decline with advancing age. The impact of improving right atrial flow dynamics and eliminating anti-arrhythmic medications on exercise tolerance is not known. Hypothesis: Successful Fontan conversion with arrhythmia surgery results in improvement in exercise tolerance over time. Methods: We reviewed data on patients who underwent Fontan conversion at our center since 1994. Fontan conversion surgery included arrhythmia surgery with pacemaker implantation. Exercise duration, peak HR, respiratory quotient, VO2, age at most recent exercise test and postoperative interval were recorded. Continuous variables were compared using two-tailed t-test method. Results: Fontan conversion with arrhythmia surgery has been performed on 132 pts at our institution. Pre-operative exercise testing was performed in 88 pts, with paired follow-up exercise data available on 29 pts. The mean age at Fontan conversion was 22.7 years. The mean interval from surgery to the most recent exercise stress test was 4.8 years (0.5-14.1 yrs). The mean exercise duration at baseline was 69% predicted for age and improved to a mean of 78% predicted for age at follow-up (p=0.02, mean duration in minutes: 6.9 at baseline, 8 at follow-up). The mean VO2 predicted for age improved from 53% to 64% (p<0.01, mean VO2 in ml/kg/min increased from 22.3 to 25.8) (see graph below for results). No significant change was seen in peak heart rate (148 vs 150 bpm, p=NS). Conclusions: In contrast to an expected decline in exercise tolerance with age in Fontan patients, successful Fontan conversion with arrhythmia surgery results in improvement in exercise endurance and oxygen consumption over a 5 yr follow-up period. Data was only available in a limited subset of patients undergoing Fontan conversion. These findings suggest that aggressive measures to improve hemodynamics in Fontan patients can result in improvement in functional status in adulthood.