Influence of ventricular morphology on aerobic exercise capacity in patients after the Fontan operation

OBJECTIVES This study investigated the influences of ventricular morphology , hemodynamics and clinical findings on exercise capacity in patients after the Fontan operation. BACKGROUND Determinants of exercise capacity after the Fontan operation rem ain unclear. METHODS Peak oxygen uptake (P(V) over dot O-2) was determined in 105 patien ts by exercise test and compared to hemodynamics and clinical findings. Pat ients were divided into three groups based on ventricular morphology: those with a right ventricle (group RV), a biventricle (group BV) and a left ven tricle (group LV). RESULTS Ten patients with atrioventricular valve regurgitation (AVVR) or hy poxia exhibited a low P(V) over dot O-2. After excluding these patients, al though P(V) over dot O-2 did not correlate with hemodynamics, except ventri cular ejection fraction (p < 0.02), it correlated with age at the Fontan op eration and exercise test (p < 0.002). The P(V) over dot O-2 was higher in group LV (63 +/- 9%) than in groups RV (55 +/- 9%) and BV (55 +/- 12%) (p < 0.01), while an inverse correlation between P(V) over dot O-2 and age at o peration was demonstrated only in group RV (p < 0.05). Groups RV or BV and age at exercise test were associated with a lower P(V) over dot O-2, wherea s group LV was an independent predictor of a higher P(V) over dot O-2 (p < 0.01). During 4.2 years of follow-up, a decrease in peak heart rate was rel ated to a decrease in P(V) over dot O-2 (p < 0.05). The P(V) over dot O-2 d ecreased in group RV (p < 0.01). CONCLUSIONS In addition to AVVR, hypoxia, and heart rate response, ventricu lar morphology is related to exercise capacity. Early Fontan operation may be beneficial in terms of exercise capacity, especially in the group RV pat ients. (J Am Coll Cardiol 2001;37:1967-74) (C) 2001 by the American College of Cardiology.