The medical records and results of cardiac magnetic resonance imaging and cardiopulmonary exercise testing of 25 consecutive eligible patients were reviewed. Twenty age- and gender-matched normal subjects were enrolled as cardiac magnetic resonance control. End-diastolic, end-systolic and stroke volumes, and ejection fraction (EF) were determined for the total RV and its components.
Of the 25 patients, 44% maintained normal exercise capacity. RV outlet EF was higher ( P = 0.02) and RV incisions smaller ( P = 0.04) in patients with normal exercise capacity than those with subnormal exercise capacity. Predicted peak oxygen consumption correlated better with the RV outflow tract EF than with the EF of other components of the RV or the global EF ( r = 0.59; P = 0.002). Multivariate analysis showed the RV outflow tract EF to be the only independent predictor of exercise capacity (ß = 0.442; P = 0.02).
Exercise capacity is preserved in some tetralogy of Fallot patients with severe RV dilatation. RV outflow tract EF is independently associated with exercise capacity in such patients, and could be a reliable determinant of intrinsic RV performance.