Association between the exercise ejection fraction response and systolic wall stress in patients with chronic aortic insufficiency

Abstract

We studied the exercise ejection fraction response in 56 patients with chronic aortic insufficiency. All had left ventricular dilatation but preserved resting ejection fraction and minimal or no symptoms. The exercise ejection fraction increased by 0.05 units or greater in 18 (32%) patients (group I), remained within 0.05 units of the resting value in 18 (32%) patients (group II), and fell by 0.05 units or greater in 20 (36%) patients (group III). There were no significant differences among the groups in left ventricular end-diastolic dimension, end-systolic dimension, or fractional shortening by echocardiography or in resting left ventricular volumes and ejection fraction by radionuclide angiography. Left ventricular end-systolic wall stress was significantly higher in group III than in either group I or group II (89 ± 20 vs 70 ± 18 and 69 ± 17 x 103 dyne/cm2; p < .0001). Exercise capacity was significantly lower in group III than in groups I and II. These data demonstrate that patients with chronic aortic insufficiency whose ejection fraction falls during exercise have elevated resting left ventricular systolic wall stress, suggesting that left ventricular hypertrophy has not been adequate. Although these patients have a normal resting ejection fraction, left ventricular systolic pump performance cannot be sustained during exercise when wall stress rises further.