Relation between exercise-induced changes in ejection fraction and systolic loading conditions at rest in aortic regurgitation

To examine the role of systolic wall stress at rest in determining left ventricular performance during exercise in aortic regurgitation (AR), systolic wall stress (measured by M-mode echocardiography) was related to changes in left ventricular function during maximal exercise (evaluated by radionuclide ventriculography) in 30 patients with chronic aortic regurgitation. Of these 30 patients, 7 had a normal exercise response, defined as an absolute increase in ejection fraction of 5% or greater (Group I) and 23 had abnormal exercise response, defined as no change (< 5% change) or a decline (≤ 5%) in ejection fraction (Group II). Patients in Group I had a significantly lower radius/wall thickness ratio (2.5 ± 0.2 versus 3.1 ± 0.1, p < 0.01) and lower peak systolic wall stress (123 ¼ 11 versus 211 ¼ 12 × 10³ dynes/cm², p < 0.01) than patients in Group II. An increase in ejection fraction during exercise was seen in 6 of the 9 patients with normal systolic wall stress at rest (< 150 × 103 dynes/cm²), but in only 1 of 21 patients with elevated systolic wall stress (p < 0.001). Peak systolic wall stress at rest varied linearly and inversely with changes in left ventricular ejection fraction during exercise (r = 0.60, p < 0.001). Groups I and II did not differ in ejection fraction at rest, clinical symptoms or maximal work load achieved. These findings suggest that exercise-induced left ventricular dysfunction in patients with aortic regurgitation is the result of elevated left ventricular systolic wall stress; both echocardiographic evaluation of wall stress at rest and radionuclide determination of the exercise response identify a similar patient group that may be at a high risk of persistent symptoms and left ventricular dysfunction after aortic valve replacement.