Noninvasive assessment of myocardial contractility in asymptomatic patients with sever aortic regurgitation and normal left ventricular ejection fraction at rest.

In 14 asymptomatic patients with isolated aortic insufficiency the slope k of the end-systolic pressure-volume relation was determined noninvasively with equilibrium radionuclide angiography. The results were compared with changes in left ventricular ejection fraction during maximal physical stress. Nine normal volunteers served as a control group. Patients with aortic insufficiency did not differ significantly from the control group with respect to left ventricular ejection fraction at rest (aortic insufficiency 62 + 8 percent, control 65 +/- 6; probability [p] = not significant [NS]), physical work capacity (aortic insufficiency 113 +/- 32 watts, control 117 +/- 25; p = NS) or age (aortic insufficiency 40 +/- 10 years, control 47 +/- 7; p = NS). The slope (k) of the end-systolic pressure-volume relation was found to be significantly lower in the group with aortic insufficiency (3.1 +/- 1.1) than in the control group (4.1 +/- 0.5; p less than 0.05). Patients with aortic insufficiency could be classified into two subgroups with respect to the slope k. In subgroup A (n = 7) the slope fell within the normal range (4.0 +/- 0.6) as defined by the control group, and the left ventricular exercise reserve was normal (6 percent +/- 1). In subgroup B (n = 7) the slope was significantly lower (2.2 +/- 0.6, p less than 0.01), indicating depressed myocardial contractility, and all patients experienced left ventricular dysfunction during exercise (left ventricular exercise reserve -5 +/- 5 percent). Thus, noninvasive determination of the end-systolic pressure-volume relation identified two subsets of asymptomatic patients with aortic insufficiency, one with impaired myocardial contractility and normal left ventricular exercise reserve and a second group with depressed myocardial contractility and left ventricular dysfunction during exercise. Therefore, an abnormal baseline contractile state in asymptomatic patients with aortic insufficiency may be uncovered by noninvasive determination of the end-systolic pressure-volume relation or by assessing the left ventricular exercise reserve. Serial studies in a larger group of patients undergoing surgical correction of the valve lesion are indicated to determine whether this information will be helpful in evaluating when to operate on asymptomatic patients with aortic insufficiency.