EFFECTS OF LONG-TERM ENALAPRIL THERAPY ON LEFT-VENTRICULAR DIASTOLIC PROPERTIES IN PATIENTS WITH DEPRESSED EJECTION FRACTION

Background. The aim of the present study was to analyze the changes in left ventricular diastolic function that occur in patients with chronic severe left ventricular systolic dysfunction in the absence or presence of prolonged therapy with an angiotensin converting enzyme inhibitor. Methods and Results. Left ventricular function data (cineangiography plus Millar, frame-by-frame analysis) and right ventricular volumes (radionuclide angiography) were obtained at baseline and after an average follow-up of 12.4 months in 42 patients with a left ventricular ejection fraction of 35% or less. After baseline measurements, the patients were randomized to placebo (n=16) or enalapril (10 mg BID, n=26). In the placebo group, the changes in left ventricular function were characterized by increases in end-diastolic (159+/-43 to 170+/-44 ML/M2 ) and end-systolic (119+/-38 to 128+/-49 mL/M2) volumes accompanied by a downward and rightward shift of the diastolic pressure-volume relation. In contrast, decreases in end-diastolic (166+/-43 to 156+/-47 mL/M2 ) and end-systolic (125+/-43 to 111+/-42 mL/m2) volumes accompanied by a slight upward and leftward shift of the diastolic pressure-volume relation were noted in the enalapril group. These changes in left ventricular volumes were significantly different between groups (both P<.005) but were not attended by changes in left ventricular end-diastolic pressure, in time constant of isovolumic pressure decrease, or in right ventricular volumes. However, the chamber stiffness constant 8 decreased from 0.044+/-0.027 to 0.032+/-0.019 mL-1/m2 in the placebo group, whereas it increased insignificantly in the enalapril group (0.040+/-0.028 to 0.041+/-0.028 mL-1/m2). These changes in chamber stiffness constant beta between baseline and follow-up were significantly different between placebo and enalapril groups (P<.05). Another index of chamber compliance, DELTA V/DELTA P, also confirmed the presence of opposite changes in left ventricular chamber compliance in the placebo group and in the enalapril group. The mean diastolic wall stress increased with placebo but not with enalapril (+51 versus - 13 kdyn/cm2; P<.04) whereas left ventricular mass and the indexes of left ventricular sphericity tended to improve in the enalapril group. The changes in plasma levels of norepinephrine, atrial natriuretic peptide, and arginine vasopressin were, however, comparable in both groups. Conclusions. The data indicate that in patients with severe systolic left ventricular dysfunction, the progressive left ventricular dilatation was accompanied by a decrease in left ventricular chamber stiffness; enalapril therapy was able to prevent or partially reverse these changes and tended to reduce left ventricular mass and ventricular sphericity. Those changes were suggestive of partial reversal of left ventricular remodeling by enalapril administration.