[Effect of valve replacement on left ventricular function in chronic aortic regurgitation].

To ascertain the optimal time for surgery in chronic aortic regurgitation (AR), 66 patients with and without surgical correction were reviewed from the standpoint of left ventricular (LV) function based on their serial echocardiographic studies. Aggravation of the clinical status was usually associated with enlarged LV dimension, decreased %fractional shortening (%FS), and increased LV end-systolic meridional stress (sigma m). Fourteen patients developed congestive heart failure during follow-up periods of up to five years, and most of their echocardiographic findings showed %FS less than 27%, and LV end-systolic dimension (LVD) greater than 50 mm. Thirty-two patients underwent surgery. Preoperatively, sigma m and %FS were closely correlated, including cases whose %FS was decreased. This linear regression equation became steeper with dobutamine administration; however, in patients, whose mean preoperative LVD value exceeded 50 mm, the %FS remained depressed (delta FS less than 6%) and sigma m did not significantly decrease during dobutamine administration. Marked or moderate resolution of LV dilatation and hypertrophy was observed in all patients postoperatively. Compared to patients with preoperative %FS greater than or equal to 27%, much more time was required for recovery of patients with %FS less than 27%, though their %FS and their exercise capacity improved within two years of surgery. Immediate postoperative recovery was observed in cases with excellent preoperative response to dobutamine (delta FS greater than or equal to 6%). However, in patients with severely depressed preoperative %FS less than 20%, postoperative improvement was not so marked and the surgical results were unsatisfactory. From these results, we concluded that the optimal time for surgery for AR is when %FS = 27% and LVDs = 50 mm.