Objectives. We sought to assess whether in clinically stable patients with chronic heart failure (CHF) the prolongation (i.e., increase) of an initially short (less than or equal to 125 ms) Doppler transmitral deceleration time (DT) of early filling obtained with long-term optimal oral therapy predicts a more favorable prognosis. Background. It has been recently demonstrated that transmitral early DT is a powerful independent predictor of poor prognosis in patients with left ventricular dysfunction, However,)DT may change over time according to loading conditions and medical treatment. Method. One hundred forty four patients,vith CHF and a short DT (less than or equal to 125 ms) underwent repeat Doppler echocardiographic study 6 months after the initial examination, while clinically stable with optimal oral therapy, and mere then followed up for a mean period of 26 +/- 7 months. Results. After 6 months, DT had not changed in 80 patients (group 1), whereas it was significantly prolonged (> 125 ms) in the remaining 64 patients (group 2), Baseline Doppler echocardiographic features were similar in the two groups. No changes were found after 6 months in group 1, whereas group 2 showed a slight but significant (p < 0.01) reduction in end-systolic volume, an improvement in left ventricular ejection fraction (p < 0.01) and a decrease (p < 0.01) in the degree of tricuspid regurgitation, during follow-up, 37% of patients in group 1 experienced cardiac death versus 11% in group 2 (p < 0.0005). By Cox model analysis, prolongation of a short DT emerged as the single best predictor of survival (chi-square 15.70). Conclusions. The prolongation of an initially short DT obtained with long-term optimal oral therapy predicts a more favorable outcome in clinically stable patients with CHF. (C) 1998 by the American College of Cardiology.