To assess the accuracy of the exercise-induced decrease in the ratio of peak flow velocity in atrial systole to that in early diastole (A/E) for predicting an elevation of left ventricular filling pressure, supine bicycle ergometer exercise testing was performed in 27 consecutive patients with coronary artery disease. Doppler-derived transmitral flow velocities were recorded at rest and immediately after exercise. A/E decreased during exercise in 16 patients (group A) and increased in 11 (group B). Pulmonary artery wedge pressure (PAWP) increased notably from 7 mm Hg at rest to 26 mm Hg at peak exercise in group A (p less than 0.001). In contrast, PAWP increased slightly from 6 mm Hg to 10 mm Hg in group B (p less than 0.05). The cardiac index at peak exercise in group A was significantly lower than that in group B (p less than 0.05). These findings suggest that patients with an exercise-induced decrease in A/E might not increase their cardiac output. A significant negative correlation between PAWP and A/E was observed in patients with PAWP over 20 mm Hg (r = -0.74; p less than 0.005). The exercise-induced decrease in A/E showed a sensitivity of 100%, a specificity of 73%, and a predictive accuracy of 85% in detecting patients with PAWP over 20 mm Hg. These findings show that Doppler recordings of transmitral flow velocities during dynamic exercise can provide useful information concerning exercise-induced left ventricular dysfunction associated with markedly elevated filling pressures.