Eighteen patients with isolated stenosis of left anterior descending artery, were randomly given 0.2 mg of nifedipine (Group II) or its solvent (Group I) via balloon catheter positioned across the lesion immediately prior balloon occlusion. Peak velocity of early (E peak) and late (A peak) filling, velocity flow integral at early (E area) and late (A area) filling and their ratios (by echo-Doppler) and heart rate, mean aortic and wedge (W) pressures were measured at baseline, 15 and 30 s during balloon occlusion and 10 min after balloon deflation. In Group I we observed a significant decrease in either E peak at 15 and 30 s (-24.7%, -29.3% respectively) and E area (-32.8%, -40.0% respectively) with a non significant increase in both A peak and A area. Accordingly, either E/A peak ratio and E/A area ratio decreased significantly. In Group II no significant changes were observed in the echo-Doppler parameters of left ventricular filling. Wedge pressure also significantly increased in Group I at 15 and 30 s (68.7% and 97.9% respectively), while a significant increase in Group II occurred only at 30 s (32.5%). Heart rate significantly increased only in Group I at 15 and 30 s (10.3% and 11% respectively), while aortic pressure remained unchanged in both groups. Thus, nifedipine given intracoronary in the post-stenotic area just before balloon occlusion prevents left ventricular filling dynamic alteration by preserving early filling.