Earlier studies have suggested that mitral regurgitation (MR) augments early left ventricular (LV) diastolic filling. To determine whether MR affects early diastolic filling in patients with abnormal diastolic filling, transmitral pulsed-wave Doppler recordings were used to study 32 normal subjects, 21 patients with LV hypertrophy, 23 with LV hypertrophy and MR and 15 patients with MR. Patients with MR had increased peak early filling velocities (MR 108 +/- 27 cm/s, normal 80 +/- 16 cm/s, p less than 0.01), peak atrial filling velocities (MR 72 +/- 18 cm/s, normal 55 +/- 12 cm/s, p less than 0.05) and increased deceleration rates (MR 5.0 +/- 1.9 m/s2, normal 3.5 +/- 1.2 m/s2, p less than 0.05). Patients with LV hypertrophy had reduced peak early filling velocities (69 +/- 14 cm/s, p less than 0.05) and increased peak atrial filling velocities (83 +/- 16 cm/s, p less than 0.001). There was also an increase in the atrial filling fraction and reduction in the rapid filling fraction as compared with normal patients. Patients with LV hypertrophy and MR had increased peak early filling velocities (98 +/- 26 cm/s, p less than 0.01 vs normal, p less than 0.001 vs LV hypertrophy patients), increased atrial filling velocities (84 +/- 27 cm/s, p less than 0.001 vs normal), increased deceleration rates (4.4 +/- 2.4 m/s2, p less than 0.05 vs normal) and a normal distribution of diastolic filling. Within the LV hypertrophy and MR group, diastolic filling parameters were similar when patients were subgrouped on the basis of auscultability of MR. MR augments early diastolic filling and may tend to normalize diastolic filling patterns in LV hypertrophy patients.(ABSTRACT TRUNCATED AT 250 WORDS)