The middiastolic flow of mitral L wave may result from pathologies that impair the diastolic function of the heart. Echocardiographic examination of a 48-year-old female patient with a three-year history of partial pericardiectomy showed mild left ventricular hypertrophy, mild mitral regurgitation, and mitral annular calcification. During pulse-Doppler examination, a prominent forward transmitral flow (mitral L wave) was noted. The patient developed supraventricular tachycardia attacks on simultaneous electrocardiographic monitoring, during which the mitral L wave disappeared, but E and A waves sustained. Variations in the velocities of the forward transmitral flow were less than 25% during deep inspiration. Tissue Doppler imaging showed equal velocities (0.06 m/sec) of the E' and A' waves recorded at the lateral mitral annulus.