Relation of left atrial size to pulmonary capillary wedge pressure in severe mitral regurgitation

4,071 consecutive cardiac catheterizations were reviewed retrospectively to obtain 56 cases of pure mitral regurgitation among whom chest X-ray, electrocardiography and echocardiography had been performed within 10 days of catheterization. Mitral regurgitation was mild to moderate (1-2+) in 7 of the 56 cases while 49 had more severe regurgitation (3-4+). Left atrial size as measured by echocardiography was found to be enlarged in all but 2 cases. A positive correlation between left atrial size and severity of mitral regurgitation, irrespective of the height of the pulmonary capillary wedge pressure V wave was demonstrated. There was no demonstrable, predictive relationship between left atrial size and pulmonary capillary wedge pressure or electrocardiographic or chest X-ray findings. We conclude that knowledge of left atrial size is predictive of the severity of mitral regurgitation; however, it is not possible to predict the pulmonary capillary wedge pressure or height of the V waves based on a knowledge of left atrial dilatation in patients with pure mitral regurgitation.