The atrial electrocardiogram as a guide to prognosis after mitral valvotomy.

A study has been made of serial electrocardiograms of patients with mitral stenosis in sinus rhythm, whose clinical progress was followed for at least four years after mitral valvotomy. The behaviour of the left atrial P wave after operation has been examined with special reference to its relationship to continued clinical progress. In addition, the form of the P wave in the pre-operative electrocardiogram has been studied in relation to the degree of stenosis as found at operation and also to the severity of pulmonary hypertension. Some of our first patients with mitral stenosis treated by mitral valvotomy, remaining in sinus rhythm post-operatively and followed now for four to eight years afterwards, have required a second valvotomy. At the second operation the valve orifice was found to have again diminished in size and in some it was as small as before. Although these patients appeared to have gained great benefit from the first operation during the first two years, and although the surgeon judged the degree of splitting in most to have been satisfactory, the left atrial electrocardiogram did not improve to the same degree as in other successful patients until after the second more radical operation. Absence of significant improvement in the left atrial electrocardiogram after the first operation suggested inadequate relief of stenosis. In this way the post-operative left atrial P wave has acted as a guide to prognosis in this group of patients in sinus rhythm, and has predicted those likely to require a second mitral valvotomy at a later date.