The effect of mitral commissurotomy on the natural history of rheumatic heart disease

Abstract

Dr. Nicholas P. Christy: This exercise points out some common misconceptions concerning the natural history of rheumatic heart disease, emphasizing the relative rarity of valvular disease following an attack of acute rheumatic fever, and showing that only a small proportion of patients who have valvular involvement are likely to become ideal candidates for mitral commissurotomy. An attempt was made to assess the effect of this operative procedure upon the natural history of rheumatic heart disease, an assessment difficult to make in the absence of a truly comparable untreated control group. Of 130 patients subjected to commissurotomy who were followed up for periods as long as eight years after surgery, careful direct clinical study showed improvement in 44 per cent, no change in 21 per cent; 11 per cent were worse and 24 per cent died. The changes in objective findings were less striking than the changes in symptoms. The incidence of hemoptysis was sharply reduced and congestive heart failure and dyspnea were improved in over half the patients; on the other hand, murmurs and cardiac size tended either to remain the same or to change in an adverse direction. Operative deaths were chiefly caused by emboli, congestive heart failure and bacterial endocarditis. The operative outcome seemed to be adversely affected by the preexistence of severe, long-standing heart failure, calcification of the mitral valve, and a cardiac classification of IV. All observers believed that present criteria for selection of patients for commissurotomy are far from perfect, but the participants agreed that youth, a small heart in regular sinus rhythm, and recent deterioration predisposed to a good operative result. Objective observations of the effect of the operation upon the natural history of rheumatic heart disease are recorded. Right heart catheterization showed early physiologic improvement following commissurotomy, and demonstrated that such improvement could be sustained for years. The value of left heart catheterization in selected patients (those with associated mitral insufficiency or aortic valvular disease, patients suspected of restenosis of the valve after commissurotomy) was indicated as a measure of the degree of mitral block. It was suggested that the spectrum of patients with rheumatic heart disease can be roughly arranged in groups in terms of myocardial versus mechanical (mitral block) lesions, a classification which may lend further aid in evaluating the suitability of patients for operation. The surgical problem was discussed in relation to the mechanical changes that may conduce to restenosis of the valve after operation, e.g., increasing stiffness of the valve itself, and shortening and fixation of the chordae tendineae. It is hoped that the insertion of prosthetic mitral valves may offer hope for the future. The somewhat pessimistic operative results here recorded are at variance with certain earlier, more enthusiastic reports. The discrepancies depend upon several factors: duration and objectivity of medical follow-up; additional changes in the natural history of rheumatic fever superimposed by other therapy, especially prophylaxis; and differences of opinion about what is the true natural history of this disorder. Certainly the natural history is changing, and mitral commissurotomy, in a very small group of the total number of rheumatic subjects, appears to be contributing to the change.