ROLE OF PAPILLARY-MUSCLE DYSFUNCTION IN THE PATHOGENESIS OF MITRAL REGURGITATION IN MYOCARDIAL-INFARCTION - A STUDY USING COLOR DOPPLER-ECHOCARDIOGRAPHY

To elucidate the pathogenesis of mitral regurgitation (MR) after myoca rdial infarction (MI), the incidence of papillary muscle dysfunction ( PMD), mitral annular size, and the extent of wall-motion abnormalities were examined in 81 patients with previous MI by two-dimensional echo cardiography and real-time two-dimensional Doppler flow imaging. The p revalence of pathological MR was lower in patients with anterior MI (3 6%) than in those with inferior (65%) or anterior and inferior MI (88% ) (P < 0.01 vs anterior MI group). The incidence of PMD in patients wi th MR in the anterior MI group (15%) was lower than that in the inferi or (50%, P < 0.01) or anterior and inferior MI group (43%, P < 0.05). The mitral annular dimension in patients with MR was significantly gre ater than in those without MR, but it was similar among the three grou ps. The extent of wall-motion abnormality correlated significantly wit h the area of MR jet in the anterior MI group (y = 3.1x + 15.5, r = 0. 52, P < 0.01) and in the inferior MI group (y = 8.3x + 32.7, r = 0.57, P < 0.01). However, the slope of this relationship was significantly steeper in the inferior MI group than in the anterior MI group (P < 0. 05). These results indicated that the degree of MR with inferior MI wa s greater than with anterior MI for a given MI area. PMD may play an i mportant role in the higher prevalence and greater degree of MR in inf erior MI.