Statistical comparison of M mode and two dimensional echocardiographic diagnosis of flail mitral leaflets.

Forty-five patients who had surgical therapy for pure mitral insufficiency were evaluated prospectively with both M mode and two dimensional echocardiography; 26 patients (Group I) had a flail mitral valve leaflet, and 19 patients (Group II) had intact chordae tendineae. The M mode echocardiographic criteria of a flail valve (systolic left atrial echoes, systolic mitral valve flutter, diastolic mitral flutter and chaotic paradoxic diastolic posterior leaflet motion) were compared statistically with the two dimensional echocardiographic criterion (loss of systolic leaflet coaptation). The presence of one M mode echocardiographic finding had a sensitivity of 60 percent, a specificity of 53 percent, a predictive accuracy of 63 percent and a predictive value of 50 percent. The sensitivity (96 percent), specificity (84 percent), predictive accuracy (89 percent) and predictive value (94 percent) of the two dimensional echocardiogram were statistically superior to those of the M mode study (p less than 0.05 or better for each criterion). Thus, two dimensional echocardiography is distinctly superior to M mode echocardiography in the diagnosis of flail mitral valve leaflets.