Systolic anterior motion of the mitral chordae tendineae: prevalence and clinical and Doppler-echocardiographic features.

The objective of this investigation was to determine the prevalence and clinical associations of systolic anterior motion (SAM) of the mitral chordae (chordal SAM) in patients without evidence of hypertrophic cardiomyopathy. Although SAM of the mitral valve is thought to be a specific marker of hypertrophic obstructive cardiomyopathy, little is known about the clinical significance of chordal SAM either as an isolated echocardiographic finding (ICSAM) or in patients with mitral valve prolapse (MVP). A retrospective search of the clinical echocardiographic database was made to identify studies demonstrating chordal SAM with no other echocardiographic features of hypertrophic cardiomyopathy. The prevalence of chordal SAM was also ascertained in a group of 97 normal control subjects. Clinical, demographic, and two-dimensional and Doppler echocardiographic characteristics were compared between patients with and without MVP. Chordal SAM was identified in 3.9 percent of clinical studies but was rarely seen in normal volunteers (1 percent). Of the 57 patients with chordal SAM, 21 had systemic or cardiovascular conditions other than MVP associated with SAM (including 7 with aortic insufficiency and 8 with secondary concentric left ventricular hypertrophy), 18 (32 percent) had MVP, and 19 (33 percent) had no associated cardiovascular or systemic condition. These 19 patients with ICSAM were similar to patients with MVP and SAM with respect to age (44 +/- 8 vs 41 +/- 17 years), blood pressure, left ventricular wall thickness, ejection fraction, left atrial size, degree of mitral insufficiency, and left ventricular outflow tract velocity. Indications for the echocardiographic studies were similar between the two groups (chest pain, syncope, arrhythmia, cardiac source of embolus, and suspected MVP), but more patients in the ICSAM group were men (16 of 19 vs 8 of 18; p < 0.05). In conclusion, patients with ICSAM and CSAM associated with MVP are virtually indistinguishable by clinical, demographic, or Doppler-echocardiographic features. The syndrome of ICSAM deserves further study as a potentially clinically significant echocardiographic variant of the floppy mitral valve/MVP syndrome.