Accuracy of Jet Direction on Doppler Echocardiography in Identifying the Etiology of Mitral Regurgitation in Obstructive Hypertrophic Cardiomyopathy

Background: Mitral valve regurgitation (MR) mediated by systolic anterior motion (SAM) in obstructive hypertrophic cardiomyopathy (HCM) is traditionally characterized by a posteriorly directed jet on Doppler echocardiography. Many believe that MR in the absence of a posteriorly directed jet signals the presence of intrinsic mitral valve (MV) disease. Methods: A total of 709 adult patients with obstructive HCM who underwent septal myectomy were evaluated; 330 of these patients had >2 + MR preoperatively and constituted the study group. SAM-mediated MR was defined as MR that was eliminated or substantially reduced by myectomy for relief of left ventricular outflow tract obstruction with no need for MV intervention. Results: On preoperative transthoracic echocardiography, 168 of 258 patients with SAM-mediated MR and nine of 28 patients with intrinsic MV disease had isolated posterior jets, corresponding to sensitivity and specificity of 65.1% and 67.9% for identifying SAM-mediated MR; the positive predictive value was 94.9% and the negative predictive value was 17.4%. On prebypass transesophageal echocardiography, 169 of 284 patients with SAM-mediated MR and five of 28 patients with intrinsic MV disease had isolated posterior jets, corresponding to sensitivity and specificity of 59.5% and 82.1%; the positive predictive value and negative predictive value were 97.1% and 16.7%. Conclusion: A posteriorly directed jet of MR in obstructive HCM correlates highly with SAM as the underlying pathophysiologic mechanism, but because of the low negative predictive value, clinicians should be cautious in using the jet direction of MR on preoperative transthoracic echocardiography to guide the decision for concomitant MV surgery during septal myectomy for HCM.