Mitral Regurgitation in Hypertrophic Obstructive Cardiomyopathy Patients
Among patients with hypertrophic obstructive cardiomyopathy (HOCM) undergoing extended transaortic septal myectomy, what are the incidence and outcomes of concomitant mitral valve (MV) surgery?
Clinical data from 2,107 septal myectomy operations performed in adults from January 1993 to May 2014 at Mayo Clinic (Rochester, MN) were retrospectively reviewed. Patients with prior MV operation and apical hypertrophic cardiomyopathy were excluded. Overall, 2,004 operations were performed in 1,993 patients.
Preoperative MR was grade ≥3 (of 4) in 1,152 operations (57.5%). Systolic anterior motion (SAM) of mitral leaflets caused the MR in most patients. However, intrinsic MV disease was identified preoperatively in 99 patients, all of whom had MV surgery (with septal myectomy). In 1,905 operations, no intrinsic MV disease was identified preoperatively; in 1,830 (96.1%), septal myectomy was performed without a direct MV procedure. For 75 patients, intrinsic MV disease discovered intraoperatively led to concomitant MV repair (86.7%) or replacement (13.3%). After isolated septal myectomy, the percentage of patients with MR grade ≥3 decreased from 54.3% to 1.7% (p = 0.001) on early postoperative echocardiography. Among 174 patients with concomitant MV surgery, late survival was superior with MV repair (n = 133 [76.4%]) versus replacement (10-year survival 80.0% vs. 55.2%, p = 0.002).
In most patients with HOCM, MR related to SAM of the MV is relieved through adequate myectomy. Concomitant MV surgery is rarely necessary unless intrinsic MV disease is present. The authors concluded that, when MV procedures are required, repair is preferred because of improved survival compared with replacement.
Abnormal MV anatomy can occur, and can contribute to outflow obstruction and/or MR among patients with HOCM. This large single-center study found that myectomy alone adequately relieved MR caused by mitral leaflet SAM, at least during early follow-up. When surgical mitral intervention was performed, repair was associated with superior late survival compared to MV replacement; however, as patients subjected to repair and replacement might have been different, it might be difficult to conclude that it is the repair that is responsible for superior outcomes.
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