Is Septal Myectomy Needed During Mitral Replacement for Hypertrophic Obstructive Cardiomyopathy?

Abstract

We read the article by Wehman and colleagues [1Wehman B. Ghoreishi M. Foster N. et al.Transmitral septal myectomy for hypertrophic obstructive cardiomyopathy.Ann Thorac Surg. 2018; 105: 1102-1108Abstract Full Text Full Text PDF PubMed Scopus (18) Google Scholar] describing their technique for transmitral septal myectomy with an experience in 20 consecutive patients. We agree with the authors’ assertion that patients with hypertrophic obstructive cardiomyopathy (HOCM) not infrequently have structural abnormalities of the mitral valve leaflets, chord, and papillary muscle insertion [2Kaple R.K. Murphy R.T. DiPaola L.M. et al.Mitral valve abnormalities in hypertrophic cardiomyopathy: echocardiographic features and surgical outcomes.Ann Thorac Surg. 2008; 85: 1527-1535Abstract Full Text Full Text PDF PubMed Scopus (123) Google Scholar]. Mitral valve replacement (MVR) was performed in almost half of the patients (45%, n = 9 of 20), and most prostheses were mechanical (66%, n = 6 of 9). Importantly, the authors identified the need to replace the mitral valve, without repair attempt, on the basis of an initial evaluation of morphology in more than half of the patients (56%, n = 5 of 9). We reviewed our own institutional results of 42 consecutive patients with HOCM requiring MVR. Similar to the findings of Wehman and colleagues [1Wehman B. Ghoreishi M. Foster N. et al.Transmitral septal myectomy for hypertrophic obstructive cardiomyopathy.Ann Thorac Surg. 2018; 105: 1102-1108Abstract Full Text Full Text PDF PubMed Scopus (18) Google Scholar], the indication for MVR was mitral valve disease not amenable to repair. Right-sided thoracotomy was performed in 69% of cases, particularly if MVR was planned (43%, n = 18 of 42). Most patients (74%, n = 31 of 42) underwent MVR without septal myectomy. Mechanical prostheses were used in all cases. In our series, MVR alone versus MVR with septal myectomy resulted in no significant differences in postoperative left ventricular outflow tract gradient (6 ± 8 mm Hg vs 6 ± 8 mm Hg, p = 0.8), symptoms at follow-up (median New York Heart Association functional class I vs class I, p = 0.4), or 5-year survival (87 ± 59% vs 75 ± 22%, p = 0.13). We therefore conclude that addition of septal myectomy to mechanical MVR may not be needed, if MVR is planned preoperatively. Septal myectomy remains the procedure of choice for patients with symptomatic HOCM, and combined septal myectomy with mitral repair also remains the procedure of choice for patients with HOCM and substantial mitral valve disease. However, for patients with HOCM and significant mitral valve disease that is not amenable to repair, MVR alone with a mechanical prosthesis can provide predictable relief of obstruction and mitral regurgitation [3Cooley D.A. Leachman R.D. Hallman G.L. Gerami S. Hall R.J. Idiopathic hypertrophic subaortic stenosis. Surgical treatment including mitral valve replacement.Arch Surg. 1971; 103: 606-609Crossref PubMed Scopus (54) Google Scholar]. Transmitral Septal Myectomy for Hypertrophic Obstructive CardiomyopathyThe Annals of Thoracic SurgeryVol. 105Issue 4PreviewIntrinsic abnormalities of the mitral valve are common in patients with hypertrophic cardiomyopathy and may need to be addressed at operation. Full-Text PDF