Hypertrophic Obstructive Cardiomyopathy and Subvalvular Mitral Apparatus Remodeling

Abstract

We read with great interest the contribution of Wei and colleagues [1Wei L.M. Thibault D.P. Rankin J.S. et al.Contemporary surgical management of hypertrophic cardiomyopathy in the United States.Ann Thorac Surg. 2019; 107: 460-466Abstract Full Text Full Text PDF PubMed Scopus (32) Google Scholar] on the role of mitral valve in the systolic anterior motion (SAM)-related left ventricle outflow (LVOT) obstruction in patients with hypertrophic obstructive cardiomyopathy (HOCM). About one third of septal myectomy (SM) required mitral valve operation. Surprisingly, the most represented procedure in the repair group was annuloplasty, a well-known risk factor for SAM. Several malformations can affect the mitral valve in patients with HOCM [2Silbiger J.J. Abnormalities of the mitral apparatus in hypertrophic cardiomyopathy: echocardiographic, pathophysiologic, and surgical insights.J Am Soc Echocardiogr. 2016; 29: 622-639Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar] and it is almost a constant to observe abnormal chordae and papillary muscles (PM) that deserve some consideration during HOCM surgery. We introduced the concept of “subvalvular mitral apparatus remodeling” [3Raffa G.M. Romano G. Turrisi M. et al.Pathoanatomic findings and treatment during hypertrophic obstructive cardiomyopathy surgery: the role of mitral valve.Heart Lung Circ. 2019; 28: 477-485Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar] aimed at freeing the posterior motion of the anterior mitral leaflet away from the septum, moving back the coaptation plane of the mitral valve, in order to abolish the SAM and LVOT obstruction. We reviewed the charts of 43 consecutive patients (age, 56 ± 11 years; 25 women) who undewent HOCM surgery since 2007. “Subvalvular mitral apparatus remodeling” included secondary chordae (90%), PM, and muscularis trabeculae resection (78%), and PM splitting and elongation (42%) that were variably added to septal myectomy (100%). Six procedures (14%) involved the posterior mitral leaflets, through a transatrial approach. In 1 case the mitral valve had to be replaced. There was no hospital mortality. At follow-up (4 ± 3 years) the NYHA class (from 2.8 ± 0.6 to 1.3 ± 0.6, p < 0.0001), LVOT gradient (from 98 ± 37 to 17 ± 14 mm p < Hg, p < 0.0001), mitral regurgitation (from grade 3 ± 1 to 1 ± 0.5, p < 0.0001), and septum thickness (from 19 ± 3 to 14 ± 2 mm, p < 0.0001) were reduced. Minimal late death (1 patient) and reoperation for recurrent LVOT gradient (1 patient) occurred. Moreover, the subvalvular apparatus plays a major role in the etiology of LVOT obstruction in patients with a minor degree of septal hypertrophy (≤15 mm) [2Silbiger J.J. Abnormalities of the mitral apparatus in hypertrophic cardiomyopathy: echocardiographic, pathophysiologic, and surgical insights.J Am Soc Echocardiogr. 2016; 29: 622-639Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar]. The surgical treatment of pathologic chordae and PM has acquired a major role during HOCM surgery [2Silbiger J.J. Abnormalities of the mitral apparatus in hypertrophic cardiomyopathy: echocardiographic, pathophysiologic, and surgical insights.J Am Soc Echocardiogr. 2016; 29: 622-639Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar]: It should be included in the definition of extended SM as a single procedure, having a different target from the mitral valve operation reported in the Adult Cardiac Surgery Database registry. Notably, we argue that how many of these techniques, nowadays worldwide adopted, are classified by The Society of Thoracic Surgeons participating centers as “SM alone” result in a misinterpretation of the results and underline the need for further classification in the STS registry. Contemporary Surgical Management of Hypertrophic Cardiomyopathy in the United StatesThe Annals of Thoracic SurgeryVol. 107Issue 2PreviewThe primary surgical therapy for hypertrophic cardiomyopathy with obstruction is septal myectomy (SM). The current outcomes of SM with and without concomitant mitral operations in the United States was examined using The Society of Thoracic Surgeons database. Full-Text PDF