Aims
In patients with obstructive hypertrophic cardiomyopathy (HCM) and mild septal thickness undergoing myectomy, resecting fibrotic anterior mitral leaflet (AML) secondary chordae moves the mitral valve (MV) away from the outflow tract and ejection flow, reducing the need for a deep septal excision. Aim of the present study was to assess whether chordal resection has similarly favourable effects in patients with important hypertrophy, who represent the majority of patients with obstructive HCM.
Methods and results
The MV position in the ventricular cavity, assessed from echocardiography as AML-annulus ratio, was compared before and after chordal resection in 150 consecutive HCM patients with important (≥20 mm) and 62 with mild (≤19 mm) septal thickness undergoing myectomy. Preoperatively, MV position was displaced towards the septum to a similar extent in both groups. Postoperatively, AML-annulus ratio increased of an equal degree in both groups, from 0.43 ± 0.05 to 0.55 ± 0.06 (P < 0.001) a 28% increase, and from 0.43 ± 0.06 to 0.55 ± 0.06 (P < 0.001) a 26% increase, respectively, indicating a similar MV shift away from the outflow tract. When AML-annulus ratio was compared in the study cohort and 124 normal subjects, MV position was within normal range in <4% of patients preoperatively and normalized in >50% postoperatively.
Conclusions
In obstructive HCM, displacement of the MV apparatus into the outflow tract interferes with the ejection flow. Resection of fibrotic secondary chordae moves the MV apparatus away from the outflow tract and enlarges the outflow area independently of septal thickness, facilitating septal myectomy by reducing the need for a deep muscular excision.
Background and Aim:
Abnormalities of mitral valve (MV) apparatus are known to contribute to left ventricular (LV) outflow obstruction in hypertrophic cardiomyopathy (HCM). Purpose of this study is to report our experience with MV repair in patients with obstructive HCM undergoing surgical septal myectomy.
Methods:
From July 2013 to March 2018, 316 consecutive patients with obstructive HCM underwent surgical septal myectomy. Of these patients, 298 (94.3%) had associated MV repair and only 18 (5.7%) had MV replacement due to severe leaflets calcification and intrinsic MV disease. Age ranged from 15 to 85 years, mean 54 ± 15. Each patient had an outflow gradient ≥50 mmHg at rest or with physiologic provocation and disabling symptoms unresponsive to medical therapy.
Results:
Transaortic papillary muscle mobilization and cutting of fibrotic and retracted secondary MV chordae was performed, in association with septal myectomy, in all study patients. Plication of a redundant anterior MV leaflet was performed in 119 (37%) patients, and of the posterior leaflet in 29 (9%). Two patients died during hospitalization (0.6%), 8 patients (2.8%) had a residual postoperative resting gradient ≥30 mmHg, 6 (1.9%) patients had persistent important functional limitation (NYHA III), and 9 (2.8%) residual moderate-to-severe MV regurgitation, at the first postoperative evaluation.
Conclusions:
In our large HCM study cohort, transaortic extensive and systematic repair of the MV apparatus, combined with septal myectomy, was associated with a particularly low perioperative mortality, and abolition of resting LV outflow obstruction, MV regurgitation and heart failure symptoms in the great majority of patients.
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