Surgical Strategy of Mitral Valve Repair in Transmitral Septal Myectomy for Hypertrophic Obstructive Cardiomyopathy

Reply to Surgical Strategy of Mitral Valve Repair in Transmitral Septal Myectomy for Hypertrophic Obstructive Cardiomyopathy

We read with great interest the recent article by El-Sayed Ahmad et al[1] who reported the excellent results of transmitral myectomy for symptomatic hypertrophic obstructive cardiomyopathy (HOCM). The transmitral approach not only provides a good view of the septum and its relationship with subvalvular apparatus but also reduces the manipulation difficulty in complex cases, such as mid-ventricular obstruction. However, this approach has a controversy about how to manage the mitral valve. In HOCM combined with intrinsic mitral valve diseases, the transmitral approach would be beneficial for concomitant mitral valve repair or replacement. In the above study, all mitral valvuloplasty patients received patch extension with the anterior mitral leaflet (AML). The length of the AML and correspondingly the size of the AML after patch extension were not detailed in the article. In our opinion, we do not recommend patch extension for all HOCM patients, especially those who have elongated AML. A patch was aimed to move the coaptation point horizontally away from the septum, preventing systolic anterior motion (SAM). However, we observed that a prolonged AML or an oversized patch resulting in residual length of the AML beyond the coaptation point could create SAM on the contrary ([Fig. 1]). The severity of SAM increases with the length of the redundant leaflet. In such situation, directly reattached AML or Alfieri Stich is the alternative strategy.

Fig. 1 The postoperatively systolic anterior motion was observed due to residual length of anterior mitral leaflet (white arrow).

Besides, the authors elaborated that annuloplasty of mitral valve was performed in 11 patients, without any left ventricular outflow tract (LVOT) obstruction or more than moderate mitral regurgitation at last follow-up. In our experience, we supposed annuloplasty was necessary, because it has been one of the standard mitral valve repair procedures to restore annular shape. Furthermore, primitive transmitral septal myectomy, the Morrow procedure via robotic approach, also applied patch extension with annuloplasty. Then we found the efficacy of patch extension alone was satisfactory. We were more concerned the annuloplasty might restrict the motion of the posterior leaflet and displace residual leaflet into the ventricle, leaving a risk of dynamic LVOT obstruction postoperatively. Therefore, we performed annuloplasty unless mitral annular dilatation noted, which is rare in HOCM. Ahmed et al[2] reported that in HOCM with ruptured mitral chordae tendineae, mitral valve repair with or without posterior band annuloplasty showed no prominent difference in LVOT gradient. It leads to another key question: is there a difference between patch extension with and without annuloplasty in transmitral septal myectomy for HOCM?

Publication History

Received: 08 June 2022

Accepted: 18 July 2022

Article published online:
22 August 2022

• References

• 1 El-Sayed Ahmad A, Salamate S, Giammarino S, Ciobanu V, Bakhtiary F. Transmitral septal myectomy and mitral valve surgery via right mini-thoracotomy. J Thorac Cardiovasc Surg 2023; ;(this issue) DOI: 10.1055/s-0042-1744261.
• 2 Ahmed EA, Schaff HV, Geske JB. et al. Optimal management of mitral regurgitation due to ruptured mitral chordae tendineae in patients with hypertrophic cardiomyopathy. J Semin Thorac Cardiovasc Surg 2022; ;S1043-0679(22)00126-5 DOI: 10.1053/j.semtcvs.2022.05.008.