Minimally invasive septal myectomy for the treatment of hypertrophic obstructive cardiomyopathy and intrinsic mitral valve disease

A Narrative Review of Emerging Therapies for Hypertrophic Obstructive Cardiomyopathy

Hypertrophic obstructive cardiomyopathy is a hereditary condition that affects myocardial contraction. In case of failure of pharmacological treatment, alternative approaches might be used that include surgical myectomy, percutaneous transluminal septal myocardial ablation, and radiofrequency ablation. In respect of long-term advantages, surgical septal myectomy remains the therapy of choice for symptomatic hypertrophic obstructive cardiomyopathy. Alcohol septal ablation has been considered an alternative to surgical myectomy, which confers the benefits of a shorter hospital stay, less discomfort, and fewer complications. However, only expert operators should perform it on carefully chosen patients. Further, radiofrequency septal ablation reduces the left ventricular outflow tract gradient and improves the NYHA functional class of patients with hypertrophic obstructive cardiomyopathy, despite complications like cardiac tamponade and atrioventricular block. Further research with a larger sample size is required to compare the radiofrequency approach with established invasive treatment methods for hypertrophic obstructive cardiomyopathy. Septal myectomy has low morbidity and mortality rates, making it the preferred procedure; however, the efficacy and morbidity remain debatable. Advances in invasive techniques, including percutaneous septal radiofrequency ablation and transcatheter myotomy, have provided alternative approaches for reducing left ventricular outflow tract (LVOT) obstruction in patients who are not candidates for traditional surgical septal myectomy. Candidates for alcohol and radiofrequency septal ablation include patients with symptomatic hypertrophic obstructive cardiomyopathy, older adults, and those with multiple comorbidities.

Review of Contemporary Invasive Treatment Approaches and Critical Appraisal of Guidelines on Hypertrophic Obstructive Cardiomyopathy: State-of-the-Art Review

BACKGROUND

Hypertrophic obstructive cardiomyopathy (HOCM) is a heterogeneous disease with different clinical presentations, albeit producing similar dismal long-term outcomes if left untreated. Several approaches are available for the treatment of HOCM; e.g., alcohol septal ablation (ASA) and surgical myectomy (SM). The objectives of the current review were to (1) discuss the place of the standard invasive treatment modalities (ASA and SM) for HOCM; (2) summarize and compare novel techniques for the management of HOCM; (3) analyze current guidelines addressing HOCM management; and (4) offer suggestions for the treatment of complex HOCM presentations.

METHODS

We searched the literature and attempted to gather the most relevant and impactful available evidence on ASA, SM, and other invasive means of treatment of HOCM. The literature search yielded thousands of results, and 103 significant publications were ultimately included.

RESULTS

We critically analyzed available guidelines and provided context in the setting of patient selection for standard and novel treatment modalities. This review offers the most comprehensive analysis to-date of available invasive treatments for HOCM. These include the standard treatments, SM and ASA, as well as novel treatments such as dual-chamber pacing and radiofrequency catheter ablation. We also account for complex pathoanatomic presentations and current guidelines to offer suggestions for tailored care of patients with HOCM. Finally, we consider promising future therapies for HOCM.

CONCLUSIONS

HOCM is a heterogeneous disease associated with poor outcomes if left untreated. Several strategies for treatment of HOCM are available but patient selection for the procedure is crucial.

Transmitral Septal Myectomy and Mitral Valve Surgery via Right Mini-Thoracotomy

Background Transmitral myectomy for symptomatic hypertrophic obstructive cardiomyopathy is possible with existence of substantial mitral valve disease. We present herein our experience of minimally invasive transmitral septal myectomy combined with mitral valve surgery through right anterior mini-thoracotomy in the past 4 years at our institution.

Methods Between March 2017 and October 2020, 14 patients with hypertrophic obstructive cardiomyopathy and mitral valve disease required minimally invasive transmitral septal myectomy combined with mitral valve reconstruction or replacement at our institution. Mean age of patients was 54.2 ± 11.4 and 42.9% (n = 6) were female. Twelve patients (85.1%) were in New York Heart Association class III to IV and 6 patients (42.9%) presented with persistent atrial fibrillation. Clinical data were prospectively entered into our institutional database.

Results Cardiopulmonary bypass time accounted for 140.2 ± 32.6 minutes and the myocardial ischemic time was 78.5 ± 12.4 minutes. Thirty-day mortality and overall mortality were zero. Peak ventricular outflow gradient decreased from 75.2 ± 12.7 to 9.4 ± 2.3 mm Hg (p < 0.0001). Simultaneously, mitral valve reconstruction and replacement were performed in 11 (78.6%) and 3 (21.4%) patients, respectively. No systolic anterior motion was seen in patients with mitral valve repair. No conversion to full sternotomy and/or rethoracotomy was noted. During a mean follow-up period of 24 ± 13 months, no patient required reoperation, no recurrence mitral regurgitation, and left ventricular outflow tract obstruction.

Conclusion Transmitral septal myectomy combined with mitral valve surgery through right anterior mini-thoracotomy can be performed safely with excellent surgical outcomes.

Thoracoscopic Trans-mitral Septal Myectomy for Hypertrophic Obstructive Cardiomyopathy in the Elderly

Background

The thoracoscopic trans-mitral approach can not only facilitate exposure of the ventricular septum, mitral valve, and subvalvular apparatus, it also enables the surgeons to perform concomitant mitral valve intervention. This study aimed to determine the safety and efficacy of thoracoscopic trans-mitral septal myectomy in elderly patients with hypertrophic obstructive cardiomyopathy (HOCM).

Methods

We reviewed the demographic to clinical characteristics and outcomes of patients who underwent thoracoscopic trans-mitral septal myectomy in our center between April 2019 and April 2021. The population was divided into a younger group (<60 years) and an elderly group (≥60 years).

Results

There were 46 and 20 patients in the younger and elderly groups, respectively. The majority of patients in the elderly group were female (39.1 vs. 80.0%, P < 0.01). Patients in the elderly group were more likely to be in New York Heart Association Class IV (2.2 vs. 80.0%, P < 0.01). The European System for Cardiac Operation Risk Evaluation II predicted mortality rates were significantly higher (3.97 ± 1.81 vs. 1.62 ± 0.86%, P < 0.01) in the elderly group. In the elderly group, a patient converted to median sternotomy due to left ventricular posterior free wall rupture following septal myectomy and mitral bioprosthetic valve replacement. The patient then underwent double-patch sandwich repair for rupture and mitral mechanical valve replacement and was eventually discharged. All patients in the elderly group were discharged, while one in the younger group died. No patient in the elderly group required permanent pacemaker implantation vs. one in the younger group. Patients in the elderly group were more likely to spend more time in the intensive care unit than those in the younger group (5.44 ± 5.80 days vs. 3.07 ± 2.72, P < 0.05). However, there was no significant intergroup difference in in-hospital mortality or complications. Importantly, the left ventricular outflow tract pressure gradient was significantly decreased from 96.15 ± 32.89 mmHg to 8.2 ± 3.42 mmHg with no residual obstruction in the elderly group. The interventricular septal thickness was significantly decreased from 19.73 ± 3.14 mm to 11.30 ± 2.23 mm. Postoperative mitral regurgitation severity was significantly improved in the elderly group.

Conclusion

This study demonstrated that thoracoscopic trans-mitral septal myectomy is a feasible option for selected elderly patients with satisfactory outcomes similar to those of young patients.

Video-Assisted Thoracoscopic Transaortic Myectomy for Hypertrophic Obstructive Cardiomyopathy

Hypertrophic obstructive cardiomyopathy remains one of the more common inherited cardiac disorders with often a major impact on quality of life. Even today, most frequently a sternotomy is performed to conduct the myectomy. Several minimally invasive procedures, under direct vision or through transmitral access, have been demonstrated to operate on these patients. However, we believe our video-assisted transaortic approach could provide a more precise and complete resection than other minimally invasive approaches because of a clearer visualization of the septum and outflow tract. This could further increase the benefits for these patients and potentially make more frail patients eligible for surgical intervention.

Minimally Invasive Versus Full-Sternotomy Septal Myectomy for Hypertrophic Cardiomyopathy

OBJECTIVE

Septal myectomy remains the criterion standard for the treatment of patients with hypertrophic obstructive cardiomyopathy refractory to medical therapy. There have been few reports of minimally invasive approaches. This study compared a minimally invasive septal myectomy performed at our institution with the traditional full-sternotomy approach.

METHODS

Patients receiving a stand-alone septal myectomy were retrospectively reviewed from November 1999 to December 2016 (N = 120). Patients were stratified by surgical approach: traditional full sternotomy (n = 34) and ministernotomy (n = 86). Preoperative and perioperative variables were compared as well as follow-up symptomatic and echocardiographic outcomes.

RESULTS

Both groups had a significant decrease in New York Heart Association class heart failure symptoms (P < 0.001). At a mean ± SD follow-up time of 2.0 ± 3.4 years, postoperative New York Heart Association class distribution was similar between ministernotomy and full sternotomy (P = 0.684). Follow-up resting left ventricular outflow tract gradient was also similar between ministernotomy and full sternotomy (11 mm Hg ± 15 vs 9 mm Hg ± 13, P = 0.381). Perioperatively, ministernotomy was not significantly different from full sternotomy in median cardiopulmonary bypass time (81 minutes vs 78 minutes, P = 0.101) but had a slightly longer median cross-clamp time (39 minutes vs 35 minutes, P = 0.017). Major complications were similar in the two groups. There was one 30-day mortality in the full-sternotomy group, but no in-hospital deaths.

CONCLUSIONS

Septal myectomy performed using a minimally invasive approach has similar outcomes to the criterion standard operation done through a full sternotomy. It represents a feasible option for patients with hypertrophic obstructive cardiomyopathy unresponsive to medications.

Minimally Invasive Septal Myectomy for Hypertrophic Obstructive Cardiomyopathy

Surgical septal myectomy is the treatment of choice for patients with symptomatic hypertrophic obstructive cardiomyopathy refractory to medications. This report describes our minimally invasive approach for performing a septal myectomy via a ministernotomy that has been used at our institution for more than a decade. In particular, patient preparation, surgical technique, and clinical considerations are highlighted. Performed properly, this minimally invasive technique is a feasible and effective approach in our experience.

Surgical treatment for hypertrophic cardiomyopathy: a historical perspective

Our understanding of hypertrophic cardiomyopathy (HCM) as a disease entity has increased dramatically over the last half century. There has been a concerted effort by several surgical groups to develop operative techniques to relieve left ventricular outflow tract (LVOT) obstruction and alleviate symptoms. This paper traces the development of transaortic septal myectomy, the current gold standard therapy for relief of LVOT obstruction, in symptomatic patients refractory to medical treatment. In addition, we introduce newer methods for myectomy that have expanded the role of surgery in patients with various forms of HCM.