Apical myectomy for patients with hypertrophic cardiomyopathy and advanced heart failure

Apical hypertrophic cardiomyopathy: pathophysiology, diagnosis and management

Since the first description of apical hypertrophic cardiomyopathy (ApHCM) in 1976, contrasting information from all over the world has emerged regarding the natural history of the disease. However, the recommended guidelines on hypertrophic cardiomyopathy (HCM) pay a cursory reference to ApHCM, without ApHCM-specific recommendations to guide the diagnosis and management. In addition, cardiologists may not be aware of certain aspects that are specific to this disease subtype, and a robust understanding of specific disease features can facilitate recognition and timely diagnosis. Therefore, the review covers the incidence, pathogenesis, and characteristics of ApHCM and imaging methods. Echocardiography and cardiovascular magnetic resonance imaging (CMR) are the most commonly used imaging methods. Moreover, this review presents the management strategies of this heterogeneous clinical entity. In this review, we introduce a novel transapical beating-heart septal myectomy procedure for ApHCM patients with a promising short-time result.

Efficacy and safety of a transaortic approach to midventricular and apical septal myectomy

OBJECTIVE

The study objective was to evaluate the safety and efficacy of a transaortic approach to midventricular and apical septal myectomy in patients with hypertrophic cardiomyopathy with left ventricular outflow tract or midventricular obstruction.

METHODS

From January 2018 to August 2023, 940 patients underwent transaortic septal myectomy at the Cleveland Clinic, of whom 682 (73%) had midventricular or apical resection. Patients who underwent isolated basal myectomies were excluded. Templated operative reports designated septal regions resected as basal (opposition to mitral valve up to the leaflet tips), midventricular (leaflet tips to just beyond the papillary muscle heads), and apical (apical third of the ventricle). Myocardial resection specimen weights, intraventricular gradients, and clinical outcomes were assessed.

RESULTS

Of the 682 patients, 582 (85%) had basal plus midventricular resection and 78 (11%) had basal, midventricular, and apical resection. Mean preoperative intraventricular gradient was 102 ± 41 mm Hg. Median resection weight was 10 g (15th, 85th percentiles: 7, 15), and mean postoperative intraventricular gradient was 16 ± 10 mm Hg, with 625 (96%) patients achieving gradients 36 mm Hg or less. There were no iatrogenic mitral or aortic valve injuries. Permanent pacemaker placement was required in 38 patients (5.6%), of whom 8 (1.2%) had normal preoperative conduction. Operative mortality occurred in 1 patient (0.1%) after an intraoperative ventricular septal defect.

CONCLUSIONS

Most patients undergoing septal myectomy for relief of obstruction required resection beyond the basal septum. With specialized instrumentation, detailed imaging and knowledge of variable septal anatomy, resecting midventricular and apical septal muscle can be safely and effectively achieved through a transaortic approach.

Treatment Strategies for Hypertrophic Cardiomyopathy: Surgical

Septal myectomy is a well-established procedure for septal reduction in patients with obstructive hypertrophic cardiomyopathy (HCM) who have not responded to medical treatment. The surgical approach is tailored to the unique pathophysiology and septal morphology of the patient. Extended transaortic myectomy is the standard procedure for patients with isolated subaortic obstruction, the most common type of HCM. However, transapical myectomy is a useful adjunct for patients with long or midventricular obstruction and is our preferred technique for ventricular enlargement in patients with severe symptomatic diastolic heart failure because of extensive apical hypertrophy. Septal myectomy provides excellent postoperative outcomes as regards symptom relief and functional improvement, and operative morbidity and mortality rates are low in experienced centers. This article summarizes our current surgical management of patients with HCM and details operative methods and outcomes.

Contemporary Surgical Management of Hypertrophic Cardiomyopathy

More than half of symptomatic patients with hypertrophic cardiomyopathy (HCM) have left ventricular outflow tract (LVOT) obstruction. Septal reduction therapy by septal myectomy can dramatically relieve exertional dyspnea, chest pain, and presyncope in properly selected patients and is an important management pathway for many patients. The distribution and degree of hypertrophy in patients with obstructive HCM are variable and, as discussed in this review, can influence clinical manifestations of the disease and surgical management. Subaortic septal hypertrophy is the most common phenotype of obstructive HCM associated with LVOT obstruction, but midventricular obstruction and apical hypertrophy may occur in isolation or in conjunction with subaortic septal hypertrophy. In many comprehensive HCM centers, transaortic septal myectomy is the preferred method of septal reduction therapy for symptomatic patients with obstructive HCM. Early surgical approaches aimed at alleviating left LVOT obstruction were hampered by a lack of understanding of the anatomy and pathophysiology of obstructive HCM. With the advent of Doppler echocardiography and, more recently, cardiac magnetic resonance imaging, surgeons can precisely assess the location and degree of obstruction, left ventricular size and function, and morphology and function of the mitral valve. This review discusses the current understanding of the role of septal myectomy in the management of patients with HCM and details contemporary operative methods.

Transapical Approach to Septal Myectomy for Hypertrophic Cardiomyopathy

A 63-year-old symptomatic female with apical hypertrophic cardiomyopathy and diastolic disfunction was admitted to the hospital. What is the best way to manage this patient? This study is a literature review that was performed to answer this question. The following PubMed search strategy was used: 'Hypertrophic obstructive cardiomyopathy' [All Fields] OR 'apical myectomy' [All Fields], NOT 'animal [mh]' NOT 'human [mh]' NOT 'comment [All Fields]' OR 'editorial [All Fields]' OR 'meta-analysis [All Fields]' OR 'practice-guideline [All Fields]' OR 'review [All Fields]' OR 'pediatrics [mh]'. The natural history of the disease has a benign prognosis; however, a watchful strategy was associated with the risk of adverse cardiovacular events. Contrastingly, transapical myectomy was associated with low surgical risk and acceptable outcomes. In our case, the patient underwent transapical myectomy with an unconventional post-operative period. Control echocardiography showed marked left ventricular (LV) cavity enlargement: LV end-diastolic volume, 74 mL; LV ejection fraction, 65%; and LV stroke volume index increased to 27 mL/m2. The patient was discharged 7 days after myectomy. At 6 months post-operation, the patient was NYHA Class I, with a 6 min walk test score of 420 m. Therefore, transapical myectomy may be considered as a feasible procedure in patients with apical hypertrophic cardiomyopathy and progressive heart failure.

Analysis and evaluation of patient-specific three-dimensional printing in complex septal myectomy

OBJECTIVES

This study aimed to assess the effectiveness of three-dimensional printing (3DP) in patients with complex hypertrophic cardiomyopathy requiring combined transaortic and transapical septal myectomy.

METHODS

We created 3DP models for 7 patients undergoing this surgery approach between June and October 2022 using silicone-like resin and conducted mock operations. The models were compared with echocardiography to identify abnormal muscle bundles and heart structures. These patients were then compared with a 1:2 matched group without 3DP, considering age, sex and additional operations.

RESULTS

The models mostly presenting with midventricular obstruction showed high consistency with original computed tomography data (r = 0.978, P < 0.001). 3DP identified more abnormal muscle bundles than echocardiography, primarily between the interventricular septum and apex. Excised specimens in mock operations mirrored those in actual myectomies. While cardiopulmonary bypass time was not significantly different, a near-20-min decrease was observed in the 3DP group (135.5 ± 31.1 vs 154.4 ± 36.6 min, P = 0.054).

CONCLUSIONS

While no significant differences in surgical outcomes were observed, 3DP appeared to enhance the visualization and understanding of spatial structures (average Likert scale score 4.0), potentially contributing to surgical proficiency (overall rating score 3.9). The use of 3DP may offer additional value in the preparation and execution of operations for complex hypertrophic cardiomyopathy cases.

Invasive therapies for symptomatic obstructive hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a genetic condition with multiple different genetic and clinical phenotypes. As awareness for HCM increases, it is important to also be familiar with potential treatment options for the disease. Treatment of HCM can be divided into two different categories, medical and interventional. Typically for obstructive forms of the disease, in which increased septal hypertrophy, abnormally placed papillary muscles, abnormalities in mitral valve or subvalvular apparatus, lead to dynamic left ventricular outflow tract (LVOT) obstruction, treatment is targeted at decreasing obstructive gradients and therefore symptoms. Medications like beta blockers, calcium channel blockers, disopyramide can often accomplish this. However, in patients with severe obstruction or symptoms refractory to medical therapy, either surgical correction of the LVOT obstruction or percutaneous via alcohol septal ablation, are treatment options. In this review, we will focus on the invasive treatment of hypertrophic obstructive cardiomyopathy.

Apical Hypertrophic Cardiomyopathy Prompting Aneurysm, Thrombus, and Cardiac Arrest in a 56-Year-Old Female

Hypertrophic cardiomyopathy (HCM) is the most prevalent genetic cardiac disease while apical hypertrophic cardiomyopathy (apHCM) is a rare subset of HCM. The significance of this case report is to present apHCM, its chronological course, and its association with left ventricular aneurysm, thrombosis, and cardiac arrest. We present the case of a 56-year-old female with a past medical history of apHCM who was admitted for substernal chest pain, developed a ventricular storm (VT), and subsequently suffered cardiac arrest; resuscitation of spontaneous circulation (ROSC) was eventually achieved after 10 minutes. It was initially thought that her arrhythmia and hemodynamic decompensation were purely secondary to cocaine use at a party six hours prior to her presentation. During hospitalization, cardiac magnetic resonance imaging demonstrated a severe apHCM apical aneurysm, thrombosis, and a re-entrant circuit as a likely cause of this patient’s decompensation and eventual cardiac arrest. After several days of hemodynamic stability and decreased dependence on intravenous antiarrhythmic medication infusions, she was extubated and transitioned to oral amiodarone and beta-blocker therapy with the implantation of a cardioverter-defibrillator (ICD). In this case, we analyze the continuum of apHCM, a rare subset of HCM once thought to be benign but with the emergence of complications, including aneurysm, thrombus formation, resistant ventricular tachycardia, and cardiac arrest. Recognition and management of apHCM with medical and/or surgical intervention are therefore critical to prevent the aforementioned sequela.

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.

Left Ventricular Hypertrophy: Etiology-Based Therapeutic Options

Determining the etiologies of left ventricular hypertrophy (LVH) can be challenging due to the similarities of the different manifestations in clinical presentation and morphological features. Depending on the underlying cause, not only left ventricular mass but also left ventricular cavity size, or both, may increase. Patients with LVH remain asymptomatic for a few years, but disease progression will lead to the development of systolic or diastolic dysfunction and end-stage heart failure. As hypertrophied cardiac muscle disrupts normal conduction, LVH predisposes to arrhythmias. Distinguishing individuals with treatable causes of LVH is important for prevention of cardiovascular events and mortality. Athletic's heart with physiological LVH does not require treatment. Frequent causes of hypertrophy include etiologies due to pressure/volume overload, such as systemic hypertension, hypertrophic cardiomyopathy, or infiltrative cardiac processes such as amyloidosis, Fabry disease, and sarcoidosis. Hypertension and aortic valve stenosis are the most common causes of LVH. Management of LVH involves lifestyle changes, medications, surgery, and implantable devices. In this review we systematically summarize treatments for the different patterns of cardiac hypertrophy and their impacts on outcomes while informing clinicians on advances in the treatment of LVH due to Fabry disease, cardiac amyloidosis, and hypertrophic cardiomyopathy.

Transapical Ventricular Remodeling for Hypertrophic Cardiomyopathy With Systolic Cavity Obliteration

BACKGROUND

Some patients with hypertrophic cardiomyopathy (HCM) present with reduced left ventricular (LV) stroke volume and elongated systolic cavity obliteration due to symmetric LV hypertrophy. In this report, we detail our experience with transapical septal myectomy to enlarge the LV volume and to relieve cavity obliteration in this unique subgroup of patients with HCM.

METHODS

We analyzed 38 patients with HCM who had extended symmetric LV hypertrophy and underwent transapical septal myectomy to enlarge the LV cavity from February 2001 to May 2021.

RESULTS

At the time of evaluation for operation, 84.2% (n = 32) of the patients were in New York Heart Association class III/IV. The peak oxygen consumption was 51.5% (44.0%-58.0%) of the normal predicted values on the preoperative exercise stress test (n = 16). Preoperative left atrial sizes in this cohort were enlarged (left atrial volume index, 39.0 [33.5-51.5] mL/m²), despite only 4 patients with moderate or greater mitral valve regurgitation. All patients underwent transapical septal myectomy to enlarge the LV cavity size. There was no postoperative (within 30 days) death. During a median (interquartile range) follow-up of 3.4 (0.7-6.9) years, the estimated survival rates were 100%, 92%, and 87% at 1, 3, and 5 years, respectively. Follow-up surveys suggested that 16 of the 17 contacted patients experienced improvement in their heart function after the procedure.

CONCLUSIONS

Transapical myectomy to enlarge LV cavity volume can be performed safely with good early survival and functional results. This procedure is an important alternative to cardiac transplantation for HCM patients with systolic cavity obliteration and progressive heart failure.

Transapical septal myectomy for hypertrophic cardiomyopathy, an experience from Japan

BACKGROUND

While there are a variety of surgical options for hypertrophic cardiomyopathy, there are small number of reports of transapical septal myectomy. Furthermore, the characteristics and incidence of anomalous structures in the left ventricle in hypertrophic cardiomyopathy patients which can be identified with imaging studies are not clear.

METHODS

We studied hypertrophic cardiomyopathy patients who underwent transapical septal myectomy from July 2013 to December 2019. We evaluated the frequency and characteristics of anomalous structures in the left ventricle which had been identified by preoperative examinations and studied their postoperative results.

RESULTS

A total of 59 patients was included. The median age was 40 years. Sixteen patients (27.4%) were in New York Heart Association Functional Classification III or IV. The median peak intraventricular gradient at rest was 65 mmHg. By preoperative imaging studies, anomalous structures were detected in 56 cases (94.9%), of which 88% were successfully resected with myectomy. There were two perioperative deaths, while one late death caused by acute myocardial infarction occurred. The estimated 5-year survival rate was 95%. The intraventricular gradient had significantly decreased at the time of discharge, and no reoperation for recurrent obstruction was conducted. The left ventricular ejection fraction had significantly decreased after the operation, was however within the normal range. Left atrium volume index and tricuspid regurgitant velocity significantly improved.

CONCLUSIONS

Patients receiving transapical septal myectomy restored good hemodynamics from early postoperative period and showed improved subjective symptoms and good mid-term results. With multimodal imaging studies, we could accurately identify anomalous structures in hypertrophic cardiomyopathy patients and reliably treat them by transapical septal myectomy.

How to build a successful hypertrophic cardiomyopathy team and ensure training the next generation of myectomy surgeons

Transaortic extended septal myectomy is the most reliable method for septal reduction for symptomatic patients with obstructive hypertrophic cardiomyopathy. In addition, surgical management of nonobstructive hypertrophic cardiomyopathy is possible for selected patients with diastolic heart failure and small left ventricular end-diastolic cavity dimensions. These procedures, however, are performed infrequently in many centers, and trainees may not be exposed to the preoperative evaluation and intraoperative management of patients with hypertrophic cardiomyopathy. In this paper, we review what we believe are the central features for creating a successful program for septal myectomy and detail our strategies to optimize instruction in these techniques for residents and fellows.

[Surgical approaches to interventricular septum in hypertrophic cardiomyopathy]

Hypertrophic cardiomyopathy (HCM) is a hereditary myocardial disease characterized by ventricular wall and interventricular septum thickening not associated with heart valve disease or any other external cause. Considering different localization of left ventricular obstruction, surgeons should be aware of various surgical approaches to various segments of interventricular septum. A personalized approach to each patient is essential to achieve favorable postoperative effect with minimal incidence of complications. This review is devoted to various surgical approaches to interventricular septum for different phenotypic variants of HCM.

Unmet needs in the treatment of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a complex heterogeneous cardiovascular disorder characterized by hypertrophied and disorganized myocytes with varying degrees of interstitial fibrosis. The current management strategies include genetic and familial screening, symptom control and prevention of sudden cardiac death in those at high risk. Until recently, septal reduction therapy and heart transplantation were the only disease modifying treatments available to manage HCM, but emerging pharmacotherapies show promising results in controlled clinical trials. In this article, we will review the unmet needs in the treatment of HCM incorporating novel therapies.

A Case Report on Diagnostic Approach of a Complex Clinical Scenario: Differentiation Between Coronary Artery Disease and Apical Hypertrophic Cardiomyopathy as a Cause of Recurrent Debilitating Angina

Apical hypertrophic cardiomyopathy (ApHCM) is a clinical challenge when presenting with symptoms of angina plus shortness of breath. An appropriate diagnosis of concurrent coronary artery disease (CAD) is needed for proper diagnosis, risk stratification, and management. We present a case of a 64-year-old gentleman with a history of ApHCM and CAD with previous percutaneous intervention presenting with recurrent angina. A repeat coronary angiography showed no new obstructive lesions. A stress cardiac magnetic resonance imaging was performed, which showed perfusion defect in the apex with apical scarring likely secondary to microvascular disease. The patient was managed medically with the improvement of symptoms. Diagnosis and management of CAD in patients with ApHCM are challenging. Multiple diagnostic modalities may be required for delineating the underlying pathology. Patients should be managed initially with medications. If symptoms are not controlled with medical management, a heart team approach with referral to an advanced center experienced in apical myectomy should be considered.

Novel Resectable Myocardial Model Using Hybrid Three-Dimensional Printing and Silicone Molding for Mock Myectomy for Apical Hypertrophic Cardiomyopathy

Objective

We implemented a novel resectable myocardial model for mock myectomy using a hybrid method of three-dimensional (3D) printing and silicone molding for patients with apical hypertrophic cardiomyopathy (ApHCM).

Materials and Methods

From January 2019 through May 2020, 3D models from three patients with ApHCM were generated using the end-diastolic cardiac CT phase image. After computer-aided designing of measures to prevent structural deformation during silicone injection into molding, 3D printing was performed to reproduce anatomic details and molds for the left ventricular (LV) myocardial mass. We compared the myocardial thickness of each cardiac segment and the LV myocardial mass and cavity volumes between the myocardial model images and cardiac CT images. The surgeon performed mock surgery, and we compared the volume and weight of the resected silicone and myocardium.

Results

During the mock surgery, the surgeon could determine an ideal site for the incision and the optimal extent of myocardial resection. The mean differences in the measured myocardial thickness of the model (0.3, 1.0, 6.9, and 7.3 mm in the basal, midventricular, apical segments, and apex, respectively) and volume of the LV myocardial mass and chamber (36.9 mL and 14.8 mL, 2.9 mL and −9.4 mL, and 6.0 mL and −3.0 mL in basal, mid-ventricular and apical segments, respectively) were consistent with cardiac CT. The volume and weight of the resected silicone were similar to those of the resected myocardium (6 mL [6.2 g] of silicone and 5 mL [5.3 g] of the myocardium in patient 2; 12 mL [12.5 g] of silicone and 11.2 mL [11.8 g] of the myocardium in patient 3).

Conclusion

Our 3D model created using hybrid 3D printing and silicone molding may be useful for determining the extent of surgery and planning surgery guided by a rehearsal platform for ApHCM.

Management of Subaortic Left Ventricular Outflow Tract Obstruction After Aortic Valve Replacement

BACKGROUND

Residual or new left ventricular outflow tract (LVOT) obstruction after an aortic valve replacement poses special challenges with respect to operative techniques. Our study assesses this gap.

METHODS

From January 1993 to May 2019, 18 patients underwent a septal myectomy at Mayo Clinic for subaortic obstruction after aortic valve replacement. We evaluated their demographics, clinical presentation, and echocardiograms, and the type of prior valve replacement, need for repeat replacement, and their short- and long-term outcomes. The data were analyzed using descriptive statistics.

RESULTS

All patients underwent septal myectomy for LVOT obstruction at a median interval of 7 years (interquartile range, 3-15 years) from their prior aortic valve procedure. Preoperatively, the median left ventricular outflow tract gradient was 57 mm Hg (interquartile range, 44-77 mm Hg); 10 patients (55.5%) had systolic anterior motion (SAM) of the mitral leaflets. Repeat replacement of the aortic valve at the time of myectomy was needed in 14 patients, and septal myectomy alone was performed in 4 patients. One hospital death occurred 34 days after myectomy and aortic valve replacement, and 2 patients needed permanent pacemaker placement for complete heart block.

CONCLUSIONS

Septal myectomy after aortic valve replacement may be performed with repeat replacement of the valve, if there is coexisting prosthetic dysfunction, through a normally functioning bioprosthesis or through an apical approach when visualization through the aortic prosthesis is poor. The complexity of reoperation supports a liberal approach to myectomy at the time of aortic valve replacement when there is significant subaortic septal hypertrophy.

Nonobstructive Hypertrophic Cardiomyopathy in a Patient With Mitral Prosthesis

Transapical septal myectomy can be performed for patients with nonobstructive hypertrophic cardiomyopathy and diastolic dysfunction to enlarge the LV cavity. The procedure may also include limited shaving of severely hypertrophied papillary muscles. This report illustrates the usefulness of papillary muscle resection to enlarge the left ventricle in a patient with nonobstructive hypertrophic cardiomyopathy and preexisting mitral valve prosthesis.

Transapical Septal Myectomy for Hypertrophic Cardiomyopathy With Midventricular Obstruction

BACKGROUND

Midventricular obstruction (MVO) is an uncommon variant of hypertrophic cardiomyopathy (HCM). In patients receiving septal myectomy for HCM, failure to recognize the concurrent MVO in the context of basal septum thickening can lead to inadequate excision and residual gradient. In this report, we detail the operative outcomes of MVO with and without coexistent basal septal hypertrophy.

METHODS

From February 1997 through September 2018, 196 patients underwent midventricular myectomy. Medical records and follow-up databases were reviewed to obtain patient characteristics and perioperative features.

RESULTS

At baseline, 156 patients (80%) were in New York Heart Association Functional Classification III/IV. Obstruction was isolated to the midventricle in 80 patients, and 63 (79%) were treated by isolated transapical myectomy. The remaining 116 patients had intraventricular obstruction at both subaortic and midcavity levels; in 108 (93%), a combined transaortic and transapical approach was adopted to achieve complete relief of the obstruction. After septal myectomy, the resting peak instantaneous gradient decreased from a median 48 mm Hg (interquartile range [IQR], 23-77 mm Hg) preoperatively to 8 mm Hg (IQR, 0-19 mm Hg) before hospital dismissal. Median follow-up was 2.9 years (IQR, 0.7-5.0 years), and the estimated 1-, 5-, and 10-year survivals were 99%, 98%, and 90%, respectively. There were no late complications attributable to the transapical incision.

CONCLUSIONS

Transapical exposure is a safe and effective approach for relief of midventricular obstruction, and hemodynamic results are similar to those achieved by standard myectomy for subaortic obstruction. The technique can be combined with transaortic myectomy for patients with left ventricular outflow obstruction at both levels.