Outcomes Over Follow-up ≥10 Years After Surgical Myectomy for Symptomatic Obstructive Hypertrophic Cardiomyopathy

Hypertrophic Cardiomyopathy: From Medical Treatment to Advanced Heart Failure Therapies

PURPOSE OF REVIEW

There has been much debate surrounding novel medical therapies and heart transplantation listing challenges in patients with hypertrophic cardiomyopathy (HCM).

RECENT FINDINGS

Recent clinical trials led to FDA approval of mavacamten (a cardiac myosin inhibitor), offering symptom relief and potentially delaying/avoiding invasive septal reduction therapies for some patients with HCM and left ventricular outflow obstruction (LVOTO). For those with refractory symptoms and end-stage heart failure, heart transplantation remains the gold standard. However, the concern for the organ allocation system failing to prioritize those individuals persists. HCM is a heterogeneous genetic condition with variable penetration and clinical presentation. Even though a large portion of patients remain asymptomatic, an important minority develops debilitating symptoms refractory to medical therapy. Post-HT short- and long-term outcomes are favorable. However, HT waitlist mortality remains high. For highly selected patients with HCM, a left ventricular assist device is a viable option.

Outcomes after septal myectomy in a cohort of patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) with left ventricular outflow tract obstruction that doesn't improve with pharmacological management often requires septal myectomy. However, there are few centers with experience in the practice of this procedure in our country. We describe the clinical and echocardiographic characteristics and postoperative outcomes of patients with HCM indicated for septal myectomy at a reference center in Colombia.

MATERIALS AND METHODS

Retrospective cohort study. Patients undergoing septal myectomy between 2010 and 2023 were included. Data were collected before and two years after surgery.

RESULTS

18 patients were included. The mean age was 50 years. The predominant functional class was NYHA II/III (94 %). Asymmetric septal variant (83.3 %) was the most frequent as well as obstructive phenotype (88.8 %). After myectomy, 70.5 % improved to NYHA I and 62.4 % had no significant gradient (<30 mmHg), and the most of patient improved SAM. One patient died post-procedure, anymore complications were presented.

DISCUSSION/CONCLUSIONS

Septal myectomy is a safe procedure, with clinical and echocardiographic improvement, with low complication rates.

Midterm Outcomes: A Comprehensive Approach to Surgery for Hypertrophic Obstructive Cardiomyopathy

BACKGROUND

Left ventricular outflow tract (LVOT) obstruction in obstructive hypertrophic cardiomyopathy (HCM) is caused by a constellation of abnormalities. This study reviewed outcomes of a comprehensive approach to correct these abnormalities during surgery.

METHODS

This was a single-institution study of patients with HCM who underwent septal myectomy from 2016 to 2023. Their New York Heart Association functional classification and most recent echocardiogram that estimated LVOT gradient and mitral valve function were tracked.

RESULTS

The study included 103 patients with a mean age of 54 years (interquartile range, 40-67 years) and common comorbidities: hypertension (50%) and atrial fibrillation (25%). On average, the preprocedure resting echocardiogram showed an LVOT gradient of 36.4 mm Hg and moderate or severe mitral regurgitation in 50.5% of patients. All patients underwent septal myectomy, and associated abnormalities contributing to LVOT obstruction were addressed. Elongation of the anterior leaflet of the mitral valve was typically treated with papillary muscle realignment (72%). Aberrant papillary muscle heads and elongated secondary chordae tendineae contributing to systolic anterior motion were resected (66%). Myocardial bands, including apicoseptal bands contributing to LVOT obstruction, were resected (68%). With an average follow-up of 4 years, 91% of patients were considered to be in New York Heart Association functional class I or II. Long-term echocardiographic follow-up showed a mean peak LVOT gradient of 11 mm Hg (interquartile range, 4-13 mm Hg). Only 1 patient had more than mild mitral regurgitation.

CONCLUSIONS

A comprehensive surgical approach to HCM that addresses the entire constellation of abnormalities associated with HCM, including mitral valve anterior leaflet elongation, aberrant or displaced mitral valve subvalvular apparatus, and myocardial bands, leads to outstanding midterm outcomes.

Pulmonary hypertension associated with left heart disease

Left heart disease (LHD) is the most common cause of pulmonary hypertension (PH), which may be classified further as isolated post-capillary (ipcPH) or combined post- and pre-capillary PH (cpcPH). The 7th World Symposium on Pulmonary Hypertension PH-LHD task force reviewed newly reported randomised clinical trials and contemplated novel opportunities for improving outcome. Results from major randomised clinical trials reinforced prior recommendations against the use of pulmonary arterial hypertension therapy in PH-LHD outside of clinical trials, and suggested possible harm. Greater focus on phenotyping was viewed as one general strategy by which to ultimately improve clinical outcomes. This is potentially achievable by individualising ipcPH versus cpcPH diagnosis for patients with pulmonary arterial wedge pressure within a diagnostic grey zone (12-18 mmHg), and through a newly developed PH-LHD staging system. In this model, PH accompanies LHD across four stages (A=at risk, B=structural heart disease, C=symptomatic heart disease, D=advanced), with each stage characterised by progression in clinical characteristics, haemodynamics and potential therapeutic strategies. Along these lines, the task force proposed disaggregating PH-LHD to emphasise specific subtypes for which PH prevalence, pathophysiology and treatment are unique. This includes re-interpreting mitral and aortic valve stenosis through a contemporary lens, and focusing on PH within the hypertrophic cardiomyopathy and amyloid cardiomyopathy clinical spectra. Furthermore, appreciating LHD in the profile of PH patients with chronic lung disease and chronic thromboembolic pulmonary disease is essential. However, engaging LHD patients in clinical research more broadly is likely to require novel methodologies such as pragmatic trials and may benefit from next-generation analytics to interpret results.

Evaluation of mavacamten in patients with hypertrophic cardiomyopathy

AIMS

We aimed to comprehensively assess the safety and efficacy of mavacamten in hypertrophic cardiomyopathy (HCM) patients.

METHODS

A systematic review and meta-analysis was conducted, and efficacy [changes in postexercise left ventricular outflow tract (LVOT) gradient, left ventricular ejection fraction (LVEF), peak oxygen consumption (pVO 2 ), Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (KCCQ CSS), and the proportion of patients exhibiting an improvement of at least one New York Heart Association (NYHA) functional class from baseline)], safety (total count of treatment-emergent adverse events and SAEs, as well as the proportion of patients experiencing at least one adverse event or SAE), and cardiac biomarkers (NT-proBNP and cTnI) outcomes were evaluated.

RESULTS

We incorporated data from four randomized controlled trials, namely EXPLORER-HCM, VALOR-HCM, MAVERICK-HCM, and EXPLORER-CN. Mavacamten demonstrated significant efficacy in reducing the postexercise LVOT gradient by 49.44 mmHg ( P  = 0.0001) and LVEF by 3.84 ( P  < 0.0001) and improving pVO 2 by 0.69 ml/kg/min ( P  = 0.4547), KCCQ CSS by 8.11 points ( P  < 0.0001), and patients with at least one NYHA functional class improvement from baseline by 2.20 times ( P  < 0.0001). Importantly, mavacamten increased 1.11-fold adverse events ( P  = 0.0184) 4.24-fold reduced LVEF to less than 50% ( P  = 0.0233) and 1.06-fold SAEs ( P  = 0.8631). Additionally, mavacamten decreased NT-proBNP by 528.62 ng/l ( P  < 0.0001) and cTnI by 8.28 ng/l ( P  < 0.0001).

CONCLUSION

Mavacamten demonstrates both safety and efficacy in patients with HCM, suggesting its potential as a promising therapeutic strategy for this condition. Further research is warranted to confirm these results and explore its long-term effects.

Management of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is an important cause of heart failure and arrhythmias, including sudden death, with a major impact on the healthcare system. Genetic causes and different phenotypes are now increasingly being identified for this condition. In addition, specific medications, such as myosin inhibitors, have been recently shown as potentially able to modify its symptoms, hemodynamic abnormalities and clinical course. Our article aims to provide a comprehensive outline of the epidemiology, diagnosis and treatment of hypertrophic cardiomyopathy in the current era.

Interventions in Hypertrophic Obstructive Cardiomyopathy

Obstructive hypertrophic cardiomyopathy is the most common genetically transmitted cardiomyopathy that is associated with significant morbidity and mortality. Despite contemporary treatments and interventions, the management of patients with obstructive hypertrophic cardiomyopathy remains poorly defined compared with other branches of cardiology. In this review, we discuss established and novel therapeutic interventions in patients with obstructive hypertrophic cardiomyopathy with a focus on percutaneous and surgical strategies including surgical myectomy, mitral valve repair or replacement, percutaneous alcohol septal ablation, pacemaker and cardioverter-defibrillator implantation, septal embolization, radiofrequency endocardial catheter ablation, and percutaneous intramyocardial septal radiofrequency ablation.

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.

Advances in the Management of Hypertrophic Cardiomyopathy Leading to Low Disease-Related Mortality in 2023

Hypertrophic cardiomyopathy (HCM) is a relatively common often inherited heart disease encumbered throughout much of its almost 60-year history by the expectation of an unfavorable outcome with shortened longevity. However, it is notable that in 2023, most patients affected with HCM can now achieve normal or extended life expectancy without major disability because of a comprehensive constellation of management strategies that have evolved largely over the last 20 years. Distinct adverse disease pathways dictate high-benefit low-risk personalized treatments, without reliance on genomics and sarcomere mutations, including: primary prevention implantable defibrillators for sudden cardiac death prevention, surgical myectomy and percutaneous alcohol septal ablation to reverse heart failure symptoms, anticoagulation to prevent embolic stroke associated with concomitant atrial fibrillation, external defibrillation and hypothermia for out-of-hospital cardiac arrest, and heart transplant in a small patient subgroup with end-stage disease. Large cohort studies using these contemporary management strategies achieved remarkably low HCM-related mortality (0.5%/year) across all age groups, which is lower than in the other cardiac or noncardiac risks of living, and largely confined to nonobstructive patients with progressive heart failure, including those awaiting heart transplant.

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.

Left ventricular outflow tract obstruction in hypertrophic cardiomyopathy and the impact of mavacamten

Hypertrophic cardiomyopathy (HCM) is a common genetic disorder characterised by unexplained left ventricular hypertrophy. Left ventricular outflow tract obstruction is an integral component of the disease, often resulting in significant symptoms, but also carrying a risk of progression to heart failure and death. Advancements in our understanding of the pathophysiology of HCM have led to the development of new therapies targeting the molecular basis of the disease at the level of the cardiac sarcomere, the basic contractile apparatus of the myocardium. Myosin modulators are a novel class of small molecules which target cardiac myosins directly to modulate cardiac contractility. The myosin inhibitors present the first advancement in pharmacological management of obstructive HCM in almost 35 years, with a growing body of evidence for the safety, tolerability and efficacy of mavacamten, and to a lesser extent aficamten. The aim of this review is to summarise the current management of patients with obstructive HCM and review the most recent available data from clinical trials pertaining to myosin inhibition.

Ventricular Septal Myectomy for Obstructive Hypertrophic Cardiomyopathy (Analysis Spanning 60 Years Of Practice): AJC Expert Panel

Surgical myectomy remains the time-honored primary treatment for hypertrophic cardiomyopathy patients with drug refractory limiting symptoms due to LV outflow obstruction. Based on >50 years experience, surgery reliably reverses disabling heart failure by permanently abolishing mechanical outflow impedance and mitral regurgitation, with normalization of LV pressures and preserved systolic function. A consortium of 10 international currently active myectomy centers report about 11,000 operations, increasing significantly in number over the most recent 15 years. Performed in experienced multidisciplinary institutions, perioperative mortality for myectomy has declined to 0.6%, becoming one of the safest currently performed open-heart procedures. Extended myectomy relieves symptoms in >90% of patients by ≥ 1 NYHA functional class, returning most to normal daily activity, and also with a long-term survival benefit; concomitant Cox-Maze procedure can reduce the number of atrial fibrillation episodes. Surgery, preferably performed in high volume clinical environments, continues to flourish as a guideline-based and preferred high benefit: low treatment risk option for adults and children with drug refractory disabling symptoms from obstruction, despite prior challenges: higher operative mortality/skepticism in 1960s/1970s; dual-chamber pacing in 1990s, alcohol ablation in 2000s, and now introduction of strong negative inotropic drugs potentially useful for symptom management.

Alcohol Septal Ablation or Septal Myectomy? An Updated Systematic Review and Meta-Analysis of Septal Reduction Therapy for Hypertrophic Obstructive Cardiomyopathy

Objective

To evaluate the safety and effectiveness of alcohol septal ablation (ASA) and septal myectomy (SM) for the treatment of hypertrophic obstructive cardiomyopathy.

Methods

We searched the PubMed, MEDLINE, EMBASE, and CBM databases for observational research articles related to ASA and SM published from the establishment of the databases to November 2021. All ultimate selected articles were highly related to our target. The Newcastle-Ottawa Scale was used to evaluate the literature quality. A fixed or random effect model was performed in the meta-analysis depending on the heterogeneity of the included studies. The Mantel-Haenszelt test with relative risk ratio (RR) and 95% confidence interval (CI) was used to measure the effect indicator of binary data, while the inverse variance method with weighted mean difference (WMD) and 95% CI was used to measure the effect indicator of continuous data.

Results

A totally of 3,647 cases (1,555 cases treated with ASA and 2,092 cases treated with SM) were included. The results of the systematic review indicated no statistically significant difference in postoperative all-cause mortality (RR = 0.82; 95% CI: 0.65–1.04; P = 0.10) between patients treated with ASA and SM, but both the reduction in the postoperative left ventricular outflow tract pressure gradient (WMD = 9.35 mmHg, 95% CI: 5.38–13.31, P &lt; 0.00001) and the post-operative improvement on cardiac function, assessed by the grade of New York Heart Association (NYHA), compared to pre-operative measurements (WMD = 0.13; 95% CI: 0.00–0.26; P &lt; 0.04) in the ASA group were slightly inferior to those in the SM group. In addition, both the risk of pacemaker implantation (RR = 2.83, 95% CI: 2.06–3.88; P &lt; 0.00001) and the risk of reoperation (RR = 11.23, 95% CI: 6.21–20.31; P &lt; 0.00001) are recorded at a higher level after ASA procedure.

Conclusion

Both ASA and SM have a high degree of safety, but the reduction in the postoperative left ventricular outflow tract pressure gradient and the improvement on cardiac function are slightly inferior to SM. In addition, both the risk of pacemaker implantation and the risk of reoperation are recorded at a higher level after ASA procedure. The operative plan should be chosen through multidisciplinary discussions in combination with the wishes of the patients and the actual clinical situation.