Low Operative Mortality Achieved With Surgical Septal Myectomy

Canadian Cardiovascular Society Clinical Practice Update on Contemporary Management of the Patient With Hypertrophic Cardiomyopathy

Numerous guidelines on the diagnosis and management of hypertrophic cardiomyopathy (HCM) have been published, by learned societies, over the past decade. Although helpful they are often long and less adapted to nonexperts. This writing panel was challenged to produce a document that grew as much from years of practical experience as it did from the peer-reviewed literature. As such, rather than produce yet another set of guidelines, we aim herein to deliver a concentrate of our own experiential learning and distill for the reader the essence of effective and appropriate HCM care. This Clinical Practice Update on HCM is therefore aimed at general cardiologists and other cardiovascular practitioners rather than for HCM specialists. We set the stage with a description of the condition and its clinical presentation, discuss the central importance of "obstruction" and how to look for it, review the role of cardiac magnetic resonance imaging, reflect on the appropriate use of genetic testing, review the treatment options for symptomatic HCM-crucially including cardiac myosin inhibitors, and deal concisely with practical issues surrounding risk assessment for sudden cardiac death, and management of the end-stage HCM patient. Uniquely, we have captured the pediatric experience on our panel to discuss appropriate differences in the management of younger patients with HCM. We ask the reader to remember that this document represents expert consensus opinion rather than dogma and to use their best judgement when dealing with the HCM patient in front of them.

2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy" provides recommendations to guide clinicians in the management of patients with hypertrophic cardiomyopathy.

METHODS

A comprehensive literature search was conducted from September 14, 2022, to November 22, 2022, encompassing studies, reviews, and other evidence on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through May 23, 2023, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Hypertrophic cardiomyopathy remains a common genetic heart disease reported in populations globally. Recommendations from the "2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy" have been updated with new evidence to guide clinicians.

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.

2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy" provides recommendations to guide clinicians in the management of patients with hypertrophic cardiomyopathy.

METHODS

A comprehensive literature search was conducted from September 14, 2022, to November 22, 2022, encompassing studies, reviews, and other evidence on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through May 23, 2023, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Hypertrophic cardiomyopathy remains a common genetic heart disease reported in populations globally. Recommendations from the "2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy" have been updated with new evidence to guide clinicians.

Target population for a selective cardiac myosin inhibitor in hypertrophic obstructive cardiomyopathy: Real-life estimation from the French register of hypertrophic cardiomyopathy (REMY)

BACKGROUND

The efficacy of current pharmacological therapies in hypertrophic cardiomyopathy is limited. A cardiac myosin inhibitor, mavacamten, has recently been approved as a first-in-class treatment for symptomatic hypertrophic obstructive cardiomyopathy.

AIMS

To assess the profile and burden of cardiac myosin inhibitor candidates in the hypertrophic cardiomyopathy prospective Register of hypertrophic cardiomyopathy (REMY) held by the French Society of Cardiology.

METHODS

Data were collected at baseline and during follow-up from patients with hypertrophic cardiomyopathy enrolled in REMY by the three largest participating centres.

RESULTS

Among 1059 adults with hypertrophic cardiomyopathy, 461 (43.5%) had obstruction; 325 (30.7%) of these were also symptomatic, forming the "cardiac myosin inhibitor candidates" group. Baseline features of this group were: age 58±15years; male sex (n=196; 60.3%); diagnosis-to-inclusion delay 5 (1-12)years; maximum wall thickness 20±6mm; left ventricular ejection fraction 69±6%; family history of hypertrophic cardiomyopathy or sudden cardiac death (n=133; 40.9%); presence of a pathogenic sarcomere gene mutation (n=101; 31.1%); beta-blocker or verapamil treatment (n=304; 93.8%), combined with disopyramide (n=28; 8.7%); and eligibility for septal reduction therapy (n=96; 29%). At the end of a median follow-up of 66 (34-106) months, 319 (98.2%) were treated for obstruction (n=43 [13.2%] received disopyramide), 46 (14.2%) underwent septal reduction therapy and the all-cause mortality rate was 1.9/100 person-years (95% confidence interval 1.4-2.6) (46 deaths). Moreover, 41 (8.9%) patients from the initial hypertrophic obstructive cardiomyopathy group became eligible for a cardiac myosin inhibitor.

CONCLUSIONS

In this cohort of patients with hypertrophic cardiomyopathy selected from the REMY registry, one third were eligible for a cardiac myosin inhibitor.

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.

Evolving Strategies for the Management of Obstructive Hypertrophic Cardiomyopathy

For many years, treatment of hypertrophic cardiomyopathy (HCM) has focused on non-disease-specific therapies. Cardiac myosin modulators (ie, mavacamten and aficamten) reduce the pathologic actin-myosin interactions that are characteristic of HCM, leading to improved cardiac energetics and reduction in hypercontractility. Several recently published randomized clinical trials have demonstrated that mavacamten improves exercise capacity, left ventricular outflow tract obstruction and symptoms in patients with obstructive HCM and may delay the need for septal-reduction therapy. Long-term data in real-world populations will be needed to fully assess the safety and efficacy of mavacamten. Importantly, HCM is a complex and heterogeneous disease, and not all patients will respond to mavacamten; therefore, careful patient selection and shared decision making will be necessary in guiding the use of mavacamten in obstructive HCM.

Impact of concomitant surgical interventions on outcomes of septal myectomy in obstructive hypertrophic cardiomyopathy

BACKGROUND

Septal myectomy (SM) is offered to symptomatic patients with obstructive hypertrophic cardiomyopathy (oHCM) despite medical therapy. Frequently, patients undergo concomitant planned or ad-hoc mitral valve replacement (MVR), aortic valve replacement (SAVR), or coronary artery bypass grafting (CABG).

OBJECTIVES

We sought to assess characteristics and outcomes of patients with oHCM undergoing concomitant surgical interventions at the time of SM.

METHODS

The National Readmission Databases were used to identify all SM admissions in the United States (2010-2019). Patients undergoing SM were stratified into: isolated SM (±MV repair), SM + CABG only, SM + MVR, SM + SAVR, and SM + MVR + SAVR. Primary outcomes were in-hospital mortality, in-hospital adverse events, and 30-day readmission.

RESULTS

12,063 encounters of patients who underwent SM were included (56.1% isolated SM, 9.0% SM + CABG only, 17.5% SM + MVR, 13.1% SM + SAVR, and 4.3% SM + MVR + SAVR). Patients who underwent isolated SM were younger (54.3 vs. 67.1 years-old, p < 0.01) and had lower overall comorbidity burden. In-hospital mortality was lowest in isolated SM, followed by CABG only, SM + SAVR, SM + MVR, and SM + SAVR+MVR groups (2.3% vs. 3.7% vs. 5.3% vs. 6.7% vs. 13.7%, p < 0.01), respectively. SM with combined surgical interventions was associated with higher adverse in-hospital events (24.3% vs. 11.1%, p < 0.01) and 30-day readmissions (16.9% vs. 10.4%, p < 0.01). MV repair performed concomitantly with SM was not associated with increased in-hospital mortality (3.9% vs. 3.4%, p = 0.72; aOR 0.99; 95% CI: 0.54-1.80, p = 0.97]) or adverse clinical events.

CONCLUSIONS

In SM for oHCM, patients undergoing concomitant surgical interventions were characteristically distinct. Aside from MV repair, concomitant interventions were associated with worse in-hospital death, adverse in-hospital events, and 30-day readmission.

A systematic review and meta-analysis of the efficacy and safety of Mavacamten therapy in international cohort of 524 patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common heritable myocardial disorder worldwide. Current pharmacological treatment options are limited. Mavacamten, a first-in-class cardiac myosin inhibitor, targets the main underlying pathology of HCM. We conducted a systematic review and meta-analysis to evaluate the efficacy and safety of Mavacamten in patients with HCM. PRISMA flow chart was utilized using PubMed, SCOPUS, and Cochrane databases for all up-to-date studies using pre-defined keywords. Pre-specified efficacy outcomes comprised several parameters, including an improvement in peak oxygen consumption (pVO2) and ≥ 1 NYHA class, the need for septal reduction therapy (SRT), change from baseline in Kansas City Cardiomyopathy Questionnaire (KCCQ), changes in biochemical markers and LVEF, along with peak left ventricular outflow tract gradient at rest and after Valsalva maneuver. Safety outcomes included morbidity and serious adverse events. This systematic review included five studies, four RCTs and one non-randomized control trial comprised a total of 524 (Mavacamten [273, 54.3%] vs placebo [230, 45.7%] adult (≥ 18 years) patients with a mean age of 56 years. The study. comprised patients with Caucasian and Chinese ethnicity and patients with obstructive (oHCM) and non-obstructive (nHCM) HCM. Most baseline characteristics were similar between the treatment and placebo groups. Mavacamten showed a statistically significant increase in the frequency of the primary composite endpoint (RR = 1.92, 95% CI [1.28, 2.88]), ≥ 1 NYHA class improvement (RR = 2.10, 95% CI [1.66, 2.67]), a significant decrease in LVEF, peak left ventricular outflow tract gradient at rest and after Valsalva maneuver. Mavacamten also showed a significant reduction in SRT rates (RR = 0.29, 95% CI [0.21, 0.40], p < 0.00001), KCCQ clinical summary scores (MD = 8.08, 95% CI [4.80, 11.37], P < 0.00001) troponin levels and N-terminal pro-B-type natriuretic peptide levels. However, there was no statistically significant difference between Mavacamten and placebo regarding the change from baseline peak oxygen consumption. Mavacamten use resulted in a small increase in adverse events but no statistically significant increment in serious adverse events. Our study showed that Mavacamten is a safe and effective treatment option for Caucasian and Chinese patients with HCM on the short-term. Further research is needed to explore the long-term safety and efficacy of Mavacamten with HCM. In addition, adequately powered studies including patients with nHCM is needed to ascertain befits of Mavacamten in those patients.

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.

Treatment Strategies for Hypertrophic Cardiomyopathy: Alcohol Septal Ablation and Procedural Step-by-Step Technique

Alcohol septal ablation (ASA) is a well-established procedure for septal reduction therapy in patients with obstructive hypertrophic cardiomyopathy, significant at rest or provocable outflow tract gradients, and medically refractory symptoms. This percutaneous approach to relief of obstruction and eventual cardiac remodeling involves the infusion of a small quantity of ethanol into an appropriately targeted septal artery that is feeding the basal septum to create an iatrogenic and controlled focal infarction. Early akinesia is followed by subsequent thinning and remodeling, which widens the outflow tract, reducing or eliminating the obstruction. Historically, the use of ASA was reserved primarily for high-risk surgical candidates; however, more contemporary data suggest similar outcomes in the short-term and long-term safety of the procedure and overall effectiveness in relieving obstructive symptoms when it is performed in broader populations at experienced centers. Therefore, the current guidelines published in 2020 support ASA as a class 1 indication, similar to its open-heart surgical counterpart, surgical myectomy, when no concomitant significant coronary or valve surgical indication exists. This article summarizes contemporary management of patients with hypertrophic cardiomyopathy who were selected for ASA and details procedural methods and outcomes.

Patient-specific computational fluid dynamics for hypertrophic obstructive cardiomyopathy

BACKGROUND

The heterogeneous morphologic and functional expression of hypertrophic obstructive cardiomyopathy (HOCM) is evidenced by established imaging, multimodality imaging is essential for a comprehensive assessment but may remain uncertain. This study aimed to develop a patient-specific hemodynamics assessment with cardiac computed tomography angiography (CCTA) based computational fluid dynamics (CFD) and prove its usability in cohorts of HOCM patients.

METHODS

A retrospective study was performed on eight HOCM patients with septal myectomy who had both preoperative and postoperative CCTA as well as transthoracic echocardiography (TTE). The three-dimensional models were reconstructed from CCTA data, following which patient-specific CFD simulations were performed to estimate the blood velocity, pressure gradient, and wall shear stress. The simulation output was compared with TTE. Based on CFD simulations, retrospective and blinded virtual myectomy was also performed, to predict the minimum resected volume for improving obstruction in patients.

RESULT

The complex HOCM anatomy was successfully reconstructed for all 8 patients. The CFD simulation accurately assessed the pressure gradient, flow velocity. There was a good correlation between the peak pressure gradient measured by CFD and TTE in the pre- and post-operative assessments (r = 0.87 and 0.84, respectively), and the flow velocity (r = 0.87 and 0.90, respectively). The volumes of minimal resection myocardium predicted by CFD and virtual myectomy were consistent with the actual resection volumes.

CONCLUSION

CCTA-based CFD for HOCM patients may play a unique role in the assessment of patient-specific morphology and hemodynamics. Combination with virtual myectomy might allow for optimizing therapy planning in septal myectomy.

CLINICAL PERSPECTIVE

CFD based CCTA may emerge as a complement to established imaging strategies, with accurate three-dimensional reconstruction and hemodynamic simulation of the left ventricle in this retrospective study. Combined with virtual myectomy, CFD simulation might allow for predicting the volume of resected myocardium for septal myectomy. Moving forward, this technology may be used by clinicians to better assess the conditions of HOCM patients, and guide the extent and depth of resection during septal myectomy. Therefore, further prospective clinical evaluation is clearly warranted.

Age-Based Outcomes in Patients Who Underwent Septal Reduction Therapy

There are no national data on age-based outcomes of septal reduction therapy. Using the National Inpatient Sample, we included all adult patients who underwent septal myectomy (SM) or alcohol septal ablation (ASA) from 2005 to 2019. The primary objective was to evaluate the in-hospital mortality and new permanent pacemaker (PPM) placement after SM and ASA in 3 age groups. In total, 9,564 patients underwent SM and 5,084 underwent ASA. Compared with the age group 18 to 39 years, the odds of in-hospital mortality after SM were similar in age group 40 to 64 years and 4.46 times higher than in age group ≥65 years; the higher mortality in the older group was explained by higher co-morbidity burden on the risk-adjusted analysis. Furthermore, compared with age group 18 to 39 years, the odds of new PPM placement after SM were higher in the age groups 40 to 64 years and ≥65 years, despite the risk adjustment (adjusted odds ratio [AOR] 3.17, 95% confidence interval [CI] 1.33 to 7.58 and AOR 4.39, 95% CI 1.78 to 10.8, respectively). The odds of in-hospital mortality after ASA were similar in age groups 65 to 79 years and 18 to 64 years. However, the odds of in-hospital mortality were higher in the age group ≥80 years than in the age group 18 to 64 years, although this difference were not present after risk adjustment. The odds of new PPM after ASA were higher for the age groups 65 to 79 years and ≥80 years than age group 18 to 64 years, despite the risk adjustment (AOR 1.78, 95% CI 1.22 to 2.60 and AOR 3.10, 95% CI 2.09 to 6.57, respectively). Finally, we also estimated these absolute risks in different age groups. In conclusion, this national data will inform health care providers to better understand the aged-based risks of outcomes after septal reduction therapy.

Cardiac Myosin Inhibitors for Managing Obstructive Hypertrophic Cardiomyopathy: JACC: Heart Failure State-of-the-Art Review

Hypertrophic cardiomyopathy (HCM) is frequently caused by pathogenic variants in genes encoding sarcomere proteins and is characterized by left ventricular (LV) hypertrophy, hypercontractility, and-in many cases-left ventricular outflow tract (LVOT) obstruction. Despite standard management, obstructive HCM (oHCM) can still cause substantial morbidity, highlighting the critical need for more effective disease-specific therapeutic approaches. Over the past decade, improved understanding of the molecular pathobiology of HCM has culminated in development of cardiac myosin inhibitors (CMIs), a novel drug class that in recent randomized clinical trials has been shown to decrease LVOT obstruction, improve exercise capacity, and ameliorate symptom burden in patients with oHCM. Although promising, areas of uncertainty remain, including the long-term safety and efficacy of CMIs and whether they have the potential to modify progression of disease. Herein, we review key milestones in the clinical development of CMIs, contextualize CMIs with established oHCM therapies, and discuss future challenges and opportunities for the use of CMIs across the HCM spectrum.

Mavacamten, an Alternative to Septal Reduction Therapy for Patients with Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common heridetary cardiac disorder characterized by a wide range of symptoms. The pharmacological treatment of HCM is currently limited to beta blockers, non-dihydropyridine calcium channel blockers and disopyramide. Mavacamten is a novel cardiac myosin inhibitor, which was recently added to the limited pharmacological list of treatment options for HCM. This editorial elaborates on current evidence evaluating the use of mavacamten in patients with symptomatic obstructive HCM, comments on its current use and its expanded potential applications in the future.

Hospital Procedural Volume and Clinical Outcomes Following Septal Reduction Therapy in Obstructive Hypertrophic Cardiomyopathy

Background Prior national data showed a substantial in-hospital mortality in septal myectomy (SM) with an inverse volume-outcomes relationship. This study sought to assess the contemporary outcomes of septal reduction therapy and volume-outcome relationship in obstructive hypertrophic cardiomyopathy. Methods and Results All septal reduction therapy admissions between 2010 to 2019 in the United States were analyzed using the National Readmission Databases. Hospitals were stratified into tertiles of low-, medium-, and high-volume based on annualized procedural volume of alcohol septal ablation and SM. Of 19 007 patients with obstructive hypertrophic cardiomyopathy who underwent septal reduction therapy, 12 065 (63%) had SM. Two-thirds of hospitals performed ≤5 SM or alcohol septal ablation annually. In all SM encounters, 482 patients (4.0%) died in-hospital post-SM. In-hospital mortality was <1% in 1505 (88.4%) hospitals, 1% to 10% in 30 (1.8%) hospitals, and ≥10% in 167 (9.8%) hospitals. There were 63 (3.7%) hospitals (averaging 2.2 SM cases/year) with 100% in-hospital mortality. Post-SM (in low-, medium-, and high-volume centers, respectively), in-hospital mortality (5.7% versus 3.9% versus 2.4%, P=0.003; adjusted odds ratio [aOR], 2.86 [95% CI, 1.70-4.80], P=0.001), adverse in-hospital events (21.30% versus 18.0% versus 12.6%, P=0.001; aOR, 1.88 [95% CI, 1.45-2.43], P=0.001), and 30-day readmission (17.1% versus 12.9% versus 9.7%, P=0.001; adjusted hazard ratio, 1.53 [95% CI, 1.27-1.96], P=0.001) were significantly higher in low- versus high-volume hospitals. For alcohol septal ablation, the incidence of in-hospital death and all other outcomes did not differ by hospital volume. Conclusions In-hospital SM mortality was 4% with an inverse volume-mortality relationship. Mortality post-alcohol septal ablation was similar across all volume tertiles. Morbidity associated with SM was substantial across all volume tertiles.

Current and emerging pharmacotherapy for the management of hypertrophic cardiomyopathy

INTRODUCTION

Hypertrophic cardiomyopathy (HCM) is one of the most common genetic causes of heart disease. Since the initial description of HCM, there have been minimal strides in management options. Obstructive HCM constitutes a larger subset of patients with increased left ventricular outflow tract gradients causing symptoms. Septal reduction therapy (SRT) has been successful, but it is not the answer for all patients and is not disease modifying.

AREAS COVERED

Current guideline recommendations include beta-blockers, calcium channel blockers, or disopyramides for medical management, but there lacks evidence of much benefit with these drugs. In recent years, there has been the emergence of cardiac myosin inhibitors (CMI) which have demonstrated positive results in patients with both obstructive and non-obstructive HCM. In addition to CMIs, other drugs have been investigated as we have learned more about HCM's pathological mechanisms. Drugs targeting sodium channels and myocardial energetics, as well as repurposed drugs that have demonstrated positive remodeling are being investigated as potential therapeutic targets. Gene therapy is being explored with vast potential for the treatment of HCM.

EXPERT OPINION

The armamentarium of therapeutic options for HCM is continuously increasing with the emergence of CMIs as mainstays of treatment. The future of HCM treatment is promising.

Familial Hypertrophic Cardiomyopathy: Diagnosis and Management

Hypertrophic cardiomyopathy (HCM) is widely recognized as one of the most common inheritable cardiac disorders. Since its initial description over 60 years ago, advances in multimodality imaging and translational genetics have revolutionized our understanding of the disorder. The diagnosis and management of patients with HCM are optimized with a multidisciplinary approach. This, along with increased safety and efficacy of medical, percutaneous, and surgical therapies for HCM, has afforded more personalized care and improved outcomes for this patient population. In this review, we will discuss our modern understanding of the molecular pathophysiology that underlies HCM. We will describe the range of clinical presentations and discuss the role of genetic testing in diagnosis. Finally, we will summarize management strategies for the hemodynamic subtypes of HCM with specific emphasis on the rationale and evidence for the use of implantable cardioverter defibrillators, septal reduction therapy, and cardiac myosin inhibitors.

Old and new therapeutic solutions in the treatment of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a genetic disease of the myocardium that is relatively common in the general population, with an autosomal dominant inheritance as a genetic basis. Clinical and natural history pathways can be very different among patients with HCM. Treatment strategies have made very important advances in the last two decades, especially reducing cases of sudden death through effective risk stratification and the use of implantable defibrillators. Heart failure has become the predominant cause of morbidity and mortality in patients with HCM, being responsible for as many as 60% of disease-related deaths. HCM is most often characterized by the presence of left ventricular outflow tract (LVOT) obstruction, and this obstruction is the most frequent cause of impaired exercise tolerance in HCM and a strong independent predictor of heart failure progression and mortality. The different treatment strategies of LVOT obstruction in HCM are discussed below: surgical, invasive, and the more recent pharmacological.

Sudden cardiac death in childhood hypertrophic cardiomyopathy

The most prevalent cause of mortality in children with hypertrophic cardiomyopathy (HCM) is sudden cardiac death (SCD), which happens more frequently than in adult patients. Risk stratification tactics have generally been drawn from adult practice, however emerging data has revealed significant disparities between children and adult cohorts, implying the need for pediatric-specific risk stratification methodologies. We conducted an all-language literature search on Medline, Cochrane, Embase, and Google Scholar until October 2021. The following search strings and Medical Subject Heading (MeSH) terms were used: "HCM," "SCD," "Sudden Cardiac Death," and "Childhood Onset HCM." We explored the literature on the risk of SCD in HCM for its epidemiology, pathophysiology, the role of various genes and their influence, associated complications leading to SCD and preventive and treatment modalities. Childhood-onset HCM is linked to significant life-long morbidity and mortality, including a higher SCD rate in children than in adults. The present focus is on symptom relief and avoiding illness-related consequences, but the prospect of future disease-modifying medicines offers an intriguing opportunity to alter disease expression and outcomes in these young individuals. Current preventive recommendations promote implantable cardioverter defibrillator placement based on cumulative risk factor thresholds, although they have been demonstrated to have weak discriminating capacity. This article addresses questions and discusses the etiology, risk factors, and method to risk stratification for SCD in children with HCM.

Regional Disparities in the Use of Septal Reduction Therapy and Associated Outcomes in the United States (from a Real-World Database)

The regional differences in the use of septal reduction therapies and the associated outcomes in patients with Hypertrophic obstructive cardiomyopathy (HOCM) are unknown. The primary objective of our study was to evaluate the regional disparities in the use of septal reduction therapies, including septal myectomy and alcohol septal ablation, in patients with HOCM. The secondary objective was to analyze the regional differences in the outcomes in these patients. Patients with HOCM had 87% higher risk-adjusted odds of getting septal myectomy (adjusted odds ratio 1.87, p = 0.03) and 37% lower risk-adjusted odds of getting alcohol septal ablation (adjusted odds ratio 0.63, p = 0.03) in the Midwest than in the Northeast. The in-hospital mortality rate was higher for patients who underwent septal myectomy in the South versus the Northeast on the unadjusted analysis. These differences persisted despite the adjustment for demographic and clinical characteristics. Additional adjustment for hospital volume partially explained these disparities, but the adjustment for both hospital volume and hospital teaching status completely explained these disparities. The risk-adjusted in-hospital mortality in patients who underwent alcohol septal ablation was similar in the South versus other regions. In conclusion, regional disparities may exist in the use of septal myectomy and alcohol septal ablation, and patients with HOCM should be referred to high-volume teaching hospitals for septal myectomy for better outcomes, which may also eliminate the extra burden of hospital mortality in the South.

Dose-Blinded Myosin Inhibition in Patients With Obstructive Hypertrophic Cardiomyopathy Referred for Septal Reduction Therapy: Outcomes Through 32 Weeks

BACKGROUND

Septal reduction therapy (SRT) in patients with intractable symptoms from obstructive hypertrophic cardiomyopathy (oHCM) is associated with variable morbidity and mortality. The VALOR-HCM trial (A Study to Evaluate Mavacamten in Adults with Symptomatic Obstructive Hypertrophic Cardiomyopathy Who Are Eligible for Septal Reduction Therapy) examined the effect of mavacamten on the need for SRT through week 32 in oHCM.

METHODS

A double-blind randomized placebo-controlled multicenter trial at 19 US sites included patients with oHCM on maximal tolerated medical therapy referred for SRT with left ventricular outflow tract gradient ≥50 mm Hg at rest or provocation (enrollment, July 2020-October 2021). The group initially randomized to mavacamten continued the drug for 32 weeks, and the placebo group crossed over to dose-blinded mavacamten from week 16 to week 32. Dose titrations were based on investigator-blinded echocardiographic assessment of left ventricular outflow tract gradient and left ventricular ejection fraction. The principal end point was the proportion of patients proceeding with SRT or remaining guideline eligible at 32 weeks in both treatment groups.

RESULTS

From the 112 randomized patients with oHCM, 108 (mean age, 60.3 years; 50% men; 94% in New York Heart Association class III/IV) qualified for week 32 evaluation (56 in the original mavacamten group and 52 in the placebo cross-over group). After 32 weeks, 6 of 56 patients (10.7%) in the original mavacamten group and 7 of 52 patients (13.5%) in the placebo cross-over group met SRT guideline criteria or elected to undergo SRT. After 32 weeks, a sustained reduction in resting left ventricular outflow tract gradient (-33.0 mm Hg [95% CI, -41.1 to -24.9]) and Valsalva left ventricular outflow tract gradient (-43.0 mm Hg [95% CI, -52.1 to -33.9]) was observed in the original mavacamten group. A similar reduction in resting (-33.7 mm Hg [95% CI, -42.2 to -25.2]) and Valsalva (-52.9 mm Hg [95% CI, -63.2 to -42.6]) gradients was quantified in the cross-over group after 16 weeks of mavacamten. After 32 weeks, improvement by ≥1 New York Heart Association class was observed in 48 of 53 patients (90.6%) in the original mavacamten group and 35 of 50 patients (70%) after 16 weeks in the cross-over group.

CONCLUSIONS

In severely symptomatic patients with oHCM, 32 weeks of mavacamten treatment showed sustained reduction in the proportion proceeding to SRT or remaining guideline eligible, with similar effects observed in patients who crossed over from placebo after 16 weeks.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04349072.

Alcohol septal ablation versus surgical septal myectomy of obstructive hypertrophic cardiomyopathy: systematic review and meta-analysis

OBJECTIVES

To elucidate the optimal septal reduction therapy for obstructive hypertrophic cardiomyopathy, we conducted a meta-analysis comparing alcohol septal ablation (ASA) and septal myectomy.

METHODS

MEDLINE, EMBASE and Cochrane CENTRAL were searched to identify studies investigating the outcomes of ASA and septal myectomy in patients with obstructive hypertrophic cardiomyopathy in January 2023. The primary outcome of interest was all-cause mortality in studies with ≥1 year of follow-up. The secondary outcomes of interest comprised left ventricular outflow tract (LVOT) pressure gradient reduction and reoperations of LVOT. A subgroup analysis of all-cause mortality including studies with follow-up ≥5 years was performed.

RESULTS

27 observational studies were included (15 968 patients). Analysis demonstrated similar all-cause mortality [hazard ratio (HR) (95% confidence interval) (CI) 1.24 (0.88-1.76); P = 0.21; I2 = 56%]. In contrast, ASA was associated with less reduction of LVOT pressure gradient and a reoperation rate [weighted mean difference (95% CI) 11.04 mmHg (5.60-16.48); P < 0.01; I2 = 64%, HR (95% CI) 9.14 (6.55-12.75); P < 0.001; I2 = 0%, respectively]. The subgroup analysis with follow-up ≥5 years revealed higher long-term mortality with ASA [HR (95% CI) 1.50 (1.04-2.15); P = 0.03; I2 = 52%].

CONCLUSIONS

Although both septal reduction therapies were associated with similar all-cause mortality, ASA was associated with a higher rate of reoperation and less reduction of LVOT pressure gradient. Furthermore, all-cause mortality with follow-up ≥5 years showed favourable outcomes with septal myectomy, although the result is only hypothesis-generating given a subgroup analysis.

Impact of Hospital Volume on Outcomes of Septal Myectomy for Hypertrophic Cardiomyopathy

BACKGROUND

Left ventricular outflow tract obstruction is common among symptomatic patients with hypertrophic cardiomyopathy, yet septal reduction by surgical myectomy (septal myectomy [SM]) is performed infrequently in many centers. This study examined the possible relationship between institutional case volume and early outcomes of SM.

METHODS

The Society of Thoracic Surgeons Adult Cardiac Surgery Database was queried for patients with hypertrophic cardiomyopathy who underwent SM from January 2012 to December 2019. The study defined center case volume categories as <1, 1 to 4.99, 5 to 9.99, and ≥10 cases performed on average per year.

RESULTS

The study population included 5935 patients at 481 centers with 933 surgeons. The range of average center volume was <1 to 138 cases per year. Overall early mortality was 2.6%, ventricular septal defect (VSD) occurred in 1.9%, and complete heart block occurred in 9.0%. Concomitant mitral valve (MV) repair was performed in 28.7%, and MV replacement was performed in 17.1%. In multivariable analysis, the lowest annual case volume (average <1 case/y) was consistently associated with greater early mortality (odds ratio [OR], 5.4; CI, 3.0-9.9; P < .001), greater risk of VSD (OR, 9.3; CI ,4.2-20.4; P < .001), increased incidence of complete heart block (OR, 2.0; CI, 1.5-2.7; P < .001), and a higher likelihood of MV replacement (OR, 9.4; CI, 7.5-11.8; P < .001).

CONCLUSIONS

Volume of SM cases varies widely among institutions reporting to the Society of Thoracic Surgeons Adult Cardiac Surgery Database. There appears to be an important association between surgical experience, as reflected by institutional case volume, and early outcomes, including mortality, as well as the occurrence of VSD, heart block, and MV replacement.

Current and emerging perspectives on pathophysiology, diagnosis, and management of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetically inherited cardiomyopathy with an autosomal dominant inheritance pattern. A disease-causing gene is found between 34% and >60% of the times and the two most frequently mutated genes, which encode sarcomeric proteins, are MYBPC3 and MYH7. HCM is a diagnosis of exclusion since secondary causes of left ventricular hypertrophy should first be ruled out. These include hypertension, aortic stenosis, infiltrative disease, metabolic and endocrine disorders, mitochondrial cardiomyopathies, neuromuscular disorders, malformation syndromes and some chronic drug use. The disease is characterized by great heterogeneity of its clinical manifestations, however diastolic dysfunction and increased ventricular arrhythmogenesis are commonly seen. Current HCM therapies focus on symptom management and prevention of sudden cardiac death. Symptom management includes the use of pharmacological agents, elimination of medication promoting outflow track obstruction, control of comorbid conditions and invasive procedures, whereas in the prevention of sudden cardiac death, implantable cardiac defibrillators and antiarrhythmic drugs are used. A targeted therapy for LVOTO represented by allosteric cardiac myosin inhibitors has been developed. In terms of sport participation, a more liberal approach is recently recommended, after careful evaluation and common-shared decision. The application of the current therapies has lowered HCM mortality rates to <1.0%/year, however it appears to have shifted focus to heart failure and atrial fibrillation, as the predominant causes of disease-related morbidity and mortality and, therefore, unmet treatment need. With improved understanding of the genetic and molecular basis of HCM, the present decade will witness novel treatments for disease prevention and modification.

First-in-man application of Liwen RF™ ablation system in the treatment of drug-resistant hypertrophic obstructive cardiomyopathy

OBJECTIVES

This study sought to evaluate the clinical applicability of the Liwen Liu RF™ ablation system for percutaneous intramyocardial septal radiofrequency ablation (PIMSRA).

BACKGROUND

Data on new cardiac radiofrequency ablation devices for the treatment of hypertrophic obstructive cardiomyopathy (HOCM) are limited.

MATERIALS AND METHODS

From July 2019 to July 2020, a total of 68 patients with drug-resistant HOCM, who underwent PIMSRA with the Liwen RF™ ablation system, which has an ablation electrode of stepless adjustable length, were prospectively enrolled. Safety endpoints included, amongst others, the occurrence of pericardial effusion and/or hemorrhage, cardiac arrhythmias, device failure and procedural death. The reduction in left ventricular outflow tract (LVOT) gradients at 12 months follow-up were used as a surrogate marker for device efficacy.

RESULTS

All procedures were technically successful. The total energy output time of the system was 75.8 (IQR: 30.0) min, and the average power was 43.61 ± 13.34 watts. No ablation system error occurred. The incidence of pericardial effusion or hemorrhage, transient arrhythmia and resuscitation was 8.8, 39.7, and 1.5% during procedure, respectively. None of the patients died. During 30-day follow-up, there were no complications with the exception of a pericardial effusion in one patient (1.5%). No further complications were reported after 30 days. The patients' resting [baseline: 75 (IQR: 48) vs. 12-months: 12 (IQR: 19) mmHg, p < 0.001] and provoked [baseline: 122 (IQR: 53) vs. 12-months: 41 (IQR: 59) mmHg, p < 0.001] LVOT gradients decreased significantly during follow-up.

CONCLUSION

In this study, we demonstrate the safety and feasibility of the Liwen RF™ ablation system to treat HOCM. The system allows for significant and sustainable LVOT gradient reduction during 12-months of follow-up. Hence, the Liwen RF™ ablation system is a promising new device that has the potential to become an alternative to existing septal reduction concepts in HOCM patients.

Longitudinal Cost of Septal Myectomy Versus Alcohol Septal Ablation for Hypertrophic Cardiomyopathy

OBJECTIVE

To compare the postprocedural health care utilization and cost of septal myectomy (SM) and alcohol septal ablation (ASA).

PATIENTS AND METHODS

Using the OptumLabs Data Warehouse, we analyzed de-identified claims data of adult patients undergoing SM and ASA for obstructive hypertrophic cardiomyopathy from January 1, 2006, through December 31, 2018. We used propensity score weighting to compare the 2-year incidence rates of emergency department visits and rehospitalizations after SM and ASA.

RESULTS

We identified 953 patients in total: 660 underwent SM and 293 underwent ASA. There was no difference in the risk (odds ratio, 1.1; 95% CI, 0.6 to 1.8) or frequency (incidence rate ratio, 1.1; 95% CI, 0.8 to 1.5) of emergency department visits, but the annual risk of hospital readmission was 10.8% after SM and 25.9% after ASA during the second postoperative year (P=.004). In those who were ever readmitted, the average length of hospital stay within the first 2 years after ASA was 1.6 times as long as that after SM (incidence rate ratio, 1.6; 95% CI, 1.0 to 2.4). Overall, the 2-year cumulative postprocedural cost was significantly higher after ASA (P<.001).

CONCLUSION

Compared with ASA, SM is associated with fewer hospital readmissions and lower 2-year postprocedural health care cost.

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.

Septal Thickness Does Not Impact Outcome After Hypertrophic Obstructive Cardiomyopathy Surgery (Septal Myectomy and Subvalvular Mitral Apparatus Remodeling): A 15-Years of Experience

Background

The aim of this study was to assess the impact of septal thickness on long-term outcomes of surgical treatment for hypertrophic obstructive cardiomyopathy (HOCM) and correction of mitral subvalvular anomalies.

Methods

Sixty-six consecutive patients (58 ± 12 years, 56% female) undergoing extended septal myectomy and subvalvular mitral apparatus remodeling from 2007 to 2021 were retrospectively reviewed. Patients were divided into 2 groups according to septal thickness: moderate [< 18 mm, 29 patients (44%)] and severe [≥ 18 mm, 37 patients (56%)]. End points included survival, symptom improvement, reduction of left ventricle outflow tract (LVOT) gradient, resolution of mitral regurgitation (MR), and reoperation.

Results

The mean interventricular septal thickness was 19 ± 3 mm, 15.8 ± 0.8 mm in patients with moderate and 21.4 ± 3.2 mm in those with severe hypertrophy. Preoperative data, intraoperative variables, postoperative complication rates, pre-discharge echocardiographic and clinical parameters did not differ between the two study groups [except for procedures involving the posterior mitral leaflet (p = 0.033) and septal thickness after myectomy (p = 0.0001)]. Subvalvular apparatus remodeling (secondary chordae of mitral valve resection and papillary muscle and muscularis trabecula procedures including resection, splitting, and elongation) was invariably added to septal myectomy (100%). Four (6%) procedures involved the posterior mitral leaflets. Mitral valve replacement was carried out in two patients (3%, p = 0.4). Reoperation for persistent MR was necessary in one patient (1%, p = 0.4). Neither iatrogenic ventricular septal defect nor in-hospital mortality occurred. During follow-up (mean 4.8 ± 3.8 years), two deaths occurred. NYHA class was reduced from 2.9 ± 0.7 to 1.6 ± 0.6 (p < 0.0001), the LVOT gradient from 89.7 ± 34.5 to 16.3 ± 8.8 mmHg (p < 0.0001), mitral valve regurgitation grade from 2.5 ± 1 to 1.2 ± 0.5 (p < 0.0001), and septal thickness from 18.9 ± 3.7 to 13.9 ± 2.7 mm (p < 0.0001).

Conclusions

Regardless of septal thickness, subvalvular apparatus remodeling with concomitant septal myectomy can provide satisfactory long-term outcomes in terms of symptom improvement, LVOT obstruction relief, and MR resolution (without mitral valve replacement in most cases) in patients with HOCM.

Myosin Inhibition in Patients With Obstructive Hypertrophic Cardiomyopathy Referred for Septal Reduction Therapy

BACKGROUND

Septal reduction therapy (SRT), surgical myectomy or alcohol ablation, is recommended for obstructive hypertrophic cardiomyopathy (oHCM) patients with intractable symptoms despite maximal medical therapy, but is associated with morbidity and mortality.

OBJECTIVES

This study sought to determine whether the oral myosin inhibitor mavacamten enables patients to improve sufficiently to no longer meet guideline criteria or choose to not undergo SRT.

METHODS

Patients with left ventricular (LV) outflow tract (LVOT) gradient ≥50 mm Hg at rest/provocation who met guideline criteria for SRT were randomized, double blind, to mavacamten, 5 mg daily, or placebo, titrated up to 15 mg based on LVOT gradient and LV ejection fraction. The primary endpoint was the composite of the proportion of patients proceeding with SRT or who remained guideline-eligible after 16 weeks' treatment.

RESULTS

One hundred and twelve oHCM patients were enrolled, mean age 60 ± 12 years, 51% men, 93% New York Heart Association (NYHA) functional class III/IV, with a mean post-exercise LVOT gradient of 84 ± 35.8 mm Hg. After 16 weeks, 43 of 56 placebo patients (76.8%) and 10 of 56 mavacamten patients (17.9%) met guideline criteria or underwent SRT, difference (58.9%; 95% CI: 44.0%-73.9%; P < 0.001). Hierarchical testing of secondary outcomes showed significant differences (P < 0.001) favoring mavacamten, mean differences in post-exercise peak LVOT gradient -37.2 mm Hg; ≥1 NYHA functional class improvement 41.1%; improvement in patient-reported outcome 9.4 points; and NT-proBNP and cardiac troponin I between-groups geometric mean ratio 0.33 and 0.53.

CONCLUSIONS

In oHCM patients with intractable symptoms, mavacamten significantly reduced the fraction of patients meeting guideline criteria for SRT after 16 weeks. Long-term freedom from SRT remains to be determined. (A Study to Evaluate Mavacamten in Adults With Symptomatic Obstructive HCM Who Are Eligible for Septal Reduction Therapy [VALOR-HCM]; NCT04349072).

Transcatheter Myotomy to Relieve Left Ventricular Outflow Tract Obstruction: The Septal Scoring Along the Midline Endocardium Procedure in Animals

BACKGROUND

Left ventricular outflow tract obstruction complicates hypertrophic cardiomyopathy and transcatheter mitral valve replacement. Septal reduction therapies including surgical myectomy and alcohol septal ablation are limited by surgical morbidity or coronary anatomy and high pacemaker rates, respectively. We developed a novel transcatheter procedure, mimicking surgical myotomy, called Septal Scoring Along the Midline Endocardium (SESAME).

METHODS

SESAME was performed in 5 naive pigs and 5 pigs with percutaneous aortic banding-induced left ventricular hypertrophy. Fluoroscopy and intracardiac echocardiography guided the procedures. Coronary guiding catheters and guidewires were used to mechanically enter the basal interventricular septum. Imparting a tip bend to the guidewire enabled intramyocardial navigation with multiple df. The guidewire trajectory determined the geometry of SESAME myotomy. The myocardium was lacerated using transcatheter electrosurgery. Cardiac function and tissue characteristics were assessed by cardiac magnetic resonance at baseline, postprocedure, and at 7- or 30-day follow-up.

RESULTS

SESAME myotomy along the intended trajectory was achieved in all animals. The myocardium splayed after laceration, increasing left ventricular outflow tract area (753 to 854 mm², P=0.008). Two naive pigs developed ventricular septal defects due to excessively deep lacerations in thin baseline septa. No hypertrophy model pig, with increased septal thickness and left ventricular mass compared with naive pigs, developed ventricular septal defects. One animal developed left axis deviation on ECG but no higher conduction block was seen in any animal. Coronary artery branches were intact on angiography with no infarction on cardiac magnetic resonance late gadolinium imaging. Cardiac magnetic resonance chamber volumes, function, flow, and global strain were preserved. No myocardial edema was evident on cardiac magnetic resonance T1 mapping.

CONCLUSIONS

This preclinical study demonstrated feasibility of SESAME, a novel transcatheter myotomy to relieve left ventricular outflow tract obstruction. This percutaneous procedure using available devices, with a safe surgical precedent, is readily translatable into patients.

Transaortic Shallow Septal Myectomy and Cutting of Secondary Fibrotic Mitral Valve Chordae—A 5-Year Single-Center Experience in the Treatment of Hypertrophic Obstructive Cardiomyopathy

Background: Anomalies of the mitral apparatus have been shown to contribute to left ventricular outflow obstruction in patients with hypertrophic cardiomyopathy (HCM). We report our 5-year single-center experience with a shallow myectomy procedure associated with transaortic mitral valve repair in a cohort of HCM patients. Methods: We studied 83 consecutive patients who underwent surgical treatment of symptomatic left ventricular outflow obstruction. In all study patients, a transaortic shallow septal myectomy was performed. Fibrous or muscular structures connecting the papillary muscles to the septum or free wall were resected, and fibrotic secondary chordae of the anterior mitral valve were cut selectively. Results: We report one death (1.2%) during hospitalization, no iatrogenic ventricular septal defects, and two (2.4%) mitral valve replacements. At discharge, no patients were in New York Heart Association (NYHA) Class III/IV, from 49 (59%) preoperatively. Mean maximal septal thickness decreased from 24 ± 6 to 16 ± 3 mm. Mean outflow gradient decreased from 93 ± 33 to 13 ± 11 mmHg. Grade 3 or 4 mitral regurgitation was noticed in one patient postoperatively, from 32 (39%) before surgery. Conclusions: Shallow septal myectomy associated with secondary mitral valve chordal cutting and papillary muscle mobilization provided excellent results offering adequate treatment of outflow obstruction.

Survival Following Alcohol Septal Ablation or Septal Myectomy for Patients With Obstructive Hypertrophic Cardiomyopathy

BACKGROUND

There is little information regarding long-term mortality comparing the 2 most common procedures for septal reduction for obstructive hypertrophic cardiomyopathy (HCM), alcohol septal ablation (ASA), and septal myectomy.

OBJECTIVES

This study sought to compare the long-term mortality of patients with obstructive HCM following septal myectomy or ASA.

METHODS

We evaluated outcomes of 3,859 patients who underwent ASA or septal myectomy in 3 specialized HCM centers. All-cause mortality was the primary endpoint of the study.

RESULTS

In the study cohort, 585 (15.2%) patients underwent ASA, and 3,274 (84.8%) underwent septal myectomy. Patients undergoing ASA were significantly older (median age: 63.0 years [IQR: 52.7-72.8 years] vs 53.7 years [IQR: 44.9-62.8 years]; P < 0.001) and had smaller septal thickness (19.0 mm [IQR: 17.0-22.0 mm] vs 20.0 mm [IQR: 17.0-23.0 mm]; P = 0.007). Patients undergoing ASA also had more comorbidities, including renal failure, diabetes, hypertension, and coronary artery disease. There were 4 (0.7%) early deaths in the ASA group and 9 (0.3%) in the myectomy group. Over a median follow-up of 6.4 years (IQR: 3.6-10.2 years), the 10-year all-cause mortality rate was 26.1% in the ASA group and 8.2% in the myectomy group. After adjustment for age, sex, and comorbidities, the mortality remained greater in patients having septal reduction by ASA (HR: 1.68; 95% CI: 1.29-2.19; P < 0.001).

CONCLUSIONS

In patients with obstructive hypertrophic cardiomyopathy, ASA is associated with increased long-term all-cause mortality compared with septal myectomy. This impact on survival is independent of other known factors but may be influenced by unmeasured confounding patient characteristics.

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.

Hypertrophic Cardiomyopathy: New Concepts and Therapies

Hypertrophic cardiomyopathy (HCM), a relatively common, globally distributed, and often inherited myocardial disorder, transformed over the last several years into a treatable condition with the emergence of effective management options that alter natural history at all ages. Now available are a matured risk stratification algorithm selecting patients for prophylactic implantable defibrillators that prevent arrhythmic sudden death; low-risk, high-benefit surgical myectomy to reverse progressive heart failure symptoms due to left ventricular outflow obstruction; anticoagulation prophylaxis to prevent atrial fibrillation-mediated embolic stroke; and heart transplant for refractory end-stage disease in the absence of obstruction. Those strategies have resulted in reduction of HCM-related morbidity and reduction of mortality to 0.5% per year.

Is surgical myectomy challenged by emergence of novel drug therapy with mavacamten?

For 60 years, surgical myectomy has been the definitive treatment for symptomatic obstructive hypertrophic cardiomyopathy (HCM). Myectomy provides the opportunity to reverse heart failure symptoms in the vast majority of patient with low risk when performed in experienced centers and associated with extended longevity. More recently, a novel class of negative inotropic drug therapy with mavacamten has emerged offering expanded treatment options for obstructive HCM. In the recently completed phase III clinical trial, the EXPLORER-HCM about one-third of patients on mavacamten achieved the primary end-point of subjective symptomatic improvement and increased functional capacity assessed by peak VO₂. Of note, outflow gradients persistent in 43% of patients on mavacamten and 50% with symptoms consistent with NYHA class II or greater. A subset of patients also experienced significant reversible systolic dysfunction. Therefore, it is timely to place into perspective the potential role of mavacamten in context of the established low risk: high benefit of surgical myectomy for treatment of heart failure.

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

For over 50 years, surgical septal myectomy has been the preferred treatment for drug-refractory heart failure symptoms in obstructive hypertrophic cardiomyopathy (HCM). However, given the relatively youthful adult ages at which HCM surgery is usually performed, it is informative to evaluate longer-term results of myectomy after ≥10 years. We identified 139 consecutive obstructive HCM patients (50 ± 15 years of age; 55% men) who underwent surgical myectomy, 2003 to 2010 at Tufts HCM Center and followed 11.3 ± 2.7 years (range to 17). Operative mortality was low (0.6%) and left ventricular (LV) outflow gradients at rest were reduced from 56 ± 40 mm Hg preoperatively to 1 ± 7 mm Hg postoperatively, durable over the study period, with no patient requiring reoperation for the residual gradient. Over follow-up, 129 of 139 patients (93%) were alive ≥10 years after myectomy, including 17 patients ≥15 years. Of 118 patients with complete long-term clinical follow-up data, 109 (92%) experienced clinical improvement to New York Heart Association classes I or II. In 9 patients (8%) refractory class III/IV symptoms reoccurred 6.6 ± 3.9 years postoperatively, including 4 who ultimately underwent a heart transplant. After myectomy, there were 2 late HCM-related deaths, but none suddenly; notably 6 patients (12%) with prophylactic implantable cardioverter-defibrillators experienced appropriate therapy terminating ventricular tachycardia/ventricular fibrillation after myectomy. Survival following myectomy was 91% at 10 years (95% confidence interval: 85, 96%) not different from the age- and gender-matched general United States population (log-rank p = 0.64). In conclusion, myectomy provides permanent abolition of outflow gradients with reversal of heart failure and highly favorable long-term survival, representing a low-risk:high-benefit option when performed in experienced HCM centers. Myectomy did not protect absolutely against arrhythmic sudden death events, underscoring the importance of risk stratification in operative patients.

The first 200 septal myectomies: Ensuring gold standard outcomes

OBJECTIVES

Septal myectomy remains the gold standard treatment for symptomatic left ventricular outflow tract obstruction refractory to medical treatment. It is recommended that this operation be performed in dedicated hypertrophic obstructive cardiomyopathy centres by experienced surgeons. The septal myectomy option remains unavailable to many patients based solely on geography, including those who would clearly benefit more substantially from surgery than other therapeutic options. Here, we share our experience in starting new hypertrophic cardiomyopathy programmes.

METHODS

We retrospectively reviewed initial septal myectomy experiences at two hypertrophic cardiomyopathy programmes starting in 2014.

RESULTS

Two-hundred septal myectomies were performed. Mean age was 58.8 years and 51% were females. Advanced heart failure symptoms were present in 95.5% of patients and 23.5% had experienced syncope. Mean maximal intraventricular gradient was 89 mmHg and 48.5% underwent concomitant procedures at the time of septal myectomy. There was no perioperative (in-hospital or 30 days) mortality. Ninety-two per cent had provoked left ventricular gradients of ≤ 15 mmHg and 97% had none/mild mitral regurgitation at post-operative assessment. In our contemporary cohort, there were 2 (1%) intraoperative ventricular septal defects and 5% required a permanent pacemaker.

CONCLUSIONS

Our early septal myectomy experience targeted a complex population, frequently in need of concomitant procedures. Abolition of left ventricular obstruction and resolution of systolic anterior motion mediated mitral regurgitation can be expected. The safety and efficacy of septal myectomy carried at hypertrophic cardiomyopathy centres by properly trained surgeons achieved the desired outcomes established by recent hypertrophic cardiomyopathy guidelines.

Prognostic implications of different clinical profiles in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a myocardial genetic disease relatively common in the general population with heterogenous clinical presentation, natural history and prognosis. About 60% of HCM patients have a stable clinical course, while others may experience a variety of HCMrelated complications which follows relatively independent pathways, and that can be distinguished in different subgroups. These subgroups are represented by patients with left ventricular outflow tract obstruction; patients with end-stage disease and reduced or preserved systolic function; patients with apical hypertrophy; patients with apical aneurysm; patients with atrial fibrillation, patients at high risk of sudden death and patients with pre-clinical HCM. The purpose of this review is to describe each of these clinical profiles with its prognostic implications.

Surgical Septal Myectomy for Hypertrophic cardiomyopathy. The Iranian Experience

INTRODUCTION

Hypertrophic obstructive cardiomyopathy (HOCM) is a hereditary heart muscle disorder characterized by significant myocardial hypertrophy. we assessed perioperative and long-term follow-up data of Iranian HOCM patients who underwent SM in 2 pioneering centers.

METHODS

Clinical data of patients with HOCM septal myectomy are collected. Thirty-day outcome and long-term follow-up data for recurrence of gradient and mortality are reported.

RESULTS

Ninety-six patients in two different centers enrolled in the study. Most patients of 52 patients in center 1 were male (34/52 [65.3%]).and the mean age was of 36.7  ±  19 years. Syncope before admission was reported in 5.7%, the mean left ventricular ejection fraction on admission was 53  ±  8%, the mean left ventricular outflow tract gradient was 66.3  ±  20.4 mm Hg, and the mean preoperativeseptal thickness was 25.4  ±  6.7 mm. A redo SM was performed in 3 patients (5.8%), mitral valve repair in 5 patients (9.6%), and atrioventricular repair in 5 patients (9.6%). A residual systolic anterior motion was detected in 4 patients (7.7%), the mean postoperative septal thickness was 19  ±  6 mm (25.1% septal thickness reduction), and in-hospital mortality was 5.8% (n  =  3). A longer-term follow-up showed death in 3 patients (5.8%) and late recurrent left ventricular outflow tract obstruction in 1 patient.

CONCLUSIONS

Transaortic myectomy is an effective surgery with acceptable early and late mortality rates. Improvements in functional status are seen in almost all patients. Appropriate SM is crucial to a good clinical outcome. Long-term survival is excellent and cardiac sudden death is extremely rare after a good surgical treatment.

Surgery for Hypertrophic Obstructive Cardiomyopathy: Comprehensive LVOT Management beyond Septal Myectomy

Hypertrophic cardiomyopathy (HCM) is a complex, underestimated, multifaceted disease frequently associated with left ventricular outflow tract (LVOT) obstruction. It is clearly demonstrated that this is due not only to septal hypertrophy but also to systolic anterior motion (SAM) of mitral valve leaflets secondary to mitral valve/subvalvular apparatus abnormalities. Surgical treatment involves performing an extended septal myectomy, eventually followed by ancillary procedures to those structures responsible for maintaining LVOT obstruction, if necessary. In this review, we describe the spectrum of possible surgical techniques beyond septal myectomy and their pathophysiologic rationale.

Hypertrophic cardiomyopathy with moderate septal thickness and mitral regurgitation: long-term surgical results

OBJECTIVES

The aim of this study was to assess the long-term outcomes of different surgical strategies in patients with hypertrophic obstructive cardiomyopathy (HOCM) with septal thickness ≤18 mm and systolic anterior motion (SAM)-related moderate-to-severe mitral regurgitation (MR).

METHODS

Seventy-six HOCM patients with septal thickness 17 [16; 18] mm, resting left ventricle outflow tract gradient 60 [41; 85] mmHg and SAM-related MR ≥2+/4+, underwent septal myectomy alone (54%) or mitral valve (MV) surgery ± myectomy (46%).

RESULTS

No hospital death and no ventricular septal defect occurred. Patients undergoing MV surgery ± myectomy had longer cardiopulmonary bypass and X-clamp times (77 [60-106] vs 51 [44-62] min, P < 0.001 and 56 [45-77] vs 32 [28-41] min, P < 0.001) and higher incidence of low output syndrome (11% vs 0%, P = 0.04). Follow-up was 98.6% complete, median 8 years [3-11]. There were no statistically significant differences in overall survival (P = 0.069) with survival rates at 9 years of 96 ± 4% in the myectomy alone group and 81 ± 8% in the MV surgery ± myectomy one. At 9 years, cumulative incidence function of cardiac death was 12 ± 6% in the MV surgery ± myectomy group vs 0% in the myectomy one, P = 0.06. Multivariable analysis identified age and previous septal alcoholization as predictors of cardiac death (hazard ratio (HR) = 1.1, 95% confidence interval (CI) 1.0-1.1, P = 0.004 and HR = 2.9, 95% CI 1.0-8.3, P = 0.042). The 9-year cumulative incidence function of recurrence of MR ≥2+, with death as competing risk, was 3 ± 2.8% in the MV surgery ± myectomy group vs 25 ± 6.9% in the myectomy one, P = 0.005.

CONCLUSIONS

In HOCM patients with moderate septal thickness and SAM-related MR, as the degree of septal hypertrophy decreases, addressing the abnormalities of the MV apparatus may become necessary to provide a durable resolution of left ventricle outflow tract obstruction and SAM-related MR. However, performing myectomy alone, whenever possible, seems to be associated to a better postoperative course and a trend towards lower cardiac mortality at follow-up, despite a higher rate of residual moderate MR.