Contemporary surgical management of hypertrophic cardiomyopathy, the need for more myectomy surgeons and disease-specific centers, and the Tufts initiative

Innovative Pharmacological Approaches to Hypertrophic Cardiomyopathy: The Emerging Role of Aficamten

Hypertrophic cardiomyopathy (HCM) is a genetic cardiac disorder characterized by left ventricular hypertrophy (LVH), which can lead to left ventricular outflow tract (LVOT) obstruction. Traditional treatments often provide limited symptom relief and may not adequately reduce the LVOT gradient. Myosin inhibitors, such as aficamten, offer a new therapeutic approach by modulating myocardial contractility and improving symptoms. This paper evaluated the efficacy and safety of aficamten in patients with symptomatic HCM. We conducted a comprehensive literature review of studies evaluating aficamten for symptomatic HCM, including clinical trials and observational studies up to July 2024. Data on efficacy, safety, and patient outcomes were extracted and analyzed from a total of 10 studies involving 1,067 patients. Aficamten demonstrated substantial efficacy in reducing the LVOT gradient, with dose-dependent reductions ranging from 3.6% to 48.6%. It also improved symptoms, with 82.3% of patients experiencing reduced left ventricular ejection fraction (LVEF) and notable improvements in New York Heart Association (NYHA) functional class. Exercise capacity was enhanced, as indicated by increased peak oxygen uptake. Safety profiles were generally favorable, though some serious adverse events, such as atrial fibrillation and cardiac dysfunction, were reported. Aficamten was well-tolerated overall, with manageable dose-dependent adverse effects. Aficamten represents a promising advance in the management of symptomatic HCM, offering significant reductions in LVOT gradient and improvement in symptoms and exercise capacity. Its safety profile is generally favorable, although ongoing monitoring is necessary to manage potential adverse effects. Future research should focus on long-term outcomes, comparative effectiveness, and real-world evidence.

Short time effects of two radiofrequency ablation methods on hypertrophic obstructive cardiomyopathy

BACKGROUND

Radiofrequency ablation has been applied for the treatment of hypertrophic obstructive cardiomyopathy (HOCM). The two known procedures are percutaneous intramyocardial septal radiofrequency ablation (PIMSRA) and endocardial radiofrequency septal ablation (ERSA).

METHODS

This study presents a retrospective analysis of the PIMSRA and ERSA procedures in patients with drug-refractory HOCM. A total of 28 patients participated in the study, with 12 receiving PIMSRA and 16 receiving ERSA. The objective of our study was to compare the short-term effects of these two radiofrequency ablation procedures.

RESULTS

At the 30-day follow-up, the PIMSRA group demonstrated a greater reduction in left ventricular outflow tract peak gradient at rest compared to the ERSA group (22.25 [16.72] mmHg versus 47.75 [21.94] mmHg) (p < .01). The values for the PIMSRA group decreased from 99.33 (32.00) mmHg to 22.25 (16.72) mmHg (p < .01), while the ERSA group decreased from 97.75 (30.24) mmHg to 47.75 (21.94) mmHg (p < .01). Only the PIMSRA group exhibited a decrease in mitral regurgitation (MR). The area of MR decreased from 10.13 (4.12) mm2 to 3.65 (2.80) mm2 in the PIMSRA group (p < .01). Additionally, the PIMSRA group experienced reductions in left atrial diameter (LAD) and left ventricular ejection fraction (LVEF)%. The values for LAD changed from 43.58 (7.53) mm to 37.08 (6.92) mm (p = .03), and the values for LVEF% decreased from 65.75 (6.12) pg/mL to 60.83 (4.06) pg/mL (p = .03).

CONCLUSION

In terms of the two types of radiofrequency ablation methods used in HOCM, it has been observed that PIMSRA demonstrates a more favorable early treatment effect compared to ERSA.

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.

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.

Impact of Septal Myectomy Volume on Mitral-Valve Replacement Rate in Hypertrophic Cardiomyopathy Patients

Objective: Mitral regurgitation (MR) induced by systolic anterior motion in patients with hypertrophic cardiomyopathy (HCM) can frequently be abolished with a proficient septal myectomy (SM) without the need for mitral-valve replacement (MVR). ACC guidelines stress the importance of volume in improving outcomes after SM, but there is a lack of data measuring the impact of volume on the need for MVR during SM. This study was designed to assess the impact of institutional volume on MVR rates using national outcomes data. Methods: The Nationwide Inpatient Sample was queried from 1998 to 2011 and a total of 6,207 patients had a diagnosis of HCM and a procedure code for SM. Outcomes were compared between patients who underwent SM (group I) and SM and MVR (group II). Furthermore, patients were stratified into 3 groups based on the number of SMs at the performing institution: low experience (1–24 cumulative SMs), medium experience (25–49 SMs), and high experience (>50 SMs). These patients underwent multivariable analysis to determine the impact of institutional volume on MVR rate. Results: The total MVR rate was 26%. Perioperative outcomes were worse, i.e., there were higher rates of mortality, kidney injury, and urinary complications, in group II than in group I. Only 37.6% of patients were operated on at institutions meeting the guideline criteria of >50 cumulative SMs. When compared to patients in the high-experience group, patients in the low- (OR 2.7, 95% CI 2.3–3.2, p < 0.05) and medium-experience (OR 3.0, 95% CI 2.5–3.6, p < 0.05) groups were more likely to undergo MVR. Conclusion: Compared to reports from SM reference centers, national data suggest that MVR rates are quite high at SM. Patients undergoing SM at centers that do not meet the guideline standard have >2.5× the odds of undergoing MVR compared to those operated on at guideline-endorsed centers.

Heart Rate and Heart Rate Variability of Rhesus Macaques (Macaca mulatta) Affected by Left Ventricular Hypertrophy

Hypertrophic cardiomyopathy (HCM) is frequently associated with sudden cardiac death, presumably due to the development of malignant arrhythmias. The risk of sudden cardiac death due to HCM has been reported to be predicted by assessing electrocardiographic (ECG) changes including frequencies and complexities of arrhythmias as well as heart rate variability (HRV) as an assessment of autonomic balance. Sudden cardiac death in association with naturally-occurring left ventricular hypertrophy (LVH) has been reported in a colony of rhesus macaques and is under investigation as a potential non-human primate model of human HCM. In the present study, 10 rhesus macaques with LVH and 10 without the signs of LVH confirmed by an echocardiographic examination were recruited for assessing ECG and HRV parameters. ECG morphology on 10-s, 6-lead ECG analysis, and the frequency and complexity of arrhythmias as well as HRV on 20-h ambulatory ECG Holter analyses were assessed. On the standard 10-s 6-lead ECG analysis, P wave and QRS complex duration as well as the QRS complex amplitude were significantly increased in the LVH-affected rhesus macaques compared to control rhesus macaques. Analysis of 20-h Holter monitoring revealed no statistically significant differences in the frequency or the complexity of arrhythmias between the LVH and the control groups. Several HRV parameters were smaller in the LVH group than the control group throughout the majority of Holter recordings showing periods of reduced variability, however, no statistically significant differences were achieved across groups and/or time points. These findings indicate that ECG analysis and Holter monitoring of rhesus macaques are feasible and that ECG morphological changes in association with LVH could be used as a possible component of an antemortem screening tool. The rhesus macaques of this study did not reveal clear indications of risk for sudden cardiac death. Further studies are necessary to determine the etiology of sudden cardiac death due in LVH affected rhesus macaques and identify if any parameters of arrhythmia assessment or HRV can be used to predict the development of sudden cardiac death.

Interaction of Adverse Disease Related Pathways in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HC) has been characterized as a generally progressive genetic heart disease, creating an ominous perspective for patients and managing cardiologists. We explored the HC disease burden and interaction of adverse clinical pathways to clarify patient expectations over long time periods in the contemporary therapeutic era. We studied 1,000 consecutive HC patients (52 ± 17 years) at Tufts Medical Center, followed 9.3 ± 8 years from diagnosis, employing a novel disease pathway model: 46% experienced a benign course free of adverse pathways, but 42% of patients progressed along 1 major pathway, most commonly refractory heart failure to New York Heart Association class III or IV requiring surgical myectomy (or alcohol ablation) or heart transplant; repetitive or permanent atrial fibrillation; and least commonly arrhythmic sudden death events. Eleven percent experienced 2 of these therapeutic end points at different times in their clinical course, most frequently the combination of advanced heart failure and atrial fibrillation, whereas only 1% incurred all 3 pathways. Freedom of progression from 1 to 2 disease pathways, or from 2 to 3 was 80% and 93% at 5 years, respectively. Annual HC-related mortality did not differ according to the number of pathways: 1 (0.8%), 2 (0.8%), or 3 (2.4%) (p = 0.56), and 93% of patients were in New York Heart Association classes I or II at follow-up. In conclusion, it is uncommon for HC patients to experience multiple adverse (but treatable) disease pathways, underscoring the principle that HC is not a uniformly progressive disease. These observations provide a measure of clarity and/or reassurance to patients regarding the true long-term disease burden of HC.

Results of surgical septal myectomy for obstructive hypertrophic cardiomyopathy: the Tufts experience

BACKGROUND

For over 50 years, surgical septal myectomy has been the preferred treatment for drug-refractory heart failure symptoms in patients with obstructive hypertrophic cardiomyopathy (HCM). Over this time in the United States, the majority of myectomy operations have been performed in a small number of select referral centers.

METHODS

We have taken the opportunity to report results from the relatively new Tufts HCM Center and surgical program, incorporated 13 years ago, during which 507 myectomies (52±14 years of age; 56% male) were performed by one cardiothoracic surgeon, Dr. Hassan Rastegar.

RESULTS

Resting left ventricular (LV) outflow gradients were reduced from 56±42 mmHg preoperatively to 1.2±6.8 mmHg on most recent echocardiogram 2.0±2.5 years after surgery, and 94% of patients showed clinical improvement to NYHA functional class I or II. The first 200 myectomies were performed without mortality or major complications. Among all patients, 30-day mortality rate was 0.8%. Over follow-up of 3.2±2.8 years, 11 patients died (four due to HCM causes) with long-term survival after myectomy of 94% at 5 years (95% CI: 89-96%) and 91% at 10 years (95% CI: 84-95%), which did not differ from the age- and gender-matched general U.S. population (log-rank P=0.9).

CONCLUSIONS

This experience demonstrates that, with the appropriate support, new HCM surgical programs can provide patients successful relief of outflow obstruction, extended longevity and restored of quality of life.

Septal Ablation for Hypertrophic Obstructive Cardiomyopathy: Transcoronary and Endocardial Approach

Septal reduction therapy is the gold standard treatment method for symptomatic, hypertrophic obstructive cardiomyopathy. Although surgical myectomy is a well-established and effective technique with decades of experience in its application, use of transcoronary alcohol septal ablation has increased precipitously owing to the less-invasive nature of the procedure. Moreover, endocardial septal ablation therapy is a relatively newly defined modality, and outcomes of the procedure are not clearly elucidated yet. In this review, we aimed to present nonsurgical septal reduction approaches in patients with hypertrophic obstructive cardiomyopathy.

The mechanisms, diagnosis and management of mitral regurgitation in mitral valve prolapse and hypertrophic cardiomyopathy

Valvular disease is a frequent cardiac pathology leading to heart failure and, ultimately, death. Mitral regurgitation, defined as the inability of the two mitral leaflets to coapt, is a common valvular disease and a self sustained pathology. A better understanding of the mitral valve histological layers provides a better understanding of the leaflet and chordae changes in mitral valve prolapse. Mitral valve prolapse may occur in myxomatous degenerative abnormalities, connective tissue disorders or in sporadic isolated cases. It is the most common mitral abnormality of non-ischemic cause leading to severe surgery-requiring mitral regurgitation. In addition to standard echocardiographic investigations, newly implemented three-dimensional techniques are being used and they permit a better visualisation, from the so-called ‘surgical view’, and an improved evaluation of the mitral valve. Hypertrophic cardiomyopathy is the most frequent inherited myocardial disease caused by mutations in various genes encoding proteins of the cardiac sarcomere, leading to a marked left ventricular hypertrophy unexplained by other comorbidities. The pathological echocardiographic hallmarks of hypertrophic cardiomyopathy are left ventricular hypertrophy, left ventricular outflow tract obstruction and systolic anterior motion of the mitral valve. The systolic anterior motion of the mitral valve contributes to the development of mitral regurgitation and further narrows the left ventricular outflow tract, leading to more severe symptomatology. Cardiac magnetic resonance imaging accurately measures the left ventricular mass, the degree of diastolic function and it may also be used to distinguish phenotypic variants. The clinical outcome of patients with these pathologies is mostly determined by the selected option of treatment. The purpose of surgical correction regarding mitral valve involvement is to restore valvular competence. Surgery has proven to be the only useful treatment in preventing heart failure, improving symptomatology and reducing mortality. Our approach wishes to enhance the understanding of the mitral valve’s involvement in hypertrophic cardiomyopathy and mitral valve prolapse from genetic, haemodynamic and clinical perspectives, as well as to present novelties in the grand field of treatment.

Outcomes of an extended Morrow procedure without a concomitant mitral valve procedure for hypertrophic obstructive cardiomyopathy

The indications for a concomitant mitral valve (MV) procedure remain controversial for patients with hypertrophic obstructive cardiomyopathy (HOCM). According to previous studies, a concomitant MV surgery was required in 11–20% of inpatient operations. Thus, we aimed to study the outcomes of an extended Morrow procedure without a concomitant MV procedure for HOCM patients who had no intrinsic abnormalities of the MV apparatus. We retrospectively reviewed 232 consecutive HOCM patients who underwent extended Morrow procedures from January 2010 to October 2014. Only 10 (4.31%) patients with intrinsic MV diseases underwent concomitant MV procedures. Of the 232 patients, 230 had no to mild mitral regurgitation (MR) postoperatively. We separated the 232 patients into two groups according to preoperative MR degree. One group is mild MR, and the other is moderate or severe MR. The three-month, one-year, and three-year composite end-point event-free survival rates had no difference between two groups (p = 0.820). When we separated the patients to postoperative no or trace MR group and mild MR group, there was also no difference on survival rates (p = 0.830). In conclusion, concomitant mitral valve procedures are not necessary for HOCM patients with MR caused by systolic anterior motion, even moderate to severe extent.

Surgical Ventricular Septal Myectomy in the Developing World

Surgical septal myectomy is the preferred treatment strategy in hypertrophic cardiomyopathy (HC) to reverse progressive heart failure symptoms due to left ventricular outflow obstruction. However, open-heart surgery and the ventricular septal myectomy option in particular have limited accessibility in many parts of the world, including developing countries such as India, where skilled surgeons familiar with the complex left ventricular outflow tract anatomy of obstructive HC are rare. Indeed, septal myectomy, which is currently performed in only a limited number of countries, can become available in other venues if experienced surgeons dedicate their skills to this highly specialized but rewarding operation. Relevant to this issue, we describe a recent myectomy initiative in India (New Delhi) that demonstrates the possibility of generating a surgical myectomy program outside of an elite academic center environment, otherwise regarded as unfavorable for such an initiative. Demonstration that safe and effective septal myectomy is possible under such difficult circumstances bodes well for the expansion of this operation to many countries in the best interests of the hypertrophic cardiomyopathy patient population.

Hypertrophic Cardiomyopathy in Adulthood Associated With Low Cardiovascular Mortality With Contemporary Management Strategies

BACKGROUND

Hypertrophic cardiomyopathy (HCM) has been prominently associated with adverse disease complications, including sudden death or heart failure death and a generally adverse prognosis, with annual mortality rates of up to 6%.

OBJECTIVES

This study determined whether recent advances in management strategy, including implantable cardioverter-defibrillators (ICDs), heart transplantation, or other therapeutic measures have significantly improved survival and the clinical course of adult HCM patients.

METHODS

We addressed long-term outcomes in 1,000 consecutive adult HCM patients presenting at 30 to 59 years of age (mean 45±8 years) over 7.2±5.2 years of follow-up.

RESULTS

Of 1,000 patients, 918 (92%) survived to 53±9.2 years of age (range 32 to 80 years) with 91% experiencing no or only mild symptoms at last evaluation. HCM-related death occurred in 40 patients (4% [0.53%/year]) at 50±10 years from the following events: progressive heart failure (n=17); arrhythmic sudden death (SD) (n=17); and embolic stroke (n=2). In contrast, 56 other high-risk patients (5.6%) survived life-threatening events, most commonly with ICD interventions for ventricular tachyarrhythmias (n=33) or heart transplantation for advanced heart failure (n=18 [0.79%/year]). SD occurred in patients who declined ICD recommendations, had evaluations before application of prophylactic ICDs to HCM, or were without conventional risk factors. The 5- and 10-year survival rates (confined to HCM deaths) were 98% and 94%, respectively, not different from the expected all-cause mortality in the general U.S. population (p=0.25). Multivariate independent predictors of adverse outcome were younger age at diagnosis, female sex, and increased left atrial dimension.

CONCLUSIONS

In a large longitudinally assessed adult HCM cohort, we have demonstrated that contemporary management strategies and treatment interventions, including ICDs for SD prevention, have significantly altered the clinical course, now resulting in a low disease-related mortality rate of 0.5%/year and an opportunity for extended longevity.

Importance and feasibility of creating hypertrophic cardiomyopathy centers in developing countries: the experience in India

Hypertrophic cardiomyopathy (HC) is a relatively common genetic heart disease responsible for mortality and morbidity at all ages. Using contemporary treatment advances, such as implantable defibrillators, surgical myectomy, heart transplant, and modern defibrillation for out-of-hospital cardiac arrest, it is now possible to reduce HC-related mortality considerably to 0.5% per year, less than expected in the general US adult population. However, in much of the developing world, HC has not yet become a priority given the many other cardiac conditions, such as coronary artery disease and systemic hypertension, so prevalent in the most populous countries such as China and India. Management of HC is best achieved in dedicated centers within institutions, such as previously demonstrated in the United States, Canada, some European countries, and Australia. This model has recently been introduced for the first time in India at the Amrita Institute of Medical Sciences and Research in Kochi, Kerala, in which a robust program focused on HC has emerged. This novel initiative, created despite the many obstacles in the Indian health care system, is an important step forward and is reported here detail.

Advanced Heart Failure With Preserved Systolic Function in Nonobstructive Hypertrophic Cardiomyopathy

Background—

In hypertrophic cardiomyopathy (HCM), heart transplant has been predominantly confined to patients with systolic dysfunction. An underappreciated HCM subset comprises patients with preserved left ventricular (LV) systolic function who may also require consideration for transplantation. Therefore, we sought to define the clinical profile and occurrence of advanced heart failure among patients with nonobstructive HCM and preserved systolic function.

Methods and Results—

Databases from 2 referral centers comprising 2100 HCM patients were interrogated. Forty-six nonobstructive HCM patients (2.2%) either received or were listed for heart transplant, including 20 with normal systolic function (ejection fraction ≥50%). At transplant listing, these 20 patients were 42±13 years old, each in New York Heart Association functional class III/IV with ejection fraction of 62±7%. LV was hypertrophied with maximum wall thickness of 22±4 mm and nondilated (end-diastolic dimension, 39±7 mm). Cardiovascular magnetic resonance in 10 (of 15) patients showed no or minimal fibrosis (≤5% LV mass). Elevated LV end-diastolic or pulmonary capillary wedge pressure, consistent with diastolic dysfunction, was present in 15 patients (75%). LV filling was impaired by echocardiographic measures in all patients, including a restrictive inflow pattern in 8 (40%). In 2 patients, traditional criteria for transplant were absent, including peak V O 2 >14 mL/kg/min. Heart transplantation was performed in 12 patients with each alive and without cardiovascular symptoms, 2.3±1.7 years later.

Conclusions—

A previously under-recognized segment of the broad HCM clinical spectrum consists of nonobstructive patients with advanced heart failure, in the presence of preserved systolic function, for whom heart transplant is the sole definitive therapeutic option.

Hypertrophic cardiomyopathy: present and future, with translation into contemporary cardiovascular medicine

Hypertrophic cardiomyopathy (HCM) is a common inherited heart disease with diverse phenotypic and genetic expression, clinical presentation, and natural history. HCM has been recognized for 55 years, but recently substantial advances in diagnosis and treatment options have evolved, as well as increased recognition of the disease in clinical practice. Nevertheless, most genetically and clinically affected individuals probably remain undiagnosed, largely free from disease-related complications, although HCM may progress along 1 or more of its major disease pathways (i.e., arrhythmic sudden death risk; progressive heart failure [HF] due to dynamic left ventricular [LV] outflow obstruction or due to systolic dysfunction in the absence of obstruction; or atrial fibrillation with risk of stroke). Effective treatments are available for each adverse HCM complication, including implantable cardioverter-defibrillators (ICDs) for sudden death prevention, heart transplantation for end-stage failure, surgical myectomy (or selectively, alcohol septal ablation) to alleviate HF symptoms by abolishing outflow obstruction, and catheter-based procedures to control atrial fibrillation. These and other strategies have now resulted in a low disease-related mortality rate of <1%/year. Therefore, HCM has emerged from an era of misunderstanding, stigma, and pessimism, experiencing vast changes in its clinical profile, and acquiring an effective and diverse management armamentarium. These advances have changed its natural history, with prevention of sudden death and reversal of HF, thereby restoring quality of life with extended (if not normal) longevity for most patients, and transforming HCM into a contemporary treatable cardiovascular disease.