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.

A Narrative Review of Emerging Therapies for Hypertrophic Obstructive Cardiomyopathy

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

Long-term outcomes and risk factors for mortality of patients with hypertrophic obstructive cardiomyopathy undergoing septal myectomy

Background

We aimed to evaluate the long-term surgical outcomes of patients with hypertrophic obstructive cardiomyopathy and explore the risk factors for mortality, especially those related to atrial fibrillation.

Methods

We retrospectively reviewed 150 consecutive patients with hypertrophic obstructive cardiomyopathy who underwent surgical treatment between March 2003 and December 2020.

Results

Fifty (33.3%, age 53.7±16.1 years) patients underwent isolated septal myectomy (SM), 79 (52.7%, age 52.3±12.6 years) underwent SM with mitral valve intervention (SM + MVI), and 21 (14.0%, age 57.1±13.5 years) underwent SM with mitral valve replacement (SM + MVR). Overall peak left ventricular outflow tract pressure gradient at rest was significantly decreased from 91.9±43.2 to 13.3±13.0 mmHg (P<0.0001). Survival rates were 96.7%, 89.1%, and 81.5% at 30 days, 5 years, and 10 years, respectively. Patients in the SM + MVI group survived longer than those in SM + MVR or isolated SM groups (94.1% vs. 75.4% vs. 88.0%, respectively, at 5 years, P=0.05). Patients with preoperative atrial fibrillation had a worse 5-year survival rate than those without atrial fibrillation (73.4% vs. 92.8%, respectively, P<0.001). Preoperative atrial fibrillation was an independent risk factor for late mortality in multivariable analysis. Notably, those whose atrial fibrillation was successfully eradicated by surgical ablation had a better 5-year survival rate than other patients (87.7% vs. 28.6%, respectively, P<0.001).

Conclusions

Surgical outcomes in hypertrophic obstructive cardiomyopathy are favorable in the long-term, except in patients with preoperative atrial fibrillation. Therefore, intraoperative ablation for preoperative atrial fibrillation in hypertrophic obstructive cardiomyopathy should be actively considered to improve patient outcomes.

Targeting Alcohol Septal Ablation in Patients with Obstructive Hypertrophic Cardiomyopathy Candidates for Surgical Myectomy: Added Value of Three-Dimensional Intracoronary Myocardial Contrast Echocardiography

Background: Myocardial contrast two-dimensional echocardiography (MC-2DE) is widely used to address alcohol septal ablation (ASA) in obstructive hypertrophic cardiomyopathy (HCM). Owing to its limited cut-planes, MC-2DE may inaccurately identify the contrast misplacement associated with an unsuccessful or complicated ASA outcome. Objective: The aim of this study was to assess the added value of myocardial contrast three-dimensional echocardiography (MC-3DE) compared with MC-2DE to identify the appropriate matching between the target septal zone (TSZ) and coronary artery branch for safe and long-term effective ASA in HCM patients. Methods: A consecutive series of 52 symptomatic obstructive HCM patients referred for isolated surgical myectomy (SM) was analyzed with MC-2DE and MC-3DE following injection of echocontrast into one or more septal branches. MC-2DE and MC-3DE patterns were categorized according to complete (Type 1) or incomplete (Type 2) TSZ covering, high-risk (Type 3) exceeding TSZ, or life-threatening outside TSZ distribution (Type 4). Results: MC-2DE per patient analysis showed a Type 1 pattern in 32 patients and Types 2–4 in the remaining 20 patients; subsequent MC-3DE analysis provided a re-phenotyping of MC-2DE findings in 22 of the 52 patients (42%), showing a high-risk Type 2 pattern in 17 of the 32 patients with Type 1, and a new life-threatening Type 4 in three patients with Type 2, respectively. All patients with MC-3DE Type 1 pattern underwent safe and effective ASA with a long-term uneventful follow-up, while the remaining patients underwent SM. Conclusions: Refining high risk or life-threatening contrast misplacement, MC-3DE is more accurate than conventional MC-2DE to target safe and long-term effective septal reduction with ASA in obstructive HCM patients referred for isolated SM.

2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This executive summary of the hypertrophic cardiomyopathy clinical practice guideline provides recommendations and algorithms for clinicians to diagnose and manage hypertrophic cardiomyopathy in adult and pediatric patients as well as supporting documentation to encourage their use.

METHODS

A comprehensive literature search was conducted from January 1, 2010, to April 30, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases.

STRUCTURE

Many recommendations from the earlier hypertrophic cardiomyopathy guidelines have been updated with new evidence or a better understanding of earlier evidence. This summary operationalizes the recommendations from the full guideline and presents a combination of diagnostic work-up, genetic and family screening, risk stratification approaches, lifestyle modifications, surgical and catheter interventions, and medications that constitute components of guideline directed medical therapy. For both guideline-directed medical therapy and other recommended drug treatment regimens, the reader is advised to follow dosing, contraindications and drug-drug interactions based on product insert materials.

2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

Aim This executive summary of the hypertrophic cardiomyopathy clinical practice guideline provides recommendations and algorithms for clinicians to diagnose and manage hypertrophic cardiomyopathy in adult and pediatric patients as well as supporting documentation to encourage their use. Methods A comprehensive literature search was conducted from January 1, 2010, to April 30, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Structure Many recommendations from the earlier hypertrophic cardiomyopathy guidelines have been updated with new evidence or a better understanding of earlier evidence. This summary operationalizes the recommendations from the full guideline and presents a combination of diagnostic work-up, genetic and family screening, risk stratification approaches, lifestyle modifications, surgical and catheter interventions, and medications that constitute components of guideline directed medical therapy. For both guideline-directed medical therapy and other recommended drug treatment regimens, the reader is advised to follow dosing, contraindications and drug-drug interactions based on product insert materials.

Impact of Sex on Clinical Course and Survival in the Contemporary Treatment Era for Hypertrophic Cardiomyopathy

Background

The relation of sex to clinical presentation and course in hypertrophic cardiomyopathy (HCM) remains incompletely resolved. We assessed differences in clinical outcomes between men and women within our large HCM cohort.

Methods and Results

Of 2123 consecutive patients, a minority (38%) were women who were diagnosed with HCM at older ages or referred for subspecialty evaluation later than men (50±19 versus 44±16 and 55±18 versus 49±16; P<0.001). Women more commonly developed advanced New York Heart Association class III/IV symptoms (53% versus 35% in men; P<0.001), predominantly secondary to outflow obstruction. While end‐stage heart failure with systolic dysfunction (ejection fraction <50%) was similar in men (5% versus 4% in women; P=0.33), women were 3‐fold more likely to develop heart failure with preserved systolic function (7.5% versus 2.6%; P=0.002). Sudden death events terminated by defibrillator therapy were similar in women (0.9%/year) versus men (1.0%/year; hazard ratio, 0.92; 95% CI, 0.6–1.5; P=0.73). HCM mortality was uncommon, with identical rates in both sexes (0.3%/year; hazard ratio, 1.5; 95% CI, 0.7–3.4;, P=0.25). Age‐adjusted all‐cause mortality also did not differ between women and men (1.7% versus 1.3%/year; hazard ratio, 1.32; 95% CI, 0.92–1.91; P=0.13).

Conclusions

Survival was not less favorable in women with HCM. Contemporary treatments including surgical myectomy to reverse heart failure and defibrillators to prevent sudden death, were effective in both sexes contributing to low mortality. However, despite more frequent outflow obstruction, women with HCM are underrecognized and referred to centers later than men, often with more advanced heart failure. Greater awareness of HCM in women should lead to earlier diagnosis and treatment, with implications for improved quality of life.

Guideline-Based Referral for Septal Reduction Therapy in Obstructive Hypertrophic Cardiomyopathy Is Associated With Excellent Clinical Outcomes

BACKGROUND

The outcome of medically refractory patients with obstructive hypertrophic cardiomyopathy treated according to the American College of Cardiology/American Heart Association consensus guideline recommendations is not known. The objectives of this study were to define the short- and long-term outcomes of medically refractory obstructive hypertrophic cardiomyopathy patients undergoing alcohol septal ablation (ASA) and surgical septal myectomy (SM) with patient management in accordance with these consensus guidelines, as well as to quantify procedural risk and burden of comorbid conditions at the time of treatment.

METHODS AND RESULTS

Patients with obstructive hypertrophic cardiomyopathy referred for either ASA or SM from 2004 to 2015 were followed for the primary end point of short- and long-term mortality and compared with respective age- and sex-matched US populations. Of 477 consecutive severely symptomatic patients, 99 underwent ASA and 378 SM. Compared with SM, ASA patients were older ( P<0.001), had a higher burden of comorbid conditions ( P<0.01), and significantly higher predicted surgical mortality ( P<0.005). Procedure-related mortality was 0.3% and similarly low in both groups (0% in ASA and 0.8% in SM). Over 4.0±2.9 years of follow-up, 95% of patients had substantial improvement in heart failure symptoms to New York Heart Association class I/II (96% in SM and 90% in ASA). Long-term mortality was similar between the 2 groups with no difference compared with age- and sex-matched US populations.

CONCLUSIONS

Guideline-based referral for ASA and SM leads to excellent outcomes with low procedural mortality, excellent long-term survival, and improvement in symptoms. These outcomes occur in ASA patients despite being an older cohort with significantly more comorbidities.

Alcohol septal ablation vs myectomy for symptomatic hypertrophic obstructive cardiomyopathy: Systematic review and meta-analysis

BACKGROUND

Surgical myectomy (SM) and Alcohol septal ablation (ASA) are effective therapies for patients with hypertrophic cardiomyopathy who remain symptomatic despite medical therapy. A plethora of data has recently emerged on the long-term outcomes of these procedures. We hence sought to perform an updated meta-analysis comparing both procedures.

METHODS

Studies reporting long-term (>3-years) outcomes of SM and/or ASA were included. The primary endpoint was all-cause mortality. Secondary endpoints included cardiovascular mortality, sudden cardiac death (SCD), reintervention, and complications including death, pacemaker implantation, and stroke.

RESULTS

Twenty-two ASA cohorts (n = 4213; follow-up = 6.6-years) and 23 SM cohorts (n = 4240; follow-up = 6.8-years) were included. Septal myectomy was associated with higher periprocedural mortality and stroke (2% vs 1.2%, P = 0.009 and 1.5% vs 0.8% P = 0.013, respectively), but ASA was associated with more need of pacemaker (10% vs 5%, P < 0.001). During long-term follow-up, all-cause mortality, cardiovascular mortality, and sudden cardiac death rates were 1.5%, 0.4%, and 0.3% per person-year in the ASA group and 1.1%, 0.5%, and 0.3% per person-year in the SM group (P = 0.21, P = 0.53, P = 0.43), respectively. Repeat septal reduction intervention(s) were more common after ASA (11% vs 1.5%, P < 0.001).

CONCLUSION

Compared with SM, ASA is associated with lower periprocedural mortality and stroke but higher rates of pacemaker implantations and reintervention. However, there was no difference between ASA and SM with regards to long-term all-cause mortality, cardiovascular mortality, or SCD.

Interventional therapies for relief of obstruction in hypertrophic cardiomyopathy: discussion and proposed clinical algorithm

Hypertrophic cardiomyopathy (HCM), a disease formerly thought rare in clinical practice, is now believed to affect as many as 1 in 300 individuals, regardless of race or gender. Rising awareness, coupled with advanced imaging and the development of dedicated HCM centers of excellence, has led to more patients coming to clinical presentation. While some are diagnosed at a young age, others are diagnosed in middle age or well into advanced age. Unfortunately, many such patients have progressed clinically to overt heart failure, or have some combination of advanced symptoms including dyspnea, angina, pre-syncope or syncope, palpitations, and edema. Anatomic subsets, including those with mid-ventricular obstruction or apical disease, with or without apical aneurysm, have also been seen in increasing frequency. Fortunately, both percutaneous and surgical invasive options are available across the spectrum of disease severity and anatomy, with outcomes continuing to improve as the techniques and experience evolve. Advances in both approaches allow targeted and individualized treatment of the majority of these patients. This review will focus on interventional approaches to relief of obstruction, and will provide a current clinical algorithm from our center for determining when an interventional approach may be recommended or optimal over a surgical approach, and vice versa.

How to Treat Obstructions in Patients with Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is characterized by the presence of increased thickness of the left ventricular wall that is not solely explained by abnormal loading conditions. Two-thirds of the patients with HCM have an obstruction in the left ventricle after provocation or even while at rest. This obstruction is associated with more symptoms and a worse prognosis. The two main therapeutic approaches for treating a left ventricular obstruction are alcohol septal ablation and surgical myectomy. Both these techniques are discussed in this article. Currently, the final decision concerning the optimal invasive therapy for patients with obstructive HCM must be individualized to each patient depending on his/her wishes and expectations, way of life, age, heart morphology, and hemodynamics, as well as the experience of the treating center.

Management of hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is clinically defined as unexplained myocardial hypertrophy, and it is an autosomal dominant disease of the cardiac sarcomere. It is present in 1 in 500 in the general adult population, making it the most common genetic cardiovascular disease. The pathophysiology of HCM is complex, leading to significant variability in clinical presentation. This, combined with the lack of randomized trials, makes the management of these patients difficult.

FINDINGS

The majority of patients with HCM are asymptomatic without a substantial reduction in survival. However, a considerable portion of patients will experience significant symptoms and HCM-related death, and effective therapies are available for these patients. Patients may have symptoms of heart failure from outflow tract obstruction and/or restrictive physiology. Medical therapy targeted at the underlying pathophysiology should be used, and surgical myectomy or alcohol septal ablation is available for those with refractory symptoms. While the overall risk of sudden cardiac death (SCD) is low in HCM patients, some are at elevated risk for and experience SCD, a devastating outcome in young patients. Risk stratification for SCD and treatment with implantable cardioverter-defibrillators is paramount. Many HCM patients will also develop atrial fibrillation, and this is often poorly tolerated. A rhythm control strategy with antiarrhythmic drugs or catheter ablation is often necessary, and anticoagulation should be administered to reduce the risk of thromboembolism. Finally, family members of patients with HCM should be regularly screened with electrocardiography and echocardiography.

CONCLUSIONS

HCM is a complex disease with heterogeneous phenotypes and clinical manifestations. The management of HCM focuses on reducing symptoms of heart failure, preventing SCD, treating atrial fibrillation, and screening family members. Treatment should be tailored to the unique characteristics of each individual patient.