2020 AHA/ACC Guideline for Diagnosis and Treatment of Hypertrophic Cardiomyopathy
The American Heart Association and the American College of Cardiology have updated their guideline on managing hypertrophic cardiomyopathy (HCM).
HCM is a common genetic heart disease reported in populations globally. Inherited in an autosomal dominant pattern, the distribution of HCM is equal by sex, although women are diagnosed less commonly than men.
- Shared decision making is recommended for all aspects of HCM care including genetic testing, activity, lifestyle, and therapy choices.
- Referralll to an HCM center of excellence should be considered to address complex management decisions.
- Initial diagnostic evaluation for all HCM patients should include a comprehensive physical exam with a three-generation family history. Clinical features associated with HCM phenocopies should be assessed.
- An initial electrocardiogram (ECG) and 24- to 48-hour ambulatory ECG monitoring is recommended followed by surveillance ECG every 1-2 years. For palpitations or lightheadedness, extended monitoring is recommended, which should only be considered diagnostic if symptoms occurred while monitoring.
- For all patients with suspected HCM, a transthoracic echocardiogram (TTE) is recommended. If resting left ventricular outflow tract (LVOT) gradient is <50 mm Hg, provocative testing should be performed. For symptomatic patients without provoked gradients, an exercise echocardiogram should be performed. For clinically stable HCM patients, surveillance echocardiograms should be considered every 1-2 years to assess for changes in extent of hypertrophy, obstruction, and cardiac function.
- Cardiac magnetic resonance imaging should be obtained in HCM patients when echocardiography is inconclusive, if there is a suspicion for an alternative diagnosis (like infiltrative/storage diseases), for sudden cardiac death risk stratification, and may be needed for selection and planning of septal reduction therapy.
- For HCM patients with symptoms of myocardial ischemia, computed tomography (CT) or invasive coronary angiography should be considered. Prior to surgical myectomy, invasive or CT angiography should be obtained. For patients who are candidates for septal reduction therapy but there is uncertainty regarding presence of LVOT obstruction on noninvasive studies, invasive hemodynamic assessment is recommended.
- Genetic testing should be offered to HCM patients to elucidate the genetic basis and to allow for family screening. Pre- and post-testing genetic counseling is recommended for individuals undergoing genetic testing. For HCM patients with genetic variants of uncertain significance, serial re-evaluation of test results is recommended to assess for variant reclassification, as this may trigger testing for family members. Preconception and prenatal reproductive and genetic counseling should also be offered.
- In first-degree relatives of patients with HCM, clinical screening should include ECG and TTE during the initial evaluation followed by periodic follow-up according to their age (1-2 years in adolescents, 3-5 years in adults) or if clinical status changes. If the proband has a pathogenic or likely pathogenic variant on genetic testing, cascade genetic testing should be offered. For relatives who test negative on cascade genetic test, additional clinical screening is not recommended.
- For HCM patients with cardiac arrest or sustained ventricular tachycardia (VT), single-chamber transvenous or subcutaneous implantable cardioverter-defibrillator (ICD) implantation is recommended as a Class I recommendation. As a Class IIa recommendation, it is reasonable to offer an ICD for patients with massive LV hypertrophy ≥30 mm, history of suspected cardiac syncope, LV apical aneurysm, systolic dysfunction with ejection fraction (EF) <50%, or family history of sudden cardiac death due to HCM. For patients without these risk factors, ICDs should not be implanted, especially for the sole purpose of participation in competitive athletics.
- For symptomatic HCM patients with LVOT obstruction, nonvasodilating beta-blockers (BBs) are recommended. If BBs are ineffective or not tolerated, verapamil or diltiazem are recommended. Verapamil and diltiazem are contraindicated in case of hypotension, severe dyspnea at rest, children <6 weeks old, and for resting gradients over 100 mm Hg. For symptoms refractory to all these agents, disopyramide may be added or septal reduction therapy may be offered at high-volume centers. If surgical septal reduction is contraindicated, alcohol septal ablation can be considered at experienced centers.
- For symptomatic patients with nonobstructive HCM and preserved LVEF, BBs, verapamil, or diltiazem are recommended.
- For patients with HCM and clinical atrial fibrillation, anticoagulation is recommended, irrespective of CHA2DS2-VASc score, with direct-acting oral anticoagulants as first line followed by warfarin. For HCM patients with subclinical atrial fibrillation, anticoagulation is recommended if atrial fibrillation lasts for over 24 hours.
- For HCM patients with VT or recurrent ICD shocks despite BB use, antiarrhythmic therapy with amiodarone, mexiletine, sotalol, or dofetilide may be considered. If VT remains refractory to antiarrhythmics, heart transplant evaluation should be considered.
- For HCM patients who develop systolic dysfunction with EF <50%, coronary artery disease should be ruled out and guideline-directed therapy for heart failure with reduced EF should be initiated. For patients with New York Heart Association class III-IV symptoms, a cardiopulmonary stress test should be considered to quantify functional limitation and help with decision making regarding advanced heart failure therapies.
- For HCM patients participating in athletics, comprehensive evaluation and shared decision making regarding risk of participating in sports is recommended. For most HCM patients, mild to moderate, recreational, noncompetitive exercise for the purpose of leisure is beneficial.
- For pregnant HCM patients, BBs should be continued with monitoring of fetal growth and care should be coordinated between cardiology and obstetrics. If anticoagulation is indicated for atrial fibrillation or other reasons, low molecular weight heparin or warfarin (if maximum dose <5 mg daily) are recommended.
- While the guideline writers recognize that patients with HCM can be evaluated and treated by a cardiovascular care team, recommendations are made for patients with severe HCM, or those facing complex decisions, to be referred to multidisciplinary HCM centers to receive optimal care.
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