Hypertrophic Cardiomyopathy: Present and Future, With Translation Into Contemporary Cardiovascular Medicine
The following are 10 points to remember from a state-of-the-art review of hypertrophic cardiomyopathy (HCM):
1. HCM is regarded as the most common inherited cardiac disease with diverse phenotypic and genetic expression.
2. HCM is inherited in an autosomal dominant pattern. Although 70% of successfully genotyped patients are found to have mutations in the two most commonly involved genes, beta-myosin heavy chain and myosin-binding protein C, there are now more than 1,500 known individual mutations.
3. Such genetic heterogeneity limits the value of genetic testing in HCM, which is primarily used to identify affected family members. Results of genetic testing do not influence treatment strategies in HCM.
4. There is no compelling evidence that genotype positive-phenotype negative individuals are at increased risk of sudden cardiac death and such family members of affected individuals are not excluded from competitive athletics.
5. Screening for HCM is universally recommended for family members of affected individuals. Echocardiographic screening should begin at 12 years of age and follow at 12- to 18-month intervals until 18-20 years of age. As phenotypic conversion may occur in adulthood, screening should continue at every 5-year interval in those between 20 and 50 years of age.
6. Although HCM is often compatible with normal life expectancy, disease progression may occur along one of three pathways: arrhythmic sudden death risk, progressive heart failure, or atrial fibrillation with risk of stroke.
7. While identification of patients for prophylactic implantable cardioverter-defibrillator (ICD) therapy can be complicated, the five following major risk markers can identify the majority of patients who stand to benefit: family history of sudden cardiac death, unexplained syncope, multiple repetitive nonsustained supraventricular tachycardia on Holter monitoring, abnormal exercise blood pressure response, late gadolinium enhancement (LGE) ≥15% of left ventricular mass, and massive left ventricular hypertrophy ≥30 mm. ICD therapy is the only treatment shown to prolong life in HCM.
8. Contrast-enhanced magnetic resonance imaging has a growing role in resolving complex ICD decisions; the presence of extensive LGE supports the decision to proceed with ICD.
9. In HCM patients with outflow tract obstruction and limiting heart failure symptoms, pharmacological therapy with beta-adrenergic antagonists is first-line therapy.
10. Surgical septal myectomy is the preferred treatment for HCM patients with advanced symptoms despite maximal medical management, and with an outflow gradient ≥50 mm Hg at rest and/or with provocation.
Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Magnetic Resonance Imaging
Keywords: Hypertrophy, Left Ventricular, Tachycardia, Supraventricular, Stroke, Cardiomyopathy, Hypertrophic, Life Expectancy, Syncope, Blood Pressure, Genetic Testing, Adrenergic Antagonists, Magnetic Resonance Imaging, Mutation, Tachycardia, Ventricular, Heart Failure, Electrocardiography, Ambulatory, Death, Sudden, Cardiac, Defibrillators, Implantable, Disease Progression, Ventricular Myosins
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