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Risk stratification in hypertrophic cardiomyopathy
G Vassalli1, C Seiler, O M Hess
1Department of Internal Medicine, Cardiology, University Hospital, Zürich, Switzerland.
Insights
Hypertrophic cardiomyopathy, a genetic heart disorder, involves left ventricular hypertrophy. Mutations in the beta-cardiac myosin heavy chain gene are common, impacting prognosis and disease presentation.
Area of Science:
- Cardiology
- Genetics
- Molecular Biology
Background:
- Hypertrophic cardiomyopathy (HCM) is an inherited myocardial disorder.
- It is characterized by left ventricular hypertrophy, myocyte disarray, and autosomal inheritance.
- Genetic mutations, particularly in the beta-cardiac myosin heavy chain gene, are implicated in HCM development.
Purpose of the Study:
- To review the genetic basis of hypertrophic cardiomyopathy.
- To discuss genotype-phenotype correlations and their clinical implications.
- To highlight prognostic factors and disease outcomes.
Main Methods:
- Review of genetic linkage analyses and mutation databases.
- Analysis of genotype-phenotype correlations in HCM patients.
- Evaluation of clinical manifestations, progression, and mortality data.
Main Results:
- Mutations in the beta-cardiac myosin heavy chain gene account for 30-50% of HCM cases.
- Additional genetic loci on chromosomes 1q3, 11p13-q13, and 15q2 are associated with HCM.
- Despite identified mutations, significant diversity in clinical presentation and prognosis exists, even within families.
- Annual mortality is approximately 3%, linked to heart failure and sudden cardiac death.
- Nonsustained ventricular tachycardia with syncope history indicates a poor prognosis.
Conclusions:
- HCM is a genetically complex disease with variable clinical outcomes.
- Understanding genetic mutations aids in predicting prognosis.
- Further research is needed to identify all causative genes and refine therapeutic strategies.
Abstract:
Hypertrophic cardiomyopathy is a primary myocardial disorder with an autosomal pattern of inheritance, characterized by asymmetric left ventricular hypertrophy with myocyte and myofibrillar disarray. Approximately 30% to 50% of all cases are accounted for by mutations in the beta-cardiac myosin heavy chain gene on chromosome 14q1. Recent linkage analysis led to the association of the disease with additional loci on chromosomes 1q3, 11p13-q13, and 15q2, but the underlying gene defects are as yet unidentified. To date, about 34 mutations of the beta-cardiac myosin heavy chain gene have been described and shown to have important prognostic implications. Definite genotype-phenotype correlations have been described; however, wide diversity in cardiac morphology, pathophysiologic features, and clinical manifestations is still evident, even within the same family. The disease has an annual mortality of approximately 3%, related to both progressive heart failure and sudden cardiac death. Not only diastolic but also progressive systolic dysfunction with cavity dilatation occurs in a minority of patients with severe left ventricular hypertrophy. These patients usually have a poor prognosis, especially when atrial fibrillation ensues. Sudden death often occurs in young, asymptomatic or mildly symptomatic patients. The degree of hypertrophy and the presence of a pressure gradient are of little prognostic significance. Nonsustained ventricular tachycardia is associated with a poor prognosis in the presence of a history of syncope.