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Natural history of hypertrophic cardiomyopathy. A population-based study, 1976 through 1990
C R Cannan1, G S Reeder, K R Bailey
1Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN 55905, USA.
Insights
Hypertrophic cardiomyopathy is generally a benign condition, but hypertensive hypertrophic cardiomyopathy carries a higher risk of death. This population-based study reveals insights into the natural history of these conditions.
Area of Science:
- Cardiology
- Epidemiology
- Genetics
Background:
- Hypertrophic cardiomyopathy (HCM) exhibits significant heterogeneity in its presentation and progression.
- Existing knowledge of HCM natural history is primarily from hospital-based studies, potentially affected by referral bias.
Purpose of the Study:
- To investigate the natural history of hypertrophic cardiomyopathy in an unselected population.
- To differentiate the outcomes of typical HCM from hypertensive hypertrophic cardiomyopathy.
Main Methods:
- Population-based study utilizing the Rochester Epidemiology Project.
- Retrospective chart review for baseline data and follow-up events.
- Echocardiography for diagnosis; categorization based on hypertension status.
Main Results:
- 37 patients diagnosed with HCM had favorable survival rates (1- and 5-year: 95% and 92%), similar to the general population.
- 24 patients with hypertensive hypertrophic cardiomyopathy had significantly worse survival (1- and 5-year: 75% and 43%).
- Factors associated with decreased survival included atrial fibrillation, myocardial infarction history, and advanced New York Heart Association functional class.
Conclusions:
- Hypertrophic cardiomyopathy is often more benign than suggested by referral center data.
- Hypertensive hypertrophic cardiomyopathy represents a high-risk subset with reduced survival rates.
- Identifying specific clinical factors aids in predicting outcomes for HCM patients.
Background:
Hypertrophic cardiomyopathy is a disease entity characterized by marked heterogeneity in morphology and natural history. Most of our knowledge of the natural history of this disorder derives from the study of hospital-based populations and is influenced by referral bias. Therefore, this population-based study was undertaken to examine the natural history of hypertrophic cardiomyopathy among unselected residents of Olmsted County, Minnesota.
Methods And Results:
Patients with hypertrophic cardiomyopathy, confirmed by echocardiography, were identified by use of the resources of the Rochester Epidemiology Project. Patients with the echocardiographic features of hypertrophic cardiomyopathy but with long-standing hypertension requiring drug therapy were categorized as having hypertensive hypertrophic cardiomyopathy. Baseline clinical details and follow-up events were obtained by retrospective chart review. Thirty-seven patients were diagnosed with hypertrophic cardiomyopathy and 24 with hypertensive hypertrophic cardiomyopathy. Eight additional patients were first diagnosed at autopsy. The mean age of the 37 patients with hypertrophic cardiomyopathy was 59 +/- 20 years (range, 1 week to 92 years); the mean ventricular septal thickness was 17.5 +/- 3 mm. Follow-up was obtained for a median of 7.7 years (range, 45 days to 17.2 years). The 1- and 5-year survival rates were 95% and 92%, respectively; these rates did not differ from those of an age- and sex-matched population (P = NS). The annual risk of cardiac death was 0.7%. The mean age of patients with hypertensive hypertrophic cardiomyopathy was 79 +/- 8 years (range, 62 to 91 years), and the mean ventricular septal thickness was 19 +/- 2.5 mm. Follow-up was obtained for a median of 2.8 years (range, 4 days to 16.7 years). The 1- and 5-year survival rates were 75% and 43%, respectively, which differed sharply from the expected rates of 94% and 70% (P = .0028). The annual risk of cardiac death was 5%. Atrial fibrillation and evidence for myocardial infarction on ECG, use of digoxin and diuretics, and a high New York Heart Association functional class at presentation were all associated with decreased survival by multivariate analysis for both groups combined. A history of myocardial infarction, atrial fibrillation, and mitral annual calcification at presentation were associated with cardiac death.
Conclusions:
Hypertrophic cardiomyopathy is a more benign disease than previously reported from tertiary referral centers. Patients assessed as having hypertensive hypertrophic cardiomyopathy represent a subset at higher risk for cardiac and noncardiac death, with an overall decreased survival rate.