Clinical course of hypertrophic cardiomyopathy in a regional United States cohort
B J Maron1, S A Casey, L C Poliac
1Cardiovascular Research Division, Minneapolis Heart Institute Foundation, School of Public Health, University of Minnesota, 55407, USA. gencvres@skypoint.com
Insights
Hypertrophic cardiomyopathy (HCM) in a general population does not significantly increase premature death risk or reduce overall life expectancy. Referral bias from specialized centers may create misconceptions about HCM
Area of Science:
- Cardiology
- Genetics
- Internal Medicine
Background:
- Hypertrophic cardiomyopathy (HCM) traditionally associated with high disability and mortality (up to 6% annually).
- Previous data largely derived from tertiary referral centers, potentially skewing outcomes.
- Need to assess HCM's true clinical course in a representative patient population.
Purpose of the Study:
- To evaluate the clinical course and mortality of hypertrophic cardiomyopathy (HCM) in a regional cohort.
- To determine if HCM significantly impacts overall life expectancy in a non-referred patient population.
- To identify predictors of mortality in patients with HCM.
Main Methods:
- Retrospective cohort study of 277 consecutively managed HCM patients.
- Regional cohort from Minnesota, minimizing referral bias.
- Follow-up for mortality and clinical outcomes, comparing to general population data.
Main Results:
- Annual HCM mortality rate was 1.3% (0.7% for sudden cardiac death).
- Adult-identified HCM patients showed no significant difference in mortality compared to the general population.
- Children identified with HCM had decreased survival (P<.001); advanced symptoms predicted mortality.
Conclusions:
- Regional HCM cohort suggests the disease does not significantly increase premature death risk or reduce overall life expectancy.
- Referral patterns to specialized centers may contribute to misconceptions about HCM's prognosis.
- HCM remains complex, with serious consequences and potential for premature death in a subset of patients.
Context:
Hypertrophic cardiomyopathy (HCM) has been regarded as a disease that causes substantial disability, with annual mortality rates of up to 6%, based largely on reports from tertiary referral centers.
Objective:
To assess the clinical course of HCM in a patient cohort more closely resembling the true disease state.
Design:
Retrospective cohort study.
Setting:
A regional cohort from Minnesota and adjoining regions, free of referral center bias, studied at Minneapolis Heart Institute.
Patients:
Two hundred seventy-seven consecutively studied HCM patients, none referred for specialized HCM care, managed clinically in a standard fashion.
Main Outcome Measures:
Mortality and clinical course of HCM.
Results:
During a mean (SD) follow-up of 8.1 (6.6) years, 45 patients died and 29 of these deaths were directly related to HCM; however, 8 of the 29 HCM deaths were not premature (occurring >75 years of age). Annual HCM mortality rate was 1.3% (0.7% for sudden cardiac death). Patients identified in adulthood (n = 234) showed no statistically significant difference in mortality when compared with expected mortality, as calculated for the general US or Minnesota populations (P=.17). Patients identified as children (n=43) showed decreased survival compared with the general population (P<.001). At most recent clinical evaluation, 192 patients (69%) had no or mild symptoms and 69 (25%) experienced incapacitating symptoms or HCM-related death; 53 (19%) of the patients had achieved estimated life expectancy of 75 years or older. More advanced symptoms at diagnosis-occurrence of atrial fibrillation (often associated with stroke), the presence of basal outflow obstruction of at least 30 mm Hg, and marked left ventricular wall thickness of more than 25 mm-were clinically important independent predictors of HCM mortality.
Conclusions:
In a regionally selected patient population most closely resembling the true disease state, HCM did not significantly increase the risk of premature death or adversely affect overall life expectancy. Prevailing misconceptions of HCM as a generally unfavorable condition may largely be related to the skewed patient referral patterns characteristic of tertiary care centers. Hypertrophic cardiomyopathy is nevertheless a highly complex disease capable of serious clinical consequences and premature death in some patients.
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