Risk of Cardiomyopathy in Younger Persons With a Family History of Death from Cardiomyopathy: A Nationwide Family Study in a Cohort of 3.9 Million Persons.

Abstract

Recommendations for presymptomatic screening of relatives of cardiomyopathy patients are based on findings from tertiary centers. Cardiomyopathy inheritance patterns are fairly well understood, but how cardiomyopathy in younger persons (<50 years) aggregates in families at the population level is unclear. In a nationwide cohort, we examined the risk of cardiomyopathy by family history of premature death (<60 years) from cardiomyopathy. By linking Danish national register data, we constructed a cohort of 3.9 million persons born from 1950 to 2008. We ascertained family history of premature (<60 years) death from cardiomyopathy or other conditions, and cohort members were followed from 1977 to 2008 for cardiomyopathy diagnosed at <50 years. We identified 3890 cardiomyopathies in 89 million person-years of follow-up. Using Poisson regression, we estimated incidence rate ratios for cardiomyopathy by family history of premature death. Premature cardiomyopathy deaths in first- and second-degree relatives were associated with 29- and 6-fold increases in the rate of cardiomyopathy, respectively. If the first-degree relative died aged <35 years, the rate of cardiomyopathy increased 100-fold; given ≥2 premature deaths in first-degree relatives, the rate increased more than 400-fold. In contrast, a family history of premature death from other cardiac or noncardiac conditions increased the rate of cardiomyopathy 3-fold at most. A family history of premature cardiomyopathy death was associated with an increase in risk of cardiomyopathy ranging from 6- to 400-fold, depending on age, kinship, gender and number of affected family members. Our general population-based results support recommendations for presymptomatic screening of relatives of cardiomyopathy patients.