Screening Relatives of Early-onset Unexplained Cardiomyopathy Patients
By Daniel Dries, MD, MPH, FACC
Current guidelines recommend screening of family members of young patients (age < 50 years) diagnosed with “idiopathic” or unexplained dilated cardiomyopathy. It is also recommended that a three-generation family history be obtained for all patients with cardiomyopathy to detect familial aggregation suggestive of a “familial cardiomyopathy,” which is most often inherited in an autosomal dominant manner. However, the relationship between early-onset unexplained cardiomyopathy in a younger individual and the risk of cardiomyopathy in that person’s close relatives is based on small studies with limited controls, conducted at tertiary referral centers.
A recent study published in Circulation1 provides some intriguing additional data relevant to this issue, obtained from a large population study. In this study, the investigators examined Danish national register data from 3.9 million persons born between 1950 and 1980, in which there were 3,890 cases of cardiomyopathy in 89 million person-years of follow-up. The records were detailed enough to allow the investigators to examine family history of premature deaths (< 60 years) from cardiomyopathy or other causes and to determine degree of relatedness to the index case of cardiomyopathy. They demonstrated that a family history of premature cardiomyopathy was associated with an increased risk of cardiomyopathy that ranged from 6- to 400-fold, depending on age, kinship, gender and number of affected family members; this is consistent with a dominant Mendelian inheritance pattern. These data support a strategy of screening family members when index cases of cardiomyopathy are identified in persons younger than 50 years old.