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How Common Is Silent Heart Disease in the Relatives of Patients with Heart Failure?
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What is the problem and what is known about it so far?
Idiopathic dilated cardiomyopathy (IDC) is a disease that causes diffuse weakening of the heart muscle for no apparent reason. Most people with the disease do not realize that they have it until they develop symptoms of heart failure (such as shortness of breath), but the disease may be developing for a long time before it causes symptoms. Idiopathic dilated cardiomyopathy sometimes occurs in families as an inherited form of the disease. Relatives of people with the inherited form may have heart abnormalities that indicate an early form of IDC even though they have no symptoms. Testing relatives of people with inherited IDC could lead to earlier detection of the disease and earlier treatment.
Why did the researchers do this particular study?
To see how many relatives of patients with IDC have heart abnormalities that may be an early form of the disease and how many of those relatives developed established disease.
Who was studied?
189 patients with IDC and 767 of their apparently healthy relatives.
How was the study done?
The researchers examined each participant. They performed electrocardiography and echocardiography to identify abnormalities that are characteristic of IDC. They then repeated the tests between 1 month and 11 years later to see whether any relative developed established IDC.
What did the researchers find?
About 1 in 3 patients with IDC had at least 1 relative with either established or possible early IDC (1 in 5 patients had abnormalities suggestive of early disease, and 1 in 20 patients had established disease). Only about 1 in 100 relatives who had healthy hearts on initial testing developed abnormalities suggestive of early disease, but about 1 in 10 relatives who had early disease developed established disease. Those with early disease developed established disease 10 times more commonly than healthy participants.
What are the limitations of the study?
Members of families in which disease is more common may be more likely to have disease but may also be more willing to volunteer for studies than members of families in which disease is less common. Willingness to participate may also have been affected by how close participants lived to the clinic. The methods used to detect early changes of IDC are not perfect and may have misidentified some cases.
What are the implications of the study?
Idiopathic dilated cardiomyopathy is relatively common in apparently healthy relatives of patients with the disease. There may be a role for testing those relatives even though they do not have symptoms, because early detection could lead to earlier treatment and better outcomes.
Article and Author Information
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The summary below is from the full report titled “Echocardiographic Evaluation in Asymptomatic Relatives of Patients with Dilated Cardiomyopathy Reveals Preclinical Disease.” It is in the 19 July 2005 issue of Annals of Internal Medicine (volume 143, pages 108-115). The authors are N.G. Mahon, R.T. Murphy, C.A. MacRae, A.L.P. Caforio, P.M. Elliott, and W.J. McKenna.
