Second Hits in Dilated Cardiomyopathy.

PURPOSE OF REVIEW: Genetic studies have identified an increasing number of culprit disease genes in patients with dilated cardiomyopathy (DCM). While these studies were originally conducted in patients with primary DCM, recent research has identified culprit mutations among patients who develop DCM in response to an environmental exposure. This review will summarize the genetic architecture of DCM secondary to alcohol, anthracyclines, and pregnancy, as well as the potential modifying role of exercise.

RECENT FINDINGS: Mutations in DCM-associated genes are identified in 10-20% of patients categorized as having a secondary cardiomyopathy, a similar frequency to patients with primary DCM. The most commonly mutated gene is TTN, which encodes the sarcomere protein titin. Clinical outcomes differ among patients with or without an identifiable mutation. Genetic contributors should be sought in patients with presumed secondary cardiomyopathy. Future studies are necessary to determine the prospective management of previously unaffected patients known to have a DCM-associated mutation at the time of pregnancy or exposure to cardiotoxins.