Chapter 58: Dilated Cardiomyopathy
A 42-year-old man presents to your clinic to establish care for a newly diagnosed dilated cardiomyopathy (DCM). His previous evaluation is notable for the absence of coronary artery disease. Review of his family history reveals that his father also had DCM and his sister has DCM. Which of the following is not true about familial DCM?
A. DCM is familial in more than 60% of cases
B. This patient has an X-linked cardiomyopathy allele
C. The most common cause of familial DCM is mutations to sarcomeric genes
D. Of the nuclear envelope genes, mutations to LMNA most often result in DCM
E. Most DCM genes also cause other types of cardiomyopathy
The answer is B. (Hurst’s The Heart, 14th Edition, Chap. 58) In more than 60% of cases of DCM, the disease is familial, as proven by clinical family screening demonstrating that more than one member is affected or shows traits that predict the development of the disease (option A).1,2 This patient likely has an autosomal dominant allele. This patient’s father is affected, and because he did not inherit an X chromosome from his father, the disease allele cannot be X-linked (option B). Sarcomere genes (TTN, MYH7, MYBPC3, TNNT2, TNNI3, MYL2, MYL3) are mutated in 25% to 30% of DCM patients (option C).3 Nuclear envelope genes (LMNA, EMD, SYNE1, TMPO) are mutated in about 7% to 10% of cases, with LMNA mutations accounting for the majority of DCM in this subgroup (option D).4 Most DCM genes also cause other types of cardiomyopathy (HCM, restrictive cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy (option E).
A 43-year-old woman is found to have a mutation of LMNA2 associated with DCM. An echocardiogram reveals an ejection fraction of 40%. Which of the following is true of cardiac laminopathies that occur due to mutations of LMNA2?
A. Conduction system disease often presents prior to DCM
B. Progression of the PR interval is associated with cardiac laminopathies due to mutations of LMNA2
C. Patients with cardiac laminopathies due to mutations of LMNA2 are at high risk for ventricular tachycardia and sudden death
D. Prophylactic ICD implantation would be indicated for this patient if she demonstrated nonsustained ventricular tachycardia on ambulatory ECG monitoring
The answer is E. (Hurst’s The Heart, 14th Edition, Chap. 58) The development of conduction system disease usually ...