Clinical Utility

Dilated cardiomyopathy (DCM) is a disease of the heart muscle that is diagnosed based on the findings of both left ventricular enlargement and systolic dysfunction, resulting in a reduction in the myocardial force of contraction. This condition is primarily determined by echocardiogram to measure cardiac chamber dimensions, ventricular thickness, and ejection fraction. DCM usually presents with one or more of the following; i) heart failure with symptoms of congestion (edema, orthopnea or paroxysmal dyspnea), ii) reduced cardiac output, resulting in fatigue or dyspnea on exertion, arrhythmias and/or conduction system disease and iii) thromboembolic disease or stroke, mainly from left ventricular mural thrombus. However, individuals with DCM may also be asymptomatic. The prevalence of idiopathic DCM is at least 1/2,700 in the general population.

Left ventricular non-compaction (LVNC) is characterized by abnormal trabeculations in the left ventricle, most frequently at the apex. Prominent trabeculations and deep intertrabecular recesses give the myocardium a sponge-like appearance that can be detected using echocardiogram. LVNC can share the same clinical presentation as DCM, ranging from asymptomatic disease to progressive deterioration of cardiac function, arrhythmias, thromboembolic events, or sudden cardiac death. LVNC is a rare condition, which affects less than 0.3% of the population. While DCM/LVNC can be an isolated finding, it can also occur in association with neuromuscular disorders or mitochondrial myopathy. In addition, DCM/LVNC can be a presenting feature of various genetic syndromes, including Danon disease, Carvajal Syndrome, Barth syndrome, or Emery-Dreifuss muscular dystrophy.

A genetic diagnosis may have implications for treatment, management, recurrence risk, and family member testing.