Excessive Trabeculation of the Left Ventricle: JACC: Cardiovascular Imaging Expert Panel Paper.

Excessive trabeculation, often referred to as "noncompacted" myocardium, has been described at all ages, from the fetus to the adult. Current evidence for myocardial development, however, does not support the formation of compact myocardium from noncompacted myocardium, nor the arrest of this process to result in so-called noncompaction. Excessive trabeculation is frequently observed by imaging studies in healthy individuals, as well as in association with pregnancy, athletic activity, and with cardiac diseases of inherited, acquired, developmental, or congenital origins. Adults with incidentally noted excessive trabeculation frequently require no further follow-up based on trabecular pattern alone. Patients with cardiomyopathy and excessive trabeculation are managed by cardiovascular symptoms rather than the trabecular pattern. To date, the prognostic role of excessive trabeculation in adults has not been shown to be independent of other myocardial disease. In neonates and children with excessive trabeculation and normal or abnormal function, clinical caution seems warranted because of the reported association with genetic and neuromuscular disorders. This report summarizes the evidence concerning the etiology, pathophysiology, and clinical relevance of excessive trabeculation. Gaps in current knowledge of the clinical relevance of excessive trabeculation are indicated, with priorities suggested for future research and improved diagnosis in adults and children. [Display omitted] • Current evidence shows that the extent of trabeculated vs compact myocardium in the adult is determined by differential (allometric) growth of each myocardial layer. Because trabeculated myocardium does not coalesce to form the compact myocardial wall, the term "left ventricular noncompaction" is inaccurate and use should be discouraged. • Excessive trabeculation, as diagnosed using existing criteria, may be present as a normal variant or as a response to preload conditions. • In adults incidentally found to have excessive trabeculation with normal myocardial function and morphology, clinical management is determined by other cardiovascular symptoms or abnormalities, without regard to trabecular pattern. • In adults diagnosed with hypertrophic or dilated cardiomyopathy where excessive trabeculation is also present, the extent of ventricular trabeculation has not been demonstrated to alter management nor prognosis. Following guidelines developed specifically for those conditions is recommended. • In infants and children, caution is warranted because fewer data are available regarding the etiology and prognosis of excessive trabeculation. Clinical evaluation for occult neuromuscular disease or another genetic/metabolic etiology may be appropriate. [ABSTRACT FROM AUTHOR]