Understanding left ventricular hypertrabeculation/noncompaction: pathomorphologic findings and prognostic impact of neuromuscular comorbidities.

INTRODUCTION: When >3 trabeculations associated with interventricular recesses are found, this is termed 'left ventricular hypertrabeculation/noncompaction' (LVHT). Cardiac-imaging methods detect LVHT in all ages, isolated or associated with extracardiac, especially neuromuscular disorders (NMDs). Many issues about LVHT are unclear. The review gives an update about pathomorphologic findings in patients >14 years and the role of NMDs in LVHT. Areas covered: A PubMed-search for the terms "noncompaction" or "non-compaction" or "hypertrabeculation" AND "autopsy" or 'biopsy' or 'ultrastructure' or 'electron microscopy' AND 'neuromuscular' or 'myopathy' or 'neuropathy' was carried out from 1985 to July 2018. Expert commentary: Macroanatomic (n = 65), histopathologic (n = 59) and ultrastructural (n = 7) reports were found. A comparison with echocardiography was described in 45 cases. Measurements of non-compacted and compacted layer were only given from hearts investigated in short-axis cuts after formaldehyde-fixation. Endocardial, subendocardial and interstitial fibrosis were frequent findings. When LVHT-patients were systematically investigated, a NMD was found in 80%, most frequently mitochondrial disorders, Barth syndrome, zaspopathy, and myotonic dystrophy type 1. LVHT does not seem to be a special type of cardiac involvement of NMDs. NMDs affect prognosis in LVHT as well as LVHT affects prognosis in patients with Duchenne muscular dystrophy.