Pathomorphologic findings in left ventricular hypertrabeculation/noncompaction of adults in relation to neuromuscular disorders.

Background: Aim of this study was to assess pathomorphologic findings (PATHO) in patients with echocardiographically (ECHO) diagnosed left ventricular hypertrabeculation/noncompaction.

Methods: ECHO-criteria for LVHT were: >3 trabeculations, moving synchronously with the compacted myocardium, and forming the noncompacted part of a two-layered myocardium. At autopsy, the hearts were investigated according to the pathologists' preferences.

Results: Twelve patients (2 females, age 27-81 years) were included. Seven suffered from neuromuscular disorders, 5 patients were not investigated neurologically. The specimens were acquired after explantation during heart transplantation (n=1), death due to heart failure (n=6), sudden death (n=2), pneumonia (n=2) and stroke (n=1). Eight hearts were investigated without fixation and 4 after formaldehyde fixation. The hearts were opened along the long-axis, in 3 hearts additional short-axis cuts were carried out. At PATHO the trabecular meshwork was better visible in the formaldehyde-fixed hearts than in the fresh hearts. Differentiation from papillary muscles was easier on the long-axis cuts, whereas the two-layered structure was better visible on short-axis cuts. The trabecular pattern was similar in patients with neuromuscular disorders and those who did not undergo neurologic investigation. Subendocardial fibrosis was found in each case. Due to the complex three-dimensional geometry, it was impossible to count the number of trabeculations.

Conclusion: Formaldehyde-fixation should be performed when comparing ECHO with PATHO findings in LVHT. Long-axis as well as short-axis cuts should be carried out in order to assess the course of trabeculations and the extent of the two-layered structure. Subendocardial fibrosis in LVHT deserves further research.