Left ventricular noncompaction - the impact of the diagnostic method.

What is it about?

Left ventricular noncompaction (LVNC) is so far considered to be a unique inherited cardiomyopathy. It is characterized by a spongy morphological appearance of left ventricular (LV) myocardium with a mesh of prominent trabeculae separated by deep intertrabecular recesses. The LV hypertrabeculation, however, can be present in healthy individuals, as well as in cardiomyopathies. Clinically, LVNC is associated with an increased risk of cardiovascular events similar to non-ischemic dilative cardiomyopathy (nDCM). The LV end-diastolic volume (EDV) and ejection fraction (EF) may be the significant markers of adverse outcomes in LVNC. In turn, the clinical significance of the LV hypertrabeculation is unclear, and some studies indicate that it is not a prognostic factor of adverse cardiovascular outcomes. These observations may be related to the variety of different criteria for LVNC recognition using cardiac magnetic resonance (CMR) imaging. They are mostly based on the estimation of a thickness ratio between LV noncompacted and compacted layers or of a mass ratio between an LV noncompacted myocardial mass (NCM) and total LV mass (LVM). The methods assessing the mass ratio differ in the approach of in- or exclusion of intertrabecular blood pool (ITB) and papillary muscles (PMs) from NCM. Such an approach may affect the LVNC diagnosis and the assessment of the influence of LV hypertrabeculation on EDV and EF.

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Photo by nadhem benmbarek on Unsplash

Photo by nadhem benmbarek on Unsplash

Why is it important?

Our study aimed to compare the two different CMR methods of measurement of NCM and its percentage of LVM, namely the most frequently used, proposed by Jacquier et al. and novel proposed by Hautvast’s computed algorithm, and to evaluate their possible impact on EDV and EF. The Hautvast’s algorithm enables differentiating ITB from NCM and is currently available as part of Philips’ proprietary analysis software for the LV volumes and mass. Jacquier’s method of LVNC recognition adds ITB into NCM, which might falsely augment the real estimate of the latter. Additionally, it gives a possibility to include PMs either into the LV compacted layer mass (CLM) or into the LV trabeculation area if not clearly distinguished. Such a non-uniform approach to NCM estimation may decrease its reproducibility, as PMs in LVNC are often multiple and fragmented, and hence, their inclusion in either of the two layers can be equivocal. An algorithm differentiating ITB from NCM was proposed and described by Hautvast et al. [12] and is currently available as part of Philips’ proprietary analysis software for the LV volumes and masses. This algorithm enables the exclusion of ITB from NCM, but so far, its value in LVNC diagnosis was not confirmed.

Perspectives