New insights into left ventricular mechanics assessed by cardiac magnetic resonance and myocardial work analysis in non-compaction

Abstract

Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): 2 National Grants of the Romanian Ministry of Research and Innovation - UEFISCDI: "Heart Preserved" and "PRO HEART 3D. Background The so-called left ventricle non-compaction (LVNC), better described as excessive trabeculation, is a highly debated myocardial phenotype. One of the main debates is whether excessive trabeculation is a remodeling feature due to volume load and LV dilation, or is the primary cause of LV dysfunction with LV dilation in the advanced stages. Purpose We aim to evaluate the relationship of LV trabeculations with LV volumes and systolic function in patients with LVNC. Methods 50 patients with suspected LVNC were evaluated by cardiac magnetic resonance (CMR), transthoracic echocardiography (TTE), and N-terminal prohormone of brain natriuretic peptide (NTproBNP). To avoid over-diagnosis of LVNC, we analyzed 27 patients confirmed by CMR, with a positive Jacquier criterion [the percentage of non-compact myocardium mass (NCCM) >20%], excluding those having only a positive Petersen criterion. By CMR, we measured left ventricular end-diastolic volume index (LVEDVi), left ventricular end-systolic volume index (LVESVi), and left ventricular ejection fraction (LVEF). By TTE, we measured global longitudinal strain (GLS), and we performed myocardial work analysis (MWA), as a less afterload-dependent parameter than GLS, measuring global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE). Results Clinical and biological characteristics, CMR, GLS, and MWA results are detailed in Table 1. Mean percentage of NCMM was 29.45±10.3%. 89% of patients had HF, with LVEF ranging from 17% to 73%. There was no correlation between percentage of NCMM and LVEDVi. Instead, percentage of NCMM correlated positively with LVESVi (R=0.389, p = 0.045) and negatively with LVEF (R=-0.507, p = 0.007) (Figure 1). There was also no correlation between percentage of NCMM and GLS. Percentage of NCMM correlated negatively with GWE (R=-0.539, p = 0.004) (Figure 1), but not with GWI (p = 0.161), GCW (p = 0.249), or GWW (p = 0.060). By linear regression, per 10% increase in NCMM, LVEF decrease by 8.3% and GWE decrease by 4.2%. Percentage of NCCM had a trend to correlate positively with logNTproBNP (R=0.321, p = 0.103). Conclusions Our results suggest that excessive trabeculation in patients with LVNC is not a marker of chronic preload. LVNC seems to be a distinct cardiomyopathy, with a spectrum of systolic impairment proportional to the degree of hypertrabeculation. MWA is a promising tool to evaluate the functional implication of LV trabeculations.