Abstract 3421: Tissue Doppler Imaging and Magnetic Resonance in Isolated Left Ventricular Non-Compaction: Functional Assessment in a Paediatric Population
Background: Isolated LV non-compaction (ILVNC) is a poorly defined condition with an uncertain outcome. Whilst the distribution of non-compaction has been previously described, the relationship of these structural changes with regional functional derangement is unclear.
Methods: We prospectively investigated patients (pts) by magnetic resonance imaging (MRI; Siemens 1.5T Avanto) and echocardiography (Philips iE33). All pts had a ratio of non-compacted myocardium to compacted myocardium ≥ 2:1 at end-systole by echo and at end-diastole by MRI. The number and distribution of non-compacted segments was based on the 17 segment model. MRI was performed using turbo spin echo, truFISP cine, and delayed enhancement breath hold sequences in standard planes. Transthoracic echo (TTE) was performed in apical long axis and parasternal short axis views. Pulse wave tissue Doppler imaging (TDI) was performed at the mitral valve annulus from an apical 4 chamber view. Colour TDI was performed in an apical 4 chamber view to assess strain (ε) and strain rate (SR) in the basal and mid-ventricular segments. Imaging parameters were optimised to achieve frame rates >180/sec.
Results: The mean age was 16.5 years (n=8). Of a potential 136 segments, 111 (82%) and 136 (100%) were visualized on echo and MRI respectively. Of these, 32 segments (32/111; 29%) showed non-compaction on echo and 49 segments (49/136; 36%) on MRI. No pt had evidence of fibrosis on delayed enhancement imaging. Global LV systolic function was impaired in 6 pts (EF < 55% and reduced s-wave velocity). Diastolic impairment was evident in 2 of these 6 pts. Marked heterogeneity of regional function, with depressed ε and SR, in addition to passive lengthening in some segments, was observed in all patients including those with normal global systolic function. These areas did not necessarily coincide with segments with non-compacted myocardium.
Conclusions: Cardiac MRI is more sensitive than TTE in the diagnosis of ILVNC. Regional abnormalities of contraction detected by ε and SR imaging are not confined to non-compacted segments. There was no evidence of fibrosis on delayed enhancement imaging to account for contractile dysfunction. These findings may have important implications for the management of pts with ILVNC.