Mitral regurgitation in left ventricular noncompaction cardiomyopathy assessed by cardiac MRI

Previous case reports have described patients with left ventricular noncompaction cardiomyopathy (LVNC) with significant mitral regurgitation (MR). The study aim was to determine if LVNC is associated with MR, as assessed by cardiac magnetic resonance imaging (cMRI).

LVNC, assessed with cMRI, was observed retrospectively among 122 consecutive cases, 31 of whom had an end-systolic noncompacted-to-compacted ratio (ESNCCR) ≥ 2. In addition, 40 normal subjects undergoing cMRI and 40 with moderate to severe MR were included as controls. Using cine images, the ESNCCR and left ventricular (LV) and right ventricular (RV) stroke volumes were measured. The mitral regurgitant fraction (MRF) was calculated by dividing the difference between the RV and LV stroke volumes by the LV stroke volume. The total papillary muscle (TPM) area was measured from the mid short-axis view. Adjusting for age, race, gender and body surface area, an analysis of covariance was conducted to determine whether MRF and TPM were associated with ESNCCR ≥ 2. Adjusted means were presented with 95% confidence intervals.

After adjustment, the MRF in patients with ESNCCR ≥ 2 was higher than in controls, but did not differ from that in patients with significant MR (21 ± 6.5% versus 2.7 ± 12% versus 29.2 ± 11%, p = 0.039 and p = 0.3, respectively). Further, patients with ESNCCR ≥ 2 had a lower TPM than normal controls or those with moderate to severe MR (1.89 ± 0.28 cm2 versus 3.6 ± 0.26 cm2 versus 3.7 ± 0.24 cm2; p < 0.001 and p < 0.001, respectively).

LVNC is associated with increased MR, as assessed using cMRI. LVNC is also associated with abnormalities in the papillary muscle anatomy, which may predispose to MR.