We read with great interest the report of Caselli et al. titled “Three-Dimensional Echocardiographic Characterization of Patients With Left Ventricular Noncompaction.” The authors demonstrated that real-time three-dimensional echocardiography (RT3DE) allows accurate measurement of the extent of noncompacted myocardium and the identification of patients with left ventricular (LV) noncompaction (LVNC). The study is interesting, but we think that a few additional comments on the usefulness of three-dimensional echocardiography in the evaluation of LVNC are necessary.
RT3DE is an emerging noninvasive diagnostic tool and is becoming part of everyday clinical practice worldwide. In recent studies, the role of RT3DE has been demonstrated in evaluating global and regional LV function. Unfortunately, only a limited number of RT3DE studies related specifically to LVNC are available at this time, and most are case reports. In a series of patients with LVNC, noncompacted and compacted LV segments had comparable increased three-dimensional regional volumes and reduced systolic function by RT3DE. These results could suggest that systolic LV dysfunction observed in LVNC is not confined to noncompacted LV segments. Moreover, Rajdev et al. demonstrated that both LV trabecular mass and the total number of trabeculations in patients with LVNC were underestimated significantly by two-dimensional transthoracic echocardiography compared with RT3DE.
It has also been confirmed that “en face” assessment of mitral annular size and function by RT3DE in healthy subjects and in patients with cardiomyopathy is accurate and well correlated with data acquired by magnetic resonance imaging. In a recent study with RT3DE, mitral annular enlargement and functional impairment were both present in a well-defined LVNC patient group, with a higher incidence and severity of mitral regurgitation. Moreover, left atrial (LA) ejection force, which is a characteristic of LV diastolic function and calculated from mitral annular size and the peak velocity of the mitral inflow A wave, was found to be increased in patients with LVNC compared to normal individuals. These results could demonstrate compensating LA work against the dysfunctional left ventricle in patients with LVNC.
Strain-based three-dimensional speckle-tracking echocardiography (3DSTE) also has been introduced. In addition to volume measurements, 3DSTE allows the quantification of LV strain, as well as rotational and twist characteristics. In a recent report, “rigid body rotation” (LV basal and apical rotation in the same direction), resulting in the near absence of LV twist, was demonstrated for the first time by 3DSTE in a patient with LVNC. Moreover, the usefulness of 3DSTE for the evaluation of LA volumes and function (LA ejection force) has been demonstrated in LVNC.
These initial studies could suggest the potential role of RT3DE and 3DSTE in the evaluation of the heart with LVNC. However, further studies are warranted to assess LV and LA volumes, mass, strain, rotation, twist, and synchronicity parameters in LVNC to better understand this interesting disease.