Left ventricular noncompaction: a distinct cardiomyopathy or a trait shared by different cardiac diseases?

Abstract

Whether left ventricular noncompaction (LVNC) is a distinct cardiomyopathy or a morphologic trait shared by different cardiomyopathies remains controversial. Current guidelines from professional organizations recommend different strategies for diagnosing and treating patients with LVNC. This state-of-the-art review discusses new insights into the basic mechanisms leading to LVNC, its clinical manifestations, treatment modalities, anatomy and pathology, embryology, genetics, epidemiology, and imaging. Three markers currently define LVNC: prominent left ventricular trabeculae, deep intertrabecular recesses, and a thin compacted layer. Although new genetic data from mice and humans supports LVNC as a distinct cardiomyopathy, evidence for LVNC as a shared morphological trait is not ruled out. Criteria supporting LVNC as a shared morphological trait may depend on consensus guidelines from the multiple professional organizations. Enhanced imaging and increased use of genetics are both predicted to significantly impact our overall understanding of the basic mechanisms causing LVNC and its optimal management.

Keywords: compacted; epidemiology; genetics; imaging; pathology; trabeculae.

Central Illustration.. A Clinical Management Outline for Left Ventricular Noncompaction (LVNC).

Diagnosis and screening strategies for probands and relatives are listed in the left panel, clinical monitoring guides are listed in the middle panel, and treatment options are outlined in the right panel. Data for this table was selected from the Online Mendelian Inheritance in Man URL, established as a collaboration between the Institute of Genetic Medicine, Johns Hopkins Medicine, and the National Human Genome Research Institute.

Figure 1.. Two Hearts Depicting the Variability In Both Extension and Depth Of Trabeculae and Recesses

A) In this high magnification view of the apical wall of the heart, the noncompacted area is limited to a few apical trabeculae. The patient harbored mutations p.(Arg495Trp) in Myosin Binding Protein Cardiac 3 (MYBPC3) and p.(Asp117Asn) in Lim domain binding protein 3 (LDB3) genes [M_H+D O_H G_AD E_{G-MYBPC3[p.Arg495Trp]+LDB3 [p.Asp117Asn]}S_C-IV]. Although LBD3 is a candidate gene for LVNC, in this family, the disease segregated with the mutation in MYBPC3. B) In this heart, the prominent trabeculations (blue line) and deep recesses (red line) involve the entire LV apex. LV = left ventricle.

Figure 2.. High Magnification View of Intertrabecular (BLUE →) and Endocardial (GREEN→) Thrombotic Stratification.

Figure 3.. Echocardiographic 4-chamber views distinguishing prominent trabeculation (A) vs. hypertrabeculation (B).

(A) An echocardiographic 4-chamber view from a patient with a dilated cardiomyopathy presenting with prominent trabeculation in the LV apex and lateral wall. In this case the criteria for LVNC are not fulfilled. (B) An echocardiographic 4-chamber view from a patient with a typical LVNC presenting with hypertrabeculation in the LV apex and lateral wall. LV = left ventricle; LVNC left ventricular noncompaction.

Figure 4.. A) An echocardiographic image from a patient with LVNC.

An atypical 4-chamber view was used to better illustrate the non-compaction in the LV apex. B) The same view with color Doppler imaging. This view highlights perfusion of intertrabecular recesses from the left ventricular cavity. Abbreviations as in Figure 3.

Figure 5.. Cardiac magnetic resonance (CMR) from a patient with ischemic heart disease and ejection fraction = 27%.

Apart from the ischemic heart disease history, this patient does not meet the CMR criteria for LVNC cardiomyopathy. A) Short axis view showing the papillary muscle with prominent trabeculation in mid left ventricle segments. B) Long axis view showing trabeculation mainly in left ventricular lateral segments. Other abbreviations as in Figure 3.

Figure 6.. CMR from a patient with LVNC.

A) Short axis view showing the hypertrabeculation in all mid LV segments apart from the interventricular septum. B) Long axis view showing the hypertrabeculation mainly in the apical and mid LV segments. LV = left ventricular.