|Ahead of print publication
Magnetic resonance imaging findings in a rare case of left ventricular noncompaction
RA George1, Anil Kumar2, Navreet Singh3, Sangeet Kumar1
1 Department of Radiodiagnosis and Imaging, Command Hospital, Chandi Mandir, Haryana, India
2 Department of Cardiology, Air Force Hospital, Kanpur, Uttar Pradesh, India
3 Department of Cardiology, Command Hospital, Chandi Mandir, Haryana, India
|Date of Submission||11-May-2020|
|Date of Decision||21-Jun-2020|
|Date of Acceptance||22-Sep-2020|
|Date of Web Publication||10-May-2021|
Department of Radiodiagnosis and Imaging, Command Hospital, Chandi Mandir - 134 107, Haryana
Source of Support: None, Conflict of Interest: None
Left ventricular noncompaction (LVNC) is a relatively rare clinical entity with a grave outcome. Various morphological findings, both on two-dimensional echocardiography and cardiac magnetic resonance imaging (MRI), have been depicted in the literature, helping in establishing the correct diagnosis of this condition. We describe a rare case of LVNC and its MRI features.
Keywords: Cardiac MRI, genetic cardiomyopathies, left ventricular noncompaction, spongy myocardium
| Introduction|| |
Left ventricular noncompaction (LVNC) is a rare clinical entity characterized by a thin compacted outer epicardial layer and prominent inner ventricular trabeculae having deep intertrabecular recesses that are continuous with the left ventricular (LV) cavity. LVNC has been described as genetic cardiomyopathy (CMP) by the American Heart Association and as a nonclassified entity by the European Society of Cardiology.
| Case Report|| |
A 25-year-old female presented with complaints of recurrent jaundice, pain abdomen, and progressive easy fatiguability (NYHA I to II) for a 3-month duration. Clinical and laboratory evaluations revealed tachycardia (heart rate 90/min), leukocytosis (total leukocyte count 28,200/cmm, with left shift), and raised hemoglobin level. Pelvic ascites and left-sided pleural effusion were noted on ultrasonography.
Two-dimensional (2D) echocardiography (Philips EPIC 7) revealed dilated CMP with LV ejection fraction of 15%–20%. Two distinct myocardial layers were seen [Figure 1], with the inner echogenic spongy layer having a maximum thickness of 18 mm, showing multiple trabeculations with blood flow within. An outer relatively hypoechoic layer measuring 9 mm in maximum dimension was also seen, with global hypoplastic valves. No evidence of left atrial/ventricular clot was seen. The cardiac apex was not completely visualized.
|Figure 1: Two-dimensional echocardiographic images through the left atrium and left ventricle, showing two distinct layers of the myocardium. The inner noncompacted spongy layer (depicted by ) showing trabeculations and outer more echogenic compact layer (depicted by ) ratio of noncompact to compact layer was 2|
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Cardiac MRI was done (Philips Achieva 1.5 Tesla) using electrocardiogram-gated HASTE T2 axial, coronal, and sagittal sections for screening. This was followed by the LV long-axis view, short-axis view, and four-chamber view in both black blood (TR 1875.0 s and TE 30.7 s) and white blood techniques (TR 3.4 s and TE 1.7 s). Imaging findings confirmed the presence of two distinct layers in the LV myocardium, seen predominantly in its posterolateral wall and apex with relative sparing of the interventricular septum. The inner layer appeared discontinuous and showed multiple trabeculations projecting into the cardiac lumen [Figure 2] and showing direct communication [Figure 3]. The maximum end-systolic thickness of this inner layer was 14 mm. There was an outer thin “compact” myocardial layer with an end-systolic measurement of 5.5 mm in thickness. With the ratio of noncompact to compact layer measuring 2.54, the diagnosis of “noncompaction cardiomyopathy” of the left ventricle was confirmed by cardiac magnetic resonance imaging (MRI).
|Figure 2: Cardiac magnetic resonance imaging, short-axis view in “black-blood” technique showing two distinct myocardial layers in the left ventricle with enlarged inner layer showing multiple prominent trabeculations (depicted by ) and an outer compact hyperintense layer (depicted by |
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|Figure 3: Cardiac magnetic resonance imaging short-axis view in “whiteblood” technique showing deep intertrabecular recesses communicating with the left ventricular cavity (depicted by |
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| Discussion|| |
LVNC, also known as “spongy myocardium,” is a rare congenital CMP. It is a comparatively newly recognized clinical entity with the first mention in literature in 1975 associated with congenital cardiac anomalies of the pediatric population. Antemortem diagnosis of LVNC using 2D echocardiography was first made in 1984, when Engberding and Bender demonstrated a spongy myocardium with prominent sinusoids. They attributed these persistent sinusoids to abnormal lack of sinusoidal regression during cardiac embryogenesis.
The reported prevalence rate of LVNC is 0.014%–0.05% of adults and occurs more in men. The spectrum of symptoms is wide and nonspecific ranging from asymptomatic patients to those presenting with heart failure and arrhythmias. Fatal complications such as embolic events, arrhythmias, and sudden death have been reported. The diagnosis in a clinically suspicious patient is based on imaging findings using different techniques such as echocardiography, cardiac MRI, or multidetector computed tomography (MDCT).
The pathogenesis of LVNC has been ascribed to failure of myocardial compaction during fetal development. Trabeculations are normally present before the establishment of coronary arteries, to allow for a greater surface to volume ratio, helping in myocardial perfusion. By the end of 10 to 12 weeks, there is a compaction of these trabeculations to form majority of the ventricular volume. The process of compaction continues in the postnatal life till the final process of development of the spiral pattern of myocardium occurs. The arrest of this normal compaction process leads to the development of highly trabeculated myocardium.
Initially, this disease entity was thought of as a pure congenital condition, with multiple genes identified, namely Fbkp1a/Notch, G4.5 gene/TAZ protein, 14-3-3 deletion, ZASP protein, TNNT2 protein, MYH7 protein, TPM1 protein, MYBPC3 protein, and ACTC1 protein. There are reports of LVNC being an acquired condition in patients with neuromuscular disorders such as myotonic dystrophy. LVNC can either be isolated or associated with coronary artery anomalies, conotruncal anomalies (absence of the pulmonary valve, pulmonary atresia, and tricuspid atresia), Ebstein anomaly, transposition of the great arteries, pulmonic stenosis, ventricular septal defect, atrial septal defect, and hypoplastic heart syndrome.
Echocardiography is the first-line diagnostic tool for LVNC. The previous studies have used end-systolic ratio between compacted and noncompacted myocardium >2 in the short-axis view as diagnostic. However, limitations such as operator dependence, nonvisualization of the apex, false-negative reports in case of nonvisualization of myocardium trabeculations, and failure to acquire true “short-axis” view perpendicular to the LV long axis limit its usage. The advent of contrast enhancement in echocardiography has augmented its diagnostic sensitivity.
Cardiac MRI is performed with dual aims of confirming the diagnosis and to evaluate for associated congenital diseases. Sequences such as balanced steady-state free precession in orthogonal planes can clearly depict the two-layered myocardium. The added advantage of MRI includes multiparametric view, volumetric analysis, depiction of concomitant pathologies, nonoperator dependence, global visualization of the heart, and visualization of myocardium even in the end-diastolic state. According to established diagnostic standards, individuals are categorized as having noncompaction if either the end-systolic noncompaction-to-compaction ratio is more than 2 or the end-diastolic noncompaction to compaction ratio is more than 2.3. However, end-systolic noncompaction-to-compaction ratios >2 have been found to have stronger prediction for LV function or for identifying clinical heart failure. The short-axis view is helpful when trabeculations are measured in mid-cavity and basal segments; however, for the apical segment, it produces spurious morphological appearance of prominent trabeculations rendering four-chamber views more helpful for that region. There have been ancillary quantitative criteria proposed for differentiating LVNC from other cardiomyopathies. More than 20%–25% of global LV mass being trabeculated is highly sensitive and specific for the diagnosis of LVNC. Isolated involvement of the right ventricle remains controversial with only few isolated cases reported in the literature. The role of delayed enhancement MRI has been found restricted to the evaluation of subendocardial fibrotic foci, which are independent risk factors for lethal arrhythmias.
MRI has limitations in terms of (a) time to complete the examination and requires breath-holding that pose challenges to some patients and (b) inability to image patients with some devices/implants. As an alternative, MDCT uses ionizing radiation and has lower capability to characterize myocardial tissue which limits its application as a primary diagnostic modality. However MDCT has an added advantage in evaluating coronary arteries and thus, can be of utility in diagnosis of Coronary Artery Disease (CAD) as etiology for LVNC.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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