Left ventricular noncompaction (LVNC) is a rare disorder that is variably classified as a primary genetic cardiomyopathy (CM) by the American Heart Association.1 It is mostly believed to be a congenital abnormality, characterized by the arrest of the typical embryonic myocardial maturation process with the subsequent retention of the trabecular myocardial structure, which defines the early embryonic heart.2
During very early embryonic development, the left ventricular (LV)myocardium is composed of a loose network of fibers separated by deep recesses, which link it with the LV cavity. At 8 weeks of prenatal development, gradual compaction of these fibers occurs, and LVNC is thought to result from the arrest of this normal process.2,3 Significant variability in myocardial involvement exists, ranging from panventricular to isolated apical involvement, likely related to time of arrest of this maturation process.4 The decreased contractile capability and inadequate epicardial coronary system communication of this trabecular endocardium is thought to lead to the clinical manifestations of LVNC.1-7
This report describes the case of a 45-year-old male soldier who presented with a unique case of heart failure, diagnosed via cardiac magnetic resonance imaging (MRI).
Case Study
The patient presented to the San Antonio Military Medical Center emergency department in mid-2011 with increasing dyspnea for several weeks. He also reported significant lower-extremity and scrotal edema. Although the patient had been previously healthy, his recent medical history was remarkable for a severe combat injury suffered while on duty with the U.S. Army in Afghanistan: He was involved in an explosion from an improvised explosive device in August 2009. He was medically evacuated to the U.S., where he required multiple hospitalizations and surgeries. Prior to his current presentation, the patient had been briefly hospitalized for hospital-acquired pneumonia. During this hospitalization, he first noted abnormal swelling of his legs, a finding that was initially attributed to the large sodium load he had received with his IV antibiotics.
DIAGNOSIS
The patient’s vital signs on presentation were notable for 100/83 mm Hg blood pressure, 103 beats per minute (bpm) heart rate, and 18/min respiratory rate with a saturation of 100% on 4 liters of oxygen by nasal cannula. He was conversant but tachypneic and had to pause frequently to catch his breath. His neck veins were notably distended with jugular venous pulsations visible to the angle of the jaw with the patient at 30 degrees. His heart sounds were normal without an S3, but his lungs were notable for bilateral crackles over the lower- to mid-lung fields. He had profound bilateral upper and lower extremity and scrotal pitting edema. He had no lymphadenopathy or skin rashes.
On presentation, the patient’s laboratory results were remarkable for a 444 pg/mL brain natriuretic peptide. A chest X-ray revealed bilateral basilar opacities. An electrocardiogram showed normal sinus rhythm (70 bpm), with normal axis and poor R-wave progression across the precordium. An echocardiogram was performed and notable for a moderately dilated left ventricle with severely depressed systolic function of 10% to 15%, and elevated pulmonary artery pressures. Subsequently, the patient was referred for a coronary angiography, which showed no evidence of coronary atherosclerosis. A cardiac MRI was then performed to evaluate for nonischemic CM, which revealed prominent trabeculations in both ventricles, but most notably in the left ventricle, consistent with a diagnosis of LVNC.
The patient was treated with diuretics, beta-blockers, and an angiotensin-converting enzyme (ACE) inhibitor with improvement in his heart failure symptoms. He was started on systemic anticoagulation with warfarin for his severely depressed LV function. His hospital course was complicated by frequent, nonsustained ventricular tachycardia (VT), and he was referred to the electrophysiology service for implantation of an automated intracardiac cardioverter/defibrillator (AICD) for primary prevention of sudden cardiac death. His clinical course was otherwise unremarkable, and he was discharged after 8 days with complete resolution of his symptoms.
Discussion
The clinical presentation of LVNC is typically due to complications of ventricular dysfunction, including heart failure, arrhythmias, and cardioembolic events. Retrospective studies have shown much variability in the frequency of these complications, likely due to selection bias in earlier studies. These earlier studies had suggested a frequency of heart failure > 50%, but recent studies have shown a more modest frequency of 30% to 35% of affected patients.
Even greater variance has been found in the frequency of arrhythmias, but most studies have shown a frequency of at least 20% for VT. Poor blood flow in the deep intertrabecular recesses in patients with LVNC is additionally thought to lead to a predisposition for mural thrombus formation with an elevated frequency of systemic embolic events, ranging from 5% to 20% among previous studies.1-4,6,8
