Left Ventricular Non-Compaction: A Rare Anomaly Presenting in Primary Care

Introduction

Left ventricular non-compaction (LVNC) is a rare cardiomyopathy that can present either with overt congestive heart failure or with minimal or no symptoms.^1,2 It is classified as an inherited genetic cardiomyopathy in 50% of the cases and can be sporadic in other cases. It is a result of intrauterine arrest of endomyocardial morphogenesis between five and eight weeks of life. LVNC is characterized by multiple prominent trabeculations with deep intertrabecular recesses resulting in thickened myocardium with two layers of compacted and non-compacted myocardium.¹ The following case represents a patient who presented with minimal symptoms in a primary care setting. 

Case Report

A 37-year-old Jamaican-American man presented for a routine primary care physical examination without a specific chief complaint. Incidentally on examination, a faint early systolic murmur was appreciated which prompted further inquiry about cardiopulmonary symptoms or the known presence of the murmur, the latter of which he denied. The patient, who was a soccer player and athlete, mentioned that over the last six months it had been increasingly difficult to complete his usual thrice weekly, 30-minute treadmill workout because of slight fatigue and mild dyspnea. He has no known heart or lung disease and denied any chest pain, pre-syncope, palpitations, diaphoresis or wheezing. He was a lifelong non-smoker and never used any illicit drugs. His apical point of maximal impulse was non-displaced and his pulses were strong, symmetric and regular. His vitals showed a normal blood pressure, pulse and oxygen saturation. Of note, his brother died at the age of 36 of unknown cardiac etiology. An ECG was obtained and revealed normal sinus rhythm with a normal axis and no ectopy, hypertrophy or ischemic changes. A transthoracic echocardiogram (Figure 1) was ordered to characterize the physiology of his murmur in the setting of decreased exercise tolerance. This revealed prominent trabeculations seen in the left ventricle representing non-compaction. A follow-up cardiac MRI (Figure 2) revealed a normal LV size and function with EF 56%, mild dilatation of his right atrium and right ventricle, and markedly increased trabeculations in the left ventricle from the mid ventricle to apex. The depth ratio of trabeculation: normal myocardium thickness supported a diagnosis of LVNC. A subsequent 24-hour Holter monitor revealed minimal and infrequent ectopy without occult arrhythmias. 

Discussion

This case represents a scenario of a minimally symptomatic patient with an incidental, and likely unrelated, murmur that prompted a cardiac work-up in the setting of mild decreased exercise tolerance. A subsequent LVNC diagnosis was made based on transthoracic echocardiography and cardiac MRI imaging. Given the rarity of this condition, appreciation for how to manage affected patients may present challenges for primary care providers. LVNC may be diagnosed in childhood and/or adulthood. Common presentations may include ventricular arrhythmias, symptoms of congestive heart failure, or systemic thromboembolic events.¹ LVNC is genetically heterogeneous with up to 50% of cases existing in individuals with affected family members. Two-dimensional echocardiography is the imaging modality of choice for diagnosis of the disease;³ however, cardiac MRI is warranted in cases where there are suggestive features of LVNC with technical limitation of ventricular views such as poor window, use of contrast, and misinterpretation of the images. Currently, there are three criteria for echocardiography (Chin, Jenni, and Stöllberger) and two for CMRI (Petersen and Jacquier) that can be used in the diagnosis of LVNC, all of which have not been validated in a large patient cohort.⁴ A study by Sandhu et al⁵ found increasing rates of LVNC when retrospectively reviewing echocardiograms using the various criteria. They found a 3.7% prevalence in probable or definite LVNC diagnosed patients with ejection fractions below 45% and an overall 0.26% prevalence in undiagnosed patients who were referred for an echocardiogram for dyspnea, chest pain or congestive heart failure over one year in a large medical center.⁴ Several additional studies have demonstrated poor correlation between the existing diagnostic criteria.^6,7 Incidental discovery of LVNC may result from echocardiography as demonstrated in this case, where the patient presented in primary care with mild symptoms discovered on review of systems in the setting of a newly discovered murmur. Recently, Thavendiranthan et al⁴ suggested that if the echocardiogram quality is optimal, the Jenni LVNC diagnostic criteria are preferred; however, poor quality images should be followed up with a cardiac MRI or contrast echocardiogram for confirmation. There are no consensus criteria on diagnosis of LVNC, which can lead to diagnostic and therapeutic management challenges. Nevertheless, early accurate diagnosis can be difficult to establish, which may delay management.

Current treatment options are largely based on symptoms and include the use of aspirin, ACE inhibitors, and/or pacemakers/defibrillators — the latter indicated for individuals deemed to be at high risk for cardiac arrhythmias. Asymptomatic patients may undergo serial echocardiographic monitoring to evaluate for disease progression. Given the high familial penetrance, it is recommended that first-degree relatives of patients with LVNC undergo cardiac evaluation once diagnosis is confirmed; however, genetic screening is not warranted due to heterogeneity.⁸ Furthermore, it is suggested that oral anticoagulation be initialed for primary or secondary prevention in patients who have atrial fibrillation, severe systolic dysfunction or intraventricular thrombus formation. Resultant arrhythmias and/or congestive heart failure treatment should be treated independently according to most current respective evidence-based guidelines.² 

There remain several unanswered questions for LVNC despite the increasing appreciation of this disorder. As increasing cases are identified, future studies will hopefully delineate consensus guidelines for LVNC diagnosis, which will lead to timely identification and early treatment or monitoring. Asymptomatic patients with LVNC will most likely present in primary care; therefore, increased awareness of this rare but clinically significant cardiomyopathy is imperative for preventative and targeted therapy as well as for identification of potentially affected family members.

Disclosure: The authors have no conflicts of interest to report regarding the content herein.   

References

1. Fox EH, Wood ML, Trotter J, Moore C. New onset heart failure in a 29-year-old: A case report of isolated left ventricular noncompaction. South Med J. 2006;99(10):1130-1133.
2. Finsterer J. Left ventricular non-compaction and its cardiac and neurologic implications. Heart Fail Rev. 2010;15:589-603.
3. Jayan P, Shankarappa RK, Ananthakrishna R, Nanjappa MC. Isolated left ventricular noncompaction mimicking ventricular mass. Echocardiography. 2011;28:137-139.
4. Thavendiranathan P, Dahlya A, Phelan D, Desai MY, Tang WH. Isolated left ventricular non-compaction controversies in diagnostic criteria, adverse outcomes and management. Heart. 2013;99:681-689. 
5. Sandhu R, Finkelhor RS, Gunawardena DS, Bahler RC. Prevalence and characteristics of left ventricular noncompaction in a community hospital cohort of patients with systolic dysfunction. Echocardiography. 2008;25:8-12.
6. Stanton C, Bruce C, Conolly H, et al. Isolated left ventricular noncompaction syndrome. Am J Cardiol. 2009;104:1135-1138.
7. Murphy RT, Thaman R, Blanes JG, et al. Natural history and familial characteristics of isolated left ventricular non-compaction. Eur Heart J. 2005;26:187-192.
8. Hershberger RE, Lindenfeld J, Mestroni L, et al. Genetic evaluation of cardiomyopathy--a Heart Failure Society of America practice guideline. J Card Fail. 2009;15:83-97.