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Dilated Left Ventricular Cardiomyopathy Secondary to Noncompaction in a Patient with Paroxysmal Atrial Fibrillation

John Chin, MD, Daniel Seidensticker, MD, and Andrew Lin, MD

Volume 55 - Issue 11 - November 2015

Authors:
John Chin, MD; Daniel Seidensticker, MD; and Andrew Lin, MD

Citation:
Consultant. 2015;55(11):949-950

 

A 44-year-old man with a history of paroxysmal atrial fibrillation (PAF) and New York Heart Association (NYHA) class III heart failure with a reduced ejection fraction (HFrEF) was admitted to our hospital for dofetilide loading in the setting of a 10-month history of progressively decreasing exercise capacity secondary to PAF.

History. At admission, the etiology of the patient’s HFrEF was unclear, with his most recent transthoracic echocardiogram (TTE) demonstrating an EF of 25% to 30%. A prior CT angiogram (CTA) had demonstrated normal coronary arteries, reducing the likelihood of ischemia being the culprit of his HFrEF. The patient had no family history of cardiovascular disease and was medically optimized with carvedilol 25 mg twice daily, losartan 100 mg once daily, and furosemide 40 mg once daily, with spironolactone 25 mg once daily added upon admission. Despite a CHA2DS2-VASc score of 2 and strong recommendations from his cardiologist, the patient continually declined anticoagulation therapy.

While admitted to the cardiology service, other than 2 isolated episodes of asymptomatic, nonsustained, monomorphic, ventricular tachycardia and appropriate dose adjustments for prolonged corrected QT interval, the patient responded well to the dofetilide and converted to normal sinus rhythm.

Diagnostic tests. A left and right heart catheterization revealed normal coronary arteries and normal right heart pressures. An inpatient TTE, however, demonstrated an EF estimated at 40%. Cardiac magnetic resonance imaging (cMRI) revealed an EF of 27% (calculated on both short-axis and 4-chamber view, Figures 1 and 2, respectively), along with prominent trabeculation at the cardiac apex and portions of the septal wall weighing approximately 171 g; these findings had not been visualized on TTE.

The ratio of noncompacted to compacted myocardium was approximately 2.6. The left ventricle dilated to a maximal end-diastolic dimension of 68 mm and a maximal end-diastolic volume of 226 mL. The left ventricle showed normal thickness, measuring 9 mm at the anteroseptal wall and 11 mm at the posterior lateral wall. MRI also demonstrated myocardial delayed enhancement at the anterior midventricle wall to the apex, as well as at the septum and apex. The right ventricle was normal in size and demonstrated preserved global systolic function without segmental wall motion defects.

Diagnosis. Ultimately, isolated left ventricular noncompaction (ILVNC) was believed to be the etiology of the patient’s nonischemic dilated left ventricular cardiomyopathy. The patient was discharged from the hospital with dofetilide for antiarrhythmic control of his PAF, as well as a life vest pending placement of an implantable cardioverter-defibrillator (ICD).

Discussion. ILVNC, a result of premature arrest of intrauterine myocardiogenesis, is characterized by prominent trabeculae, deep intertrabecular recesses, and thickening of the myocardial wall into 2 distinct layers consisting of a thin epicardial compacted zone and an extremely thick endocardial noncompacted zone.1-15 These characteristics give the myocardium a spongy appearance.5,14

Once thought to be rare, ILVNC has become more prevalent in a subset of the population with HF; as such, it may necessitate classification as a distinct cardiomyopathy by the World Health Organization.1,4,5

The major clinical manifestations of this condition include HF, ventricular arrhythmias, and thromboembolic events.1,6-8 Recent research suggests that demand ischemia resulting from the failure of the coronary microcirculation to supply the noncompacted ventricular endocardium, and fibrosis of the trabeculations, may lead to systolic dysfunction and arrhythmogenesis.4,6,7,9 The main focus of research is not only on the development of diagnostic imaging criteria with echocardiography and possibly cMRI, but also on the development of a classification scheme to assess the severity of ILVNC as it correlates to systolic dysfunction.1,2,10-12

Diagnostic criteria with echocardiography proposed by Jenni and colleagues12 include:

  1. The absence of coexisting cardiac abnormalities.
  2. A 2-layered structure of the left ventricular wall, with the end-systolic ratio of noncompacted to compacted layer greater than 2 (short axis view).
  3. Structural predominance in the apical and midventricular areas.
  4. Blood flow directly from the ventricular cavity into the deep intertrabecular recesses noted with echocardiography with color Doppler flow. 

Echocardiography with color Doppler flow is the modality of choice for diagnosing ILVNC, with the use of intravenous contrast for better delineation of the endocardium not visible with standard imaging.11 No evidence suggests the applicability of echocardiographic criteria to cMRI, with magnetic resonance reserved for cases in which echocardiography images are equivocal,9,10 as was the case with our patient.

Once images of the cardiac chambers have been obtained, the ratio of the noncompacted to compacted myocardium, as well as the area of noncompaction, can be used objectively to classify the severity of the cardiomyopathy; in fact, Belanger and colleagues2 showed that a ratio of 2 or more and an area of 5.0 cm2 or greater were associated with worse left ventricular systolic function. Stacey and colleagues8 also concluded that cMRI demonstrating a noncompacted to compacted ratio of 2 or greater with hypertrabeculation was strongly associated with adverse clinical outcomes. These correlations were evident in our patient, who had a ratio of 2.6 and NYHA class III HFrEF. Although our patient had normal right ventricular function, it should be noted that for individuals with a noncompacted to compacted ratio of 2 or greater, a reduced right ventricular EF is independently associated with adverse events of ILVNC.8

Genetic heterogeneity has been proposed as a possible cause for the similar clinical features between ILVNC and idiopathic dilated cardiomyopathy, which ultimately suggests ventricular dysfunction rather than the presence of noncompacted myocardium as the cause of increased mortality risk.1,3-5,13,14

Currently, there is no defined treatment for ILVNC. Rather, the aim is to treat the clinical manifestations of the disease—mainly HF, ventricular arrhythmias, and thromboembolic events.1-4,6-9,13,14 Although our patient displayed several poor prognostic markers (PAF and NYHA class III HFrEF), he was continually optimized with beta-blockers and angiotensin receptor blockers, as well as with aldosterone antagonists and diuretics.

ILVNC by itself is not a risk factor for stroke or embolism.15 Clot formation within the intertrabecular recesses can lead to cardioembolic events when associated with underlying systolic dysfunction and the presence of atrial tachyarrhythmia.6,9 Although our patient’s rhythm-controlled with dofetilide and subsequently converted to normal sinus rhythm, the addition of hypertrabeculation and severe systolic dysfunction increases his risk for thromboembolism; despite our best efforts, the patient remained adamant about refusing anticoagulation therapy. Given the risk of sudden cardiac death in this patient population, ICD placement also should be seriously considered.6,9 Offering screening to family members of individuals with ILVNC is important, since early detection can help identify asymptomatic patients who are at risk for future complications.9,13

Outcome of the case. Our diagnosis of nonischemic dilated cardiomyopathy secondary to isolated left ventricular noncompaction was based primarily on the morphologic appearance and noncompacted to compacted ratio of the myocardium on cMRI, which is not necessarily in accord with current proposed echocardiographic diagnostic criteria. This patient carries several poor prognostic factors, mainly concomitant PAF and NYHA class III HFrEF. ILVNC alone makes him susceptible to progressive decline of systolic function; however, with a component of PAF without anticoagulation, he is exponentially more prone to thromboembolic events. It is our hope that with maximal medication optimization and eventual ICD placement, we can further limit the clinical complications of systolic dysfunction, ventricular tachyarrhythmia, and thromboembolic events.

References:

  1. Stanton C, Bruce C, Connolly H, et al. Isolated left ventricular noncompaction syndrome. Am J Cardiol. 2009;104(8):1135-1138.
  2. Belanger AR, Miller MA, Donthireddi UR, Najovits AJ, Goldman ME. New classification scheme of left ventricular noncompaction and correlation with ventricular performance. Am J Cardiol. 2008;102(1):92-96.
  3. Roberts WC, Karia SJ, Ko JM, et al. Examination of isolated ventricular noncompaction (hypertrabeculation) as a distinct entity in adults. Am J Cardiol. 2011;108(5):747-752.
  4. Sakuma M, Hayashi T, Kamishirado H, Akiya K, Takayanagi K, Morooka S. Isolated noncompaction of the left ventricular myocardium in an elderly patient. Circ J. 2004;68(10):964-967. 
  5. Moric-Janiszewska E, Markiewicz-Łoskot G. Genetic heterogeneity of left-ventricular noncompaction cardiomyopathy. Clin Cardiol. 2008;31(5):201-204.
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  8. Stacey RB, Andersen M, Haag J, et al. Right ventricular morphology and systolic function in left ventricular noncompaction cardiomyopathy. Am J Cardiol. 2014;113(6):1018-1023.
  9. Chrissoheris MP, Ali R, Vivas Y, Marieb M, Protopapas Z. Isolated noncompaction of the ventricular myocardium: contemporary diagnosis and management. Clin Cardiol. 2007;30(4):156-160.
  10. Stöllberger C, Kopsa W, Tscherney R, Finsterer J. Diagnosing left ventricular noncompaction by echocardiography and cardiac magnetic resonance imaging and its dependency on neuromuscular disorders. Clin Cardiol. 2008;31(8):383-387.
  11. de Groot-de Laat LE, Krenning BJ, ten Cate FJ, Roelandt JR. Usefulness of contrast echocardiography for diagnosis of left ventricular noncompaction. Am J Cardiol. 2005;95(9):1131-1134.
  12. Jenni R, Oechslin E, Schneider J, Attenhofer Jost C, Kaufmann PA. Echocardiographic and pathoanatomical characteristics of isolated left ventricular non-compaction: a step towards classification as a distinct cardiomyopathy. Heart. 2001;86(6):666-671.
  13. Greutmann M, Mah ML, Silversides CK, et al. Predictors of adverse outcome in adolescents and adults with isolated left ventricular noncompaction. Am J Cardiol. 2012;109(2):276-281.
  14. Watkins H, Ashrafian H, Redwood C. Inherited cardiomyopathies. N Engl J Med. 2011;364(17):1643-1656.
  15. Chin TK, Perloff JK, Williams RG, Jue K, Mohrmann R. Isolated noncompaction of left ventricular myocardium: a study of eight cases. Circulation. 1990;82(2):507-513.