Noncompaction of the Left Ventricle – A Rare Cause Of Non-ischemic Cardiomyopathy

Author: M. Auron, M.D, Department of Hospital Medicine, Cleveland Clinic
Reviewer: V. Dimov, M.D., Department of Hospital Medicine, Cleveland Clinic

A 56 yo AAM with no significant past medical history presented to the ER with progressive dyspnea, epigastric pain and diaphoresis for one week.

Medications:
None

Physical examination:
Bibasilar rales; irregular heart rate, S3 gallop, displaced PMI and pedal edema.

What is the most likely diagnosis?
Acute heart failure; rule-out MI.

What tests would you order?
Transthoracic echocardiogram, chest roentgenogram, cardiac enzymes (troponin I, CK, CK MB), BNP, EKG.

Initial laboratory results:
CK 100 ng/ml, CK-MB 2.2 ng/ml, Troponin I 1.9 ng/ml.

EKG showed left bundle branch block with no ST changes.

What treatment would you start for this patient?
Presumptive diagnosis of NSTEMI was established and initial treatment included beta-blockers, oral acetyl-salicylic acid, heparin, tirofiban and furosemide.

What happened?
The patient underwent a cardiac catheterization that showed normal coronary arteries. An echocardiogram showed LVEF of 20% and increased trabeculation noted in the LV apex and posterolateral walls suggestive of non-compaction. Secondarily to multiple episodes of ventricular tachycardia during his admission, an ICD was placed.


Non-ischemic cardiomyopathy secondary to non-compaction of the left ventricle.

Final diagnosis:
Non-ischemic cardiomyopathy secondary to non-compaction of the left ventricle.

Discussion:

Epidemiology
• Prevalence on LVNC in general population is unknown.
• In largest series it has been reported from 0.014% to 0.05%.
• Men are affected more frequently in 56-85% cases.
• Can affect any age group, decribed from 2 ->70 years.

Genetics
• Genetic linkage analysis - mutations in the gene G4.5 (Xq28).
• Genes for cytoskeletal proteins (alpha-dystrobrevin (P121L), Cypher/ZASP.
• Locus on chromosome 11p5 AD LVNC.

Clinical Manifestations
• CHF: systolic and/or diastolic dysfunction – 60 to 82% cases
• Progressive subendocardial ischemia and fibrosis
• Coronary microcirculatory dysfunction – depressed coronary flow reserve in all hypokinetic myocardial segments.
• Abnormal relaxation and restrictive hemodynamics secondary to trabecular network à diastolic dysfunction
• Arrhythmias
• Atrial fibrillation – 25% cases
• Ventricular tachyarrhythmias – 47% cases
• Pediatric population –15% incidence of WPW
• EKG – nonspecific (LVH, repolarization, ST-T, LBBB)
• Thromboembolism (38% cases)
• CVA, TIA
• Related to development of thrombi in the trabeculated ventricle, depressed systolic function or atrial fibrillation.
Diagnosis
• Echocardiogram – Quantitative evaluation determining the ratio on maximal thickness of the non-compacted (NC) to compacted (C), measured at the end systole in parasternal short axis view with a ratio > 2. (See figure A, B, C).

What did we learn from this case?
• Isolated LVNC is an infrequent but not rare cause of cardiomyopathy.
• LVNC presents with more severely depressed ventricular function than other cardiomyopathies.
• LVNC can present clinically in three forms: CHF, arrhythmias or thromboembolism.
• The high morbidity and mortality associated with LVNC should prompt an increased awareness of it for an early diagnosis and treatment.

References:
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Created: 01/21/2008
Updated: 01/22/2008