Abnormal Myocardial Perfusion in a Patient with Left Ventricular Non-compaction

Abstract

Isolated left ventricular non-compaction is a rare congenital cardiomyopathy. Patients frequently present with signs of heart failure and dyspnea on exertion. Myocardial perfusion tests using single photon emission computed tomography are frequently used for evaluation of ischemia. In this case report we present myocardial perfusion images of isolated left ventricular non-compaction from a patient who was referred to our center for evaluation of dyspnea on exertion.

Correspondence
Dmitriy Kireyev, MD, Cambridge Health Alliance, Whidden Memorial Hospital, Cardiology Department, 103 Garland Street, Everett, MA 02149. E: dimonk5@yahoo.com, dkireyev@cha.harvard.edu
Citation
American Heart Hospital Journal 2010;8(2):108-10
DOI
https://doi.org/10.15420/ahhj.2010.8.2.108

A 53-year-old man with a history of paroxysmal atrial fibrillation noticed palpitations two days prior to admission. He complained of dyspnea on exertion over a two-week period. The patient denied orthopnea, paroxysmal nocturnal dyspnea, history of syncope, or lower extremity edema. The patient complained of periodic chest discomfort that was not related to exertion and lasted only a few minutes at a time. He had no risk factors for coronary artery disease and no history of substance abuse. His family history was non-contributory. An electrocardiogram (ECG) on admission showed atrial fibrillation at 95 beats per minute and non-specific ST-segment and T-wave abnormalities. His vital signs were unremarkable. The physical examination was notable for an intermittently irregular rhythm with no murmurs, rubs, or gallops. The initial set of laboratory tests was within normal limits except for borderline elevation of creatinine phosphokinase. A transthoracic echocardiogram was performed (see Figure 1), which showed an ejection fraction of 35%, mild to moderate dilation of all four chambers, mild to moderate reduction in right ventricular contractility, mild aortic regurgitation, moderate mitral valve regurgitation, and mild tricuspid regurgitation. The left ventricular cavity was moderately thickened and had multiple prominent ventricular trabeculations, especially in the mid-portion of the ventricle, consistent with left ventricular non-compaction. Doppler echocardiography showed evidence of blood flow within the intertrabecular recesses connected to the left ventricular cavity. The patient underwent exercise treadmill testing using the Bruce protocol with two-minute stages. Subsequent myocardial perfusion imaging was performed using single photon emission computed tomography (SPECT) with reconstruction into tomographic orientations, polar display, and gated images following the administration of 3.5mCi of thallium-201 at rest and 30mCi of technetium-99m sestamibi at peak exercise. Quality assurance images demonstrated moderate motion during acquisition with a mild male pattern of inferior attenuation.

Image analysis showed a fixed inferior count reduction, which improved with attenuation correction. Endocardial borders were very irregular and prominent mid-ventricular thickening was noticed on the rest images (see Figure 2). Gated SPECT showed global hypokinesis and decreased ejection fraction, consistent with the echocardiogram. A myocardial perfusion comparison between stress and rest scans did not show any evidence of ischemia.

Discussion

Left ventricular non-compaction, sometimes referred to as ‘spongy myocardium,’ is a rare cause of congenital cardiomyopathy. It usually affects the left ventricle, although right ventricular involvement has been described.1 Non-compacted myocardium is most commonly seen in the apical region of the left ventricle.2 It is thought to be caused by early arrest of compaction of myocardial fibers during weeks five to eight of embryonic development.3 Left ventricular non-compaction may present as an isolated finding or may be associated with other congenital abnormalities. Isolated left ventricular non-compaction is usually transmitted in an autosomal dominant pattern; however, X-linked forms have been described.4 There are two layers of myocardium present: a thin compacted myocardium on the epicardial side and a thicker, non-compacted endocardial layer. Multiple prominent myocardial trabeculations with deep intertrabecular recesses with blood flow connected to the left ventricular cavity are diagnostic for this condition. Care should be taken to rule out abnormal blood flow due to anomalous coronary arteries or other abnormalities. Transthoracic echocardiography is commonly used to diagnose left ventricular non-compaction using the criteria described by Chin et al. and Jenni et al.5,6 Magnetic resonance imaging may be used to establish a diagnosis as well.7 Even though multiple gene mutations have been implicated in this condition, no firm relationship between genotype, phenotype, and severity of manifestation has been developed.8

Patients may present with dyspnea, heart failure, palpitations, syncope, transient ischemic attacks, strokes, or arrhythmias.1,2,5 Isolated left ventricular non-compaction carries a poor prognosis: less than 65% of adults survive four years after the development of symptoms.1 The majority of patients who do not receive heart transplantation die from thromboembolic events, ventricular tachycardia, or heart failure.1,5

We present rare images of myocardial perfusion of isolated left ventricular non-compaction. To the best of our knowledge, no such images have been published previously. The mid-ventricular localization of non-compaction is seen in the minority of patients with this condition and makes our case especially interesting. Even though the diagnosis was established by echocardiography, a careful review of the images may have led the nuclear cardiologist to suspect this rare diagnosis based on the nodularity of the wall perfusion and the unusual cavitary appearance of the left ventricle, which is seen especially clearly on the rest images.

References
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