Myocardial Cleft in a Patient with Acute Coronary Syndrome Assessed by Multimodal Imaging.

Myocardial clefts are rare incidental findings without clinical relevance up to now. The recognition of this imaging entity is of crucial importance to avoid misdiagnosis and even more in the context of coronary artery disease.

INTRODUCTION

Myocardial clefts are asymptomatic unusual findings during diagnostic imaging techniques. Up to now, there is no evidence that the identification of myocardial clefts is associated with pathology. Differential diagnosis of this condition is important to avoid a chain of complimentary explorations and aggressive procedures.

CASE REPORT

A 53-year-old man was admitted for unstable angina. He had previous percutaneous revascularization of the left main coronary artery, left circumflex, and right coronary artery. He had medical history of hypertension.

The electrocardiogram on admission did not show signs of ischemia and cardiac troponins were normal.

Vital signs on presentation were normal. His physical findings was not remarkable.

A coronary angiogram showed progression of coronary disease, with two new severe stenoses in the right coronary artery, which were treated with two new drug-eluting stents.

In the ventriculography, a finger-shaped image was observed in the inferior basal segment with contrast penetration [Figures 1a and 2a]. Transthoracic echocardiogram was performed to further characterize this finding. It showed normal LV cavity with mild concentric hypertrophy.

Figure 1

(a) Left ventriculography (right anterior oblique view) showing a left ventricular cleft (white arrow) at the basal inferior wall in diastole. (b) Transthoracic echocardiogram (apical 2-chamber view). Left ventricular cleft (white arrow) in the basal inferior wall in diastole. (c) Transthoracic echocardiogram (apical 2-chamber view). More prominent demonstration of left ventricular cleft (white arrow) with contrast echocardiography in diastole. (d) Cardiac magnetic resonance imaging (left ventricular long-axis view). Myocardial cleft (white arrow) in the basal inferior segment

Figure 2

Left ventricular cleft narrowed in systole in (a) left ventriculography (right anterior oblique view). (b) Transthoracic echocardiogram (apical 2-chamber view) with contrast. (c) Cardiac magnetic resonance imaging (left ventricular long-axis view)

Global LV ejection fraction was normal, and no segmental wall motion abnormalities were identified. A myocardial protrusion was identified in the mid-inferior wall [Figure 1b], corresponding with the ventriculography findings. It was better characterized after Sonovue ® echocardiographic contrast [Figures 1c and 2b], and it was consistent with myocardial cleft. Cardiac magnetic resonance imaging (CMRI) confirmed the diagnosis [Figures 1d and 2c], showing that the cleft was contained by a normally contracting well-perfused myocardium.

DISCUSSION

Clefts (also called “crypts,” “crevices,” or “fissures”) are defined as invaginations penetrating >50% of the thickness of adjoining compact myocardium, perpendicular to the long axis of the LV, tending to narrow [Figure 2] or occlude in systole and without local hypokinesia or dyskinesia.[12]

Congenital LV clefts are usually asymptomatic and discovered incidentally during cross-sectional diagnostic imaging procedures. Alterations in myocardial structure frequently overlooked in the past can nowadays become apparent with the increasing use of multislice computed tomography and CMRI.[34]

The etiopathogenesis of myocardial clefts remains a matter of debate. It is a common belief that they represent a failure to resorb the trabeculated part of ventricular wall during normal embryological development.

Myocardial clefts were initially described in patients with genetic mutations related to hypertrophic cardiomyopathy;[5] however, larger and more recent series with CMRI have found myocardial clefts in 6% of healthy individuals, commonly seen in the interventricular septum and inferior wall of the LV and rarely in apical segments of the septum and ventricular apex.[12] Until now, there is no evidence that the identification of myocardial clefts in healthy population is associated with myocardial disease.

Crypts need to be differentiated from other myocardial wall defects with different pathological profile and clinical significance. It is important to differentiate myocardial clefts from non-compacted myocardium. A non-compacted myocardium is characterized by hypertrabeculated endocardium and a ratio of maximal thickness of the noncompacted to compacted layers of >2 (measured at end-systole in a parasternal short-axis view).[6] It is also necessary to differentiate them from LV diverticulum which is defined as an outpouching structure that extends beyond the anatomic boundaries of LV, and contains endocardium, myocardium, and pericardium.[7]

In our case, in the setting of coronary artery disease, it should be differentiated from aneurysms and pseudoaneurysms. LV pseudoaneurysms form when cardiac rupture is contained by adherent pericardium or scar tissue. Most common causes are myocardial infarction (MI) and surgery. LV aneurysm has a thin, scarred or fibrotic wall, devoid of muscle, or containing necrotic muscle that is a result of a transmural MI.[89]

While clefts are diagnosed with CMRI relatively easily, echocardiographic visualization can be challenging. Although it is not a frequent finding, it is important to recognize it to avoid misdiagnosis that could lead to aggressive procedures.

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Conflicts of interest

There are no conflicts of interest.