Case report
Spontaneous coronary artery dissection diagnosed by multislice computed tomography

Introduction

Spontaneous coronary artery dissection (SCAD) is a ra­re condition which can lead to acute coronary syndrome and sudden cardiac death [1, 2]. The first case of SCAD was documented in 1931 by Pretty [3] on an autopsy performed on a 42-year-old woman who presented with chest pain, and since then there have been many reported cases. As a result of a series of angiographies, the frequency is reported as 0.28-1.1%. It is presumed that the true incidence is higher, as many cases are diagnosed postmortem. The disease usually occurs in young to middle aged women who are in the peripartum period and present no risk factors of atherosclerosis [1-4]. Coronary artery dissections can occur spontaneously or as a result of coronary angiography, coronary angioplasty, cardiac surgery procedures, blunt chest trauma or enlargement of aorta dissection. The diagnosis of SCAD can be made after elimination of all other causes of coronary artery dissection. The cases with SCAD are divided into three different groups: 1) patients with coronary artery disease, 2) young women in the late pregnancy or early postpartum period, 3) idiopathic group with undetected coronary artery disease risk factors [2, 5, 6]. Diag­- nosis of SCAD is usually made by coronary angiography.

Aim

We describe the case of a patient who came to our clinic with atypical chest pain and was diagnosed with spontaneous coronary artery disease by performing computed tomography coronary angiography, and the diagnosis of SCAD was confirmed by coronary angiography and treated with surgery.

Case report

A 54-year-old female patient referred to our cardiology clinic with recurring chest pain. According to the medical history, she had no complaints of blunt trauma or history of coronary angiography (CAG). She had no risk factors for coronary artery disease. In physical examination, the blood pressure was 110/80 mm Hg and the pulse was 75/min. The electrocardiography (ECG) results and the cardiac enzymes of the patient were normal. A treadmill exercise test was performed by the patient and it turned out to be positive. Computed tomography (CT) angiography was suggested to the patient, who showed a weakly positive treadmill exercise test but had no coronary risk factors. Contrast-enhanced CT coronary angiographic findings were compatible with linear hypodense demarcations which revealed an approximately 3.5 cm dissection line from the proximal left anterior descending artery (LAD) to the second diagonal artery (Figure 1). Therefore coronary angiography was performed and the dissection line was detected in the indicated segment of the LAD (Figure 2). According to the evaluation of the patient, it was decided to perform a coronary artery bypass grafting operation (CABG). The patient was discharged after the CABG with medical therapy.

Discussion

In most cases (70-75%), the clinical presentation of SCAD is sudden cardiac death and it can only be diagnosed in autopsy [17, 18]. The diagnosis of SCAD can be made by coronary angiography among alive patients and the frequency of the disease is indicated as 0.1-1.1% [17, 19]. According to the data, among patients the dissection occurs in 70% of cases in the LAD, 20% in the right coronary artery (RCA), 4% in the circumflex artery (Cx) and in less than 1% in the left main coronary artery (LMCA) [17]. Most of the patients are young to middle aged people who have no risk factors for coronary artery disease. Seventy percent of all cases are women and in 25-30% of these SCAD occurs in the peripartum period.

Spontaneous coronary artery dissection has been defined as dissection of the adventitia from the media of the coronary artery accompanied with or without rupture of the intima, resulting in accumulation of blood in this region in the absence of trauma or iatrogenic causes. As the tunica media dissects, the intimal layer is decompressed into the coronary artery lumen and causes occlusion. The clinical presentation of SCAD depends on the extent and severity of the coronary artery occlusion, and ranging from unstable angina to sudden cardiac death it can present with all types of acute coronary syndromes [16]. The physio­pa­-thology of SCAD remains unclear. Abundant eosinophilic infiltration of the perivascular area is shown in the histopathological examination of the dissection region. Eosinophils release lytic enzymes. It is thought that these enzymes damage the intima and media layer and start the dissection. Another mechanism proposed to explain the underlying mechanism of spontaneous coronary artery dissection is intramedial haemorrhage caused by disruption with bleeding of the vasa vasorum [17, 20]. Causes of SCAD have been observed in three groups of patients: those with coronary atherosclerosis, women in the peripartum period, and an idiopathic group. Oral contraceptives, cocaine abuse, recent chest trauma, Marfan syndrome, cystic medial necrosis, hypersensitivity vasculitis and vigorous exercise have been asso­ciated with SCAD [21, 22].

Coronary angiography is the standard method to diagnose SCAD. Iatrogenic coronary artery dissection occurs in 0.2% of patients who undergo coronary angiography. Existence of a false lumen in angiography is pathognomonic. In coronary angiography, the passage of contrast material between two lumens (true and false lumen) in the media layer distinguished by a thin radiolucent intimal-medial flap is observed. Because contrast material fills the coronary artery wall, the coronary artery lumen can be seen larger. After wash-in of the coronary artery, persistent contrast enhancement may be observed. The compression of the true lumen by the false lumen can simulate stenosis. In the absence of intimal tear, dissection may not be evident. Also, if the true lumen severely narrows, the dissection becomes obscure. Clot filling the false lumen may simulate coronary thrombosis [2, 4]. Intravascular ultrasound is useful especially when the angiographic intimal-medial flap is obscure. It can also be used to differentiate between atherosclerotic coronary artery disease and coronary artery dissection and also to determine the morphology of the dissection [15]. Intravascular ultrasound can be used in the insertion of a guide wire into the true lumen, and evaluation of the diameter of the artery, length of the dissection and the occlusion of the dissection.

As reported in rare cases similar to our case, the diagnosis is made by coronary CT angiography. If used properly, coronary CT angiography can show high sensitivity for diagnosis of SCAD in patients with atypical chest pain, low cardiovascular risk and a weak positive treadmill exercise test. Recently, physicians often use CT angiography among the other tests, and along with coronary occlusion and coronary scoring dissection has to be screened as well. Although coronary angiography is the gold standard in the diagnosis of SCAD, CT angiography may also be considered as an alternative diagnostic method.

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