Simultaneous occurrence of spontaneous coronary artery dissections of the left anterior descending and right coronary arteries in acute myocardial infarction

Abstract

Spontaneous coronary artery dissection (SCAD) is a rare and often fatal cause of ischemic heart disease that occurs predominantly in young or middle-aged patients who are otherwise healthy. Therefore, the accurate diagnosis of SCAD and initiation of appropriate treatment may be life-saving. Although recent case reports have described patients with SCAD who exhibited multiple coronary dissections in addition to the culprit lesion, the authors could not determine whether the multiple dissections occurred simultaneously or at different times. In this report, we describe a case involving the simultaneous occurrence of multiple SCADs in the right coronary artery and left anterior descending artery. Intravascular ultrasound helped us to confirm the diagnosis of multiple SCADs, confirm their simultaneous occurrence, and navigate the guidewire into the true lumen.

<Learning objective: In general, spontaneous coronary artery dissection (SCAD) is a single-vessel disease; the left anterior descending artery is the vessel most often involved, followed by the right coronary artery. However, the possibility of other coronary dissections distant from the culprit lesion should be considered in patients who present with an acute coronary syndrome due to SCAD. A prompt diagnosis and patient-tailored management can reduce morbidity and mortality in this population.>

Introduction

Spontaneous coronary artery dissection (SCAD) is a rare phenomenon, and it sometimes results in acute coronary syndrome and sudden cardiac death [1], [2], [3]. Although SCAD was previously thought to be a single-vessel disease, some cases involving dissections in multiple vessels have been reported [4], [5], [6]. However, it has not been clarified whether the multiple SCADs occurred simultaneously or independently.

We report on a case that involved the simultaneous occurrence of SCADs in the right coronary artery (RCA) and left anterior descending coronary artery (LAD) of a woman who presented with an acute myocardial infarction.

Case report

A 38-year-old woman presented with an acute myocardial infarction. She suddenly experienced severe anterior chest pain at rest, and walked to the nearest hospital. Her initial electrocardiogram (ECG) revealed 0.3 mV ST-segment elevation in the anteroseptal leads (V2–5) (Fig. 1A). Given her symptoms and ECG findings, the presumptive diagnosis was an acute anterior ST-elevation myocardial infarction (STEMI), and she was transferred to our hospital. She was not pregnant, and did not have risk factors for coronary atherosclerosis. There was no family history of sudden death, and no history of connective tissue disease, drug abuse, or recent trauma. After she was transferred to the emergency room of our hospital by ambulance, her repeat ECG on arrival was completely different from the ECG obtained at the previous hospital. The ECG at our hospital revealed 0.2 mV ST-segment elevation in the inferior leads II, III, and aVF, and complete resolution of the ST-segment changes in the anteroseptal leads (Fig. 1B). No elevation in her serum creatine kinase was detected in her admission blood sampling. Based on the findings of her second ECG, we suspected she was having an acute inferior STEMI, and she was referred for cardiac catheterization. The coronary angiography revealed a severe stenosis at the ostium of the RCA, and the presence of a thin longitudinal radiolucent line, representing an intimal medial flap with contrast staining (Fig. 2A). Her left circumflex coronary artery was smooth walled with no evidence of atherosclerosis, however, a mild stenosis was observed in the middle LAD (Fig. 2B). We then performed an intravascular ultrasound (IVUS) to assess the etiology of the arterial narrowing in the ostial RCA. The lesion was crossed with a 0.014-inch guidewire (SION Blue, Asahi Intec Co. Ltd., Aichi, Japan), which was steered into the distal-RCA with angiographic guidance. Subsequently, a 40 MHz IVUS catheter (ViewIt, Terumo Corp., Tokyo, Japan) was advanced into the RCA, and pulled back automatically at a speed of 1.0 mm/s up to the guiding catheter. The IVUS revealed an extensive circumferential dissection, with a mobile intimal flap that extended deep into the media layer at the culprit site, suggesting a SCAD (Fig. 3A–D). There was no evidence of atherosclerotic changes on the IVUS. Although we attempted repeated balloon dilations using a 3.0-mm coronary balloon with long inflation, there was a marked recoil of the lesion following balloon dilation. Therefore, a 3.5 mm × 23 mm drug-eluting stent (Xience Alpine, Abbott Vascular, Tokyo, Japan) was deployed to cover the entire dissection; the final IVUS examination demonstrated sealing of the dissection with good stent apposition. Another IVUS examination was performed to elucidate the cause of the mild luminal narrowing in the middle LAD. The IVUS demonstrated a medial dissection with an intramural hematoma that started at the middle segment of LAD and extended into the distal segment of LAD; there was no evidence of atherosclerosis (Fig. 3E and F). The patient's chest pain symptoms disappeared completely and the ST-segment elevations on the ECG resolved after the intervention, and she was discharged on aspirin and clopidogrel. She is currently asymptomatic and is scheduled for a repeat coronary angiogram 8 months after the intervention.

Fig. 1.

Initial electrocardiogram (ECG) at presentation revealing ST-segment elevation in the anteroseptal leads (A). Second ECG 30 min after the initial ECG showing the complete resolution of the initial changes and ST-segment elevation in the inferior leads (B).

Fig. 2.

Left anterior oblique projection showing a flap-like filling defect in the proximal right coronary artery (A). A diffuse, confined lesion in the mid left anterior descending artery (arrows) (note normal proximal and distal segments) is identified (B).

Fig. 3.

Intravascular ultrasound (IVUS) showing a dissection and intramural hematoma that starts at the proximal right coronary artery and progresses. An intramural hematoma in the medial layer of the arterial wall is compressing the true lumen (A). A schema of A (B). The intima is torn off together with the medial part (asterisks) (C). A schema of C (D). IVUS examination revealing a hematoma (asterisk) compressing the true lumen (E). A schema of E (F).

Discussion

In this case, the IVUS allowed us to: (a) confirm the diagnosis of the SCADs, (b) confirm the simultaneous occurrence of the SCADs, (c) detect the guidewire into the true lumen, and (d) choose optimal stent and balloon size.

SCAD is a rare disease characterized by a deep coronary dissection which usually occurs in the outer media, or between the media and adventitia [7]. The typical clinical features are consistent with an acute coronary syndrome in a patient who has a low probability of atherosclerotic disease. A previous study reported that SCAD accounts for only 0.2–0.3% of acute coronary syndromes in the general population [8]. SCAD has been described in young women during the peripartum period and in women using oral contraceptive pills [1]. The histopathology of SCAD shows a dissection plane between the media and the adventitia of the coronary artery, due to cystic medial necrosis or hemorrhagic disruption of the vasa vasorum [9]. Cystic medial necrosis usually involves focal fragmentation and the loss of smooth muscle cells and elastic fibers of the media, associated with deposits of varying amounts of acid mucopolysaccharides. The recent development of IVUS imaging has allowed clinicians to accurately diagnose SCAD in suspicious cases, and to date more than 500 cases have been reported in the medical literature, diagnosed by angiogram, IVUS, or optical coherence tomography. In most of these cases, the SCAD occurred in a single-vessel disease; the LAD is the vessel most often involved, followed by the RCA, the left main, and circumflex artery [3]. On the other hand, reports have demonstrated that multiple SCADs have been found distant from the culprit lesion in patients who presented with acute coronary syndromes [4], [5], [6]. However, it was not clear whether the multiple dissections occurred simultaneously, or on separate occasions. In this case, the patient's initial ECG at the previous hospital demonstrated ST-segment elevation in the anteroseptal leads, however the ECG taken 30 min later at our hospital revealed ST-segment elevation in the inferior leads. Therefore, we speculated that these two dissections occurred simultaneously in this patient. Hormonal changes in peripartum women or women taking oral contraceptive pill may decrease mucopolysaccharides and elastic fibers, and cause the fragmentation of reticulin fibers [10]. In addition, eosinophil infiltration into the media of the coronary arteries may injure the vascular wall; their degranulation can lead to the injury of collagenous elastic fibers or vascular smooth muscle cells. Coupled with changes in blood flow that increase shear stress, these conditions can cause pan coronary instability and may predispose a patient to SCAD not only in one artery or one part of the artery, but in all their coronary arteries. She had to take care of two children without support from her husband, because her husband was away on business. Therefore, at the time of presentation, the patient had been under significant stress for about 3 days, which may have caused hemodynamic disturbance, for example increased afterload, contributing to the occurrence of multiple SCAD in some way without the background of hypertension. Another potential cause of this SCAD could be the presence of underlying vascular disorder such as fibromuscular dysplasia, which has been observed in up to 70–90% of SCAD patients [11], although no coronary aneurysm or ectasia was found on coronary angiography. The other possible cause of SCAD including connective tissue disorders, systematic inflammatory diseases, and hormonal therapies was ruled out for this patient. To the best of our knowledge, this is the first case report of simultaneously occurring SCADs confirmed by IVUS in a patient with an acute coronary syndrome. Careful interpretation of coronary angiography is crucial to avoid the misdiagnosis or underdiagnosis of a concealed SCAD, in addition to the culprit artery lesion, in patients with acute coronary syndrome.

The treatment strategy for SCAD, balloon angioplasty, bare-metal stent or drug-eluting stent, should be carefully discussed. Although the technique of percutaneous coronary intervention is promising, long-term outcome and complication rates have not been clarified.

Conflict of interest

The authors declare that there is no conflict of interest.