Long distance of spontaneous coronary artery dissection involving LMT in a middle-aged man — Complete rapid healing and clinical usefulness of CABG as a temporizing strategy

Abstract

Spontaneous coronary artery dissection (SCAD) usually occurs in women, which can result in significant morbidities. A 38 year-old obese man who is currently smoking was referred to our hospital with chest pain. His electrocardiography and echocardiography suggested myocardial infarction in proximal region of left coronary artery. Emergent coronary angiography revealed 99% stenosis at mid portion of LAD and diffuse 50% stenosis from LMT to LAD. Intravascular ultrasound identified intramural hematoma severely compressing the true lumen which extended from mid LAD to LMT suggesting SCAD. After failed fenestration of the false lumen with balloon angioplasty, emergent coronary artery bypass graft using right internal thoracic artery and saphenous vein graft was performed. Two weeks after the surgery, follow-up CAG found completely healed native coronary artery which resulted in occlusion of RITA-LAD graft. This case raises two clinical important issues. First, SCAD can be seen in middle-aged men who are likely to have atherosclerosis. Secondly, CABG is useful as temporizing strategy for unstable SCAD involving LMT. The rapid healing and temporal lifesaving CABG contributed to avoidance of lifelong antiplatelet therapy. Although SCAD is relatively uncommon manifestation of acute coronary syndrome, optimal diagnosis and treatment for each patient need to be considered.

<Learning objective: Spontaneous coronary artery dissection (SCAD) usually occurs in women, which can result in significant morbidities. We experienced an unusual case of SCAD involving LMT in a middle-aged men who are likely to have atherosclerosis. In such a patient who has high risk features, CABG is useful as a temporizing strategy. As spontaneous healing of the native coronary artery can be achieved in a few days, temporizing CABG as a lifesaving treatment is feasible and this make lifelong dual-antiplatelet therapy unnecessary.>

Introduction

Spontaneous coronary artery dissection (SCAD) usually occurs in women and is a relatively uncommon manifestation of acute coronary syndrome (ACS). Although life threatening, optimal treatment for SCAD has not been fully established because of limited number of patients. Here, we experienced a long lesion of SCAD involving LMT in a middle-aged man, which was successfully treated with CABG and the culprit lesion has completely healed in a few weeks.

Case report

A 38 year-old obese man was referred to our hospital with chest pain. Although he smoked one pack of cigarettes per day, he has otherwise no significant medical history. On physical examination, he was slightly anxious but vital signs were generally stable (blood pressure 108/60 mmHg, heart rate 90 b.p.m.). His electrocardiogram showed ST elevation in V1-2 and reciprocal change in limb leads with complete right bundle brunch block (CRBBB). Echocardiography is notable for severe hypokinesis of antero-septal wall and apex region. With regard to chest X-ray and laboratory data, no remarkable findings were noted including troponin I and CK. No other significant coronary risk factors were found except elevated fasting blood sugar level (TG 195 mg/dl, HDL 35 mg/dl, LDL 107 mg/dl, HbA1c 5.3%, FBS 216 mg/dl, respectively). Emergent coronary angiography (CAG) revealed 99% stenosis at mid portion of LAD and diffuse 50% stenosis from LMT to LAD. Intravascular ultrasound (IVUS) identified intramural hematoma severely compressing the true lumen which extended from mid LAD to LMT suggesting the diagnosis of spontaneous coronary artery dissection (Fig. 1). At first we attempted to fenestrate the hematoma with balloon angioplasty, however his hemodynamics gradually worsened. The situation was thought to be hard to be bailed out by catheter intervention, so we proceeded with emergent coronary artery bypass graft (CABG) after insertion of intra-aortic balloon pumping (IABP) and perfusion balloon. Intra operating findings revealed the already improved native coronary artery flow, probably due to the long inflation of perfusion balloon. After anastomosis of left internal thoracic artery (LITA) to LAD, sudden ventricular fibrillation had occurred which was defibrillated with cardioversion. Careful observation identified simultaneous bypass graft dissection which contributed to limited flow of coronary artery. Finally, the new grafts, right internal thoracic artery (RITA) and saphenous vein graft (SVG) were anastomosed with LAD and Diagonal branch, respectively. After the surgery, he recovered well, and follow up CAG 13 days after the surgery revealed nearly healed native coronary artery which resulted in occluded RITA-LAD graft (Fig. 2). 17 days later he was discharged from the hospital and has been followed at outpatient clinic uneventfully for two years.

Fig. 1.

Imaging of Coronary angiography (CAG) and Intravascular ultrasound (IVUS).

A) IVUS of LMT; Thrombosed (★) and non-thrombosed (＊) parts can be identified within the false lumen. No apparent entry of the dissection can be seen.

B) IVUS of LAD/Diagonal branch; Intramural hematoma severely compressing the true lumen.

C) IVUS of distal portion of LAD.

Fig. 2.

Follow-up CAG 13 days after the CABG.

A,B) Completely healed native LAD which resulted in occluded RITA-LAD graft.

C) SVG-Diagonal branch was intact.

Discussion

This patient provided two important clinical issues. First of all, SCAD can occur in middle-aged men who are likely to have atherosclerosis. Recent reviews have reported that the prevalence of SCAD presenting with ACS was 1% to 4% [1] and 90% of these cases were women [2]. While the epidemiology of SCAD in women has been well described, SCAD in men has been rarely reported. Fahmy et al. has recently reported the sex difference in patients with SCAD as both predisposing and precipitating factor [3]. According to the article, men with SCAD were younger, and have less relevance to emotional stress compared with women. On the contrary, as well as women, a high proportion of fibromuscular dysplasia (FMD) was observed in men with SCAD, but not in this case. Although increasing number of recognition and diagnosis have been achieved, optimal diagnosis for the SCAD in atypical epidemiology such as middle-aged men could be misdiagnosed as atherosclerosis related ACS. For optimal diagnosis, intra coronary imaging modalities such as IVUS and OCT should be routinely performed in ACS patients.

Second, CABG is useful as temporizing strategy for unstable SCAD involving LMT. Because SCAD not only can be healed naturally, but also can be life-threatening, the optimal selection of treatment is important. However the management for the SCAD remains undetermined due to the under recognition and lack of randomized trials. Although some data have recommended the conservative therapy on the basis of expert opinions [4], [5], some patients including those with ongoing or recurrent ischemia, hemodynamic instability should be considered for revascularization as in this case. However, our attempt to fenestrate the intramural hematoma with balloon angioplasty [6], [7] unfortunately induced collapsed hemodynamics which required emergent CABG. Recently, Saw has proposed the management algorithm for SCAD [2]. According to this proposal, CABG should be considered in this case from the beginning, since the patient had high-risk features and the lesion involved the LMT and LAD. In this case as well, emergently performed CABG resulted in favorable outcome. Furthermore, this case presented a complete healing of native coronary artery in just 13 days. Long inflation of perfusion balloon and retrograde flow from the graft to native artery might have contributed to this rapid healing mechanism [8]. These findings indicated the clinical usefulness of CABG as a temporizing strategy for unstable SCAD involving LMT. As it can provide coronary blood flow and myocardial perfusion for critically ill patients in whom PCI is unsuitable. Although PCI for LMT requires lifelong dual-antiplatelet therapy, CABG can avoid this. Yet bypass graft patency in SCAD is poor [9], spontaneous healing of the native coronary artery can be achieved in a few days.

Temporizing CABG as a lifesaving treatment is feasible and this make lifelong dual-antiplatelet therapy unnecessary.

Recently, Nakamura et al. reported that the development of SCAD can be related to the both vessel fragility and triggers such as coronary spasm, and SCAD may occur at a certain point due to the summation of vascular fragility and triggers [10]. They described that SCAD triggered by coronary spasm, the onset may depend on the triggers rather than vessel fragility, on the other hand, in a patient with connective tissue such as Marfan syndrome may be more relevant to vessel fragility. In this case, rapid healing of the artery in just a few days might have relevance to triggers rather than vessel fragility, but he has no history of coronary spasm so far. However, further examination such as spasm provocation test would be required.

In conclusion, this case highlighted two clinical issues. SCAD can occur in middle-aged men, and CABG is useful as a temporizing strategy for unstable SCAD involving LMT. Although SCAD is uncommon manifestation of ACS, optimal diagnosis and therapy need to be carefully considered.

Conflict of interest

All of the authors have no conflicts of interest to disclose.