Recurrent acute coronary syndrome in a patient with spontaneous coronary artery dissection and fibromuscular dysplasia

Abstract

A 51-year-old woman who presented in June 2010 with acute coronary syndrome (ACS) and anterior wall motion abnormality on the echocardiogram but was found to have an insignificant angiogram. Eight years later she presented again with ACS and evidence of worsening cardiac wall motion affecting a similar territory; however, the angiogram revealing spontaneous coronary artery dissection of the distal left anterior descending artery. Extravascular screening revealed evidence of multifocal fibromuscular dysplasia. We suggest offering vascular screening for fibromuscular dysplasia in young women who present with ACS and normal angiograms, after weighing in risks and benefits.

Background

Spontaneous coronary artery dissection (SCAD) is defined as epicardial coronary artery dissection which is not presumed to be atherosclerotic, traumatic or iatrogenic in aetiology.¹ It leads to myocardial injury, secondary to coronary artery obstruction by the formation of an intramural haematoma or intimal disruption. Despite recent advances, it still remains a diagnostic challenge and often gets misdiagnosed.² It is most prevalent in younger patients, particularly women with few conventional atherosclerotic risk factors. It is commonly associated with predisposing arteriopathy, fibromuscular dysplasia (FMD) is found in around 70% of cases.

Case presentation

A 51-year-old woman with a history of dilated cardiomyopathy diagnosed in February 2009 with a left ventricular ejection fraction (EF) of 15%, new onset left bundle branch block (LBBB), elevated C reactive protein, mild elevation of alanine aminotransferase and aspartate aminotransferase, normal cardiac enzymes and insignificant coronary angiogram. Several months prior to the diagnosis, the patient had symptoms of shortness of breath, fatigue, intermittent fevers, with elevated white blood cell count on laboratory work-up. The symptoms worsened with associated orthopnea requiring a cardiac evaluation. Three months after the diagnosis, the patient was on guideline-directed medical therapy with minimal symptomatic improvement requiring cardiac resynchronisation therapy. Her medical history included cocaine use in her 20s, last pregnancy 3 years prior with no symptoms post partum and no alcohol use.

Over the next few months, her EF normalised with cardiac resynchronisation therapy. She presented in June 2010 to our hospital with chest pain, elevated cardiac enzymes and ST-T changes in lateral leads. Transthoracic echocardiogram (TTE) revealed left ventricle (LV) mid-anterior and distal anterior and inferoapical hypokinesis with an EF of 40%; nuclear stress test was significant for an anterior apical scar with an EF of 30% and a subsequent angiogram showed no obvious coronary artery disease but akinetic anterolateral wall (figure 1).

Figure 1.

Coronary angiography showing normal coronary arteries with no obvious abnormality in June 2010.

The patient was closely followed up and in 2013, she presented with occasional episodes of chest heaviness to the office and was found to have paced QRS with a small fixed apical scar on nuclear stress test and an EF of 55%.

The patient now presented 8 years later at the emergency department with substernal chest pain at rest for 1 day. Systemic examination did not reveal any significant findings. The patient was vitally stable.

Investigations

ECG showed an LBBB and troponin T was trending up. TTE was significant for severe hypokinetic anterior and inferoseptal LV wall with an EF of 27%. Left heart catheterisation showed no atherosclerotic coronary artery disease but an abrupt irregular narrowing in the distal left anterior descending artery (LAD) which was diffuse and occluded approximately 60% of the arterial lumen with the reconstitution of the normal lumen in the apical segment. Intracoronary nitroglycerin was used with no response, highly suggestive of a type 2 SCAD of the mid-distal LAD (figure 2).

Figure 2.

Coronary angiography showing type 2 spontaneous coronary artery dissection (SCAD) of distal left anterior descending artery (LAD).

The patient was managed medically and given concern for SCAD, the patient underwent vascular imaging that showed multifocal FMD in the right external iliac, left internal carotid (figure 3) and vertebral arteries.

Figure 3.

CTscan of the neck in sagittal view showing fibomuscular dysplasia in left internal carotid artery (LICA).

The patient was started on dual antiplatelet therapy and was referred to cardiac rehabilitation. In a nutshell, we presume recurrent undiagnosed SCAD events as the underlying aetiology of her cardiomyopathy and recurrent anginal presentations, as the culprit vessel was the same 9 years ago.

Treatment

The patient was started on dual antiplatelet therapy for a total duration of 1 year and was referred to cardiac rehabilitation.

Outcome and follow-up

The patient successfully completed all the sessions of cardiac rehabilitation and remained asymptomatic afterwards. In a nutshell, we presume recurrent undiagnosed SCAD events as the underlying aetiology of her cardiomyopathy and recurrent anginal presentations, as the culprit vessel was the same 9 years ago.

Discussion

First recognised in 1931 by Pretty at autopsy and thought of as a rare cause of acute coronary syndrome (ACS) and sudden cardiac death in the peripartum period, recent advances in our understanding of the epidemiology of SCAD, availability of intravascular imaging techniques, the development of SCAD-specific angiographic classification and heightened awareness among the providers as well as patients suggest that SCAD is far more common than initially thought of, especially in young women.¹ However, it still remains undiagnosed, misdiagnosed and managed as atherosclerotic ACS, hence its true prevalence remains uncertain.³ The underlying pathology involves the development of a spontaneous disruption in the vessel wall (intimal tear), which allows blood from the true lumen to enter and generate a false lumen or a spontaneous haemorrhagic event in the vasa vasorum of the vessel wall with resultant haematoma formation and intraluminal compression.^{4 5}

Coronary angiography is the recommended first-line diagnostic imaging modality for SCAD. LAD and its branches are the most common sites affected. SCAD manifests as three main angiographic features. Type 1 has multiple radiolucent lumens or arterial wall straining, Type 2 is diffuse vessel wall stenosis, with normal arterial segments subclassified as 2A, and diffuse narrowing from proximal/midsegments to the distal artery characterised as type 2B. Type 3 is focal or tubular stenosis, it is commonly confused as atherosclerotic artery disease.⁶ Our patient had type 2B SCAD.

SCAD is commonly associated with predisposing arteriopathy, FMD found in around 70% of cases.² FMD is a non-atherosclerotic, non-inflammatory vascular disease that can affect any arterial bed and manifests as arterial stenosis, aneurysm, tortuosity or dissection. Multifocal FMD is the most common FMD and is defined angiographically as areas of alternating stenosis and dilation in a string-of-beads pattern, whereas focal FMD appears angiographically as a single concentric or tubular narrowing, and constituted 10% of FMD.⁷ It is recommended to exclude FMD in all cases of SCAD as the involvement of other vascular territories has long-term consequences. A complete vascular physical examination with diminished or asymmetrical pulses or audible bruit is the initial step (low sensitivity but high specificity). Expert consensus recommends consideration of vascular imaging from the brain to pelvis in all patients with SCAD with the ultimate goal to detect high-risk aneurysms or extracoronary abnormalities requiring prompt intervention.⁸ Patient counselling regarding possible outcomes including risk of further testing, false reassurances and the anxiety of knowledge of harbouring an aneurysm or dissection with or without intervention, as well as an explanation of the risks of radiation exposure with multiple tests and its teratogenic potential, is of paramount importance.^{9 10}

Despite a surge in diagnosis in the past decade, SCAD still remains undiagnosed. Gender and age bias leads to a low index of suspicion among healthcare providers. In two retrospective studies of patients with angiographically confirmed SCAD, the mean age of women were 43 and 52 years.^{3 11} In a landmark study reported in the New England Journal of Medicine, researchers found that women under the age of 55 who experienced ACS-type symptoms were seven times more likely to be misdiagnosed and discharged from the emergency department as compared with their male counterparts.¹²

Patient counselling regarding possible outcomes including the risk of further testing, false reassurances and the anxiety of knowledge of harbouring an aneurysm or dissection with or without intervention, as well as an explanation of the risks of radiation exposure with multiple tests and its teratogenic potential, is of paramount importance.

Patient’s perspective.

I am very much engaged and interested in research, especially the problems which I am suffering from, so that they don’t impact my daughters as well as other human beings of the world in the future and would be a source of help for them.

Learning points.

• Spontaneous coronary artery dissection (SCAD) is defined as epicardial coronary artery dissection which is not presumed to be atherosclerotic, traumatic or iatrogenic in aetiology.

• Spontaneous coronary artery dissection is an infrequent cause of acute coronary syndrome (ACS) and a high index of suspicion should be kept in mind in young and middle-aged women.

• SCAD still remains underdiagnosed despite heightened awareness among patients as well as healthcare providers.

• Although no guidelines exist, in young women who have recurrent presentations of an ACS with minimal risk factors and normal coronary angiograms, we suggest work-up for fibromuscular dysplasia, as spontaneous coronary artery dissection still remains underdiagnosed.