Unexpected case of critical left main coronary artery dissection in a young woman

Abstract

A 36-year-old woman presented with a 3-month history of recurrent substernal chest pain, which acutely worsened 2 days prior to presentation. Her initial troponin I was mildly elevated and ECG showed subtle changes initially concerning for ischaemia; however, these were present on her prior ECG and were not considered an acute change. Because of her age and lack of significant risk factors, she was considered low risk for cardiac disease and initially treated conservatively for a non-ST elevation myocardial infarction. Due to persistent symptoms and dynamic changes on ECG concerning for ischaemia, she was immediately taken for a cardiac catheterisation and was found to have critical left main coronary artery dissection with a focal stenotic lesion. She had an extensive workup to identify the underlying cause of her coronary artery dissection which was unrevealing. She underwent an uncomplicated coronary artery bypass graft surgery and was discharged home in stable condition.

Background

Left main coronary artery dissection is a rare occurrence in young women. Most cases of coronary artery dissection in young women are related to spontaneous coronary artery dissection (SCAD), a non-atherosclerotic disease, which has been associated with pregnancy, physical and emotional stressors, underlying connective tissue disorders or systemic arteriopathies, particularly fibromuscular dysplasia.¹ We share with the reader a case of a young woman with an unexpected cause of critical left main coronary artery (LMCA) dissection.

Case presentation

A 36-year-old non-smoking, obese Bangladeshi woman with hypothyroidism, chronic migraines and prior gestational diabetes mellitus presented to the emergency department with a 2-day history of substernal and progressively worsening chest pain. The pain was described as 10/10 in severity, pressure-like, exertional, radiating to bilateral upper extremities and associated with multiple episodes of non-bloody, non-bilious emesis, shortness of breath and diaphoresis. She denied any weight loss, constitutional symptoms, upper respiratory symptoms, neurological symptoms or skin changes. She reported similar episodes that occurred in the past 3 months, but previously the pain would only last 5–10 min and resolve spontaneously hence, she never sought out medical evaluation. She denied any recent physical or emotional stressors, history of blunt chest trauma or strenuous exercise. There was no family history of heart disease or hypercholesterolaemia. She denied use of alcohol or illicit drugs. Her temperature was 97.9°F with a heart rate of 124 beats/min, respiratory rate of 23 breaths/min, blood pressure of 165/99 mm Hg and oxygen saturation of 100% on room air.

She was tachycardic, with normal S1 and S2 heart sounds, and no murmurs or chest wall tenderness were appreciated. Pertinent laboratory findings included a white cell count of 15.2×10⁹/L, haemoglobin of 10.3 g/dL, lactic acid of 2.47 mmol/L and negative urine pregnancy test. Urine toxicology screen testing for cocaine, barbiturates, amphetamines and cannabinoids was negative. Her urine was positive for opiates and benzodiazepines, which was suspected to be due to medications given to her in the emergency department. As stated above, she denied any history of illicit drug use. Her lipid profile showed triglycerides of 131 mg/dL, total cholesterol of 106 mg/dL, low-density lipoprotein of 48 mg/dL and high-density lipoprotein of 32 mg/dL. Her coagulation markers including prothrombin time (PT), international normalised ratio, activated partial thromboplastin time (aPTT), fibrinogen and d-dimer were all within the normal reference values. She also had a workup for the presence of lupus anticoagulant (LA) which was not detected based on normal LA-sensitive PT, aPTT, thrombin time, silica clot time and dilute Russell Viper Venom test. She had a negative autoimmune workup consisting of negative antinuclear antibody (Ab) screen, rheumatoid factor, p-ANCA, c-ANCA, Jo-1 Ab, SSA-Ro Ab, SSB-La Ab, anti-smith Ab, anti-RNP Ab and anticardiolipin antibodies. Her initial troponin I was 1.78 ng/mL and her ECG on admission showed sinus tachycardia, right atrial enlargement, abnormal progression of R waves in V1–V3 and T-wave inversions in the septal leads (figure 1). There was also minimal ST depression in leads I and aVL, an increase in T wave amplitude in leads III and aVF, and ST elevation in aVR. The T-wave inversions and ST elevation in aVR were initially concerning for ischaemia; however, when her ECG was compared with her ECG from a few years prior, these findings were present at that time and appeared unchanged. We calculated the thrombolysis in myocardial infarction (TIMI) risk score: 3 (low risk). Because of her low TIMI risk and lack of significant ECG changes when compared with her prior ECG, she was treated medically for a non-ST elevation myocardial infarction (MI). Her chest pain began to improve until 3 hours later when she began to experience another episode of chest pain. An ECG was immediately performed which showed sinus tachycardia and ST-depressions in the anterior, inferior and lateral leads (figure 2).

Figure 1.

Initial ECG on admission showing sinus tachycardia, right atrial enlargement, abnormal progression of R waves in leads V1–V3 and T-wave inversions in the septal leads. There is also minimal ST depression in leads I and aVL, an increase in T wave amplitude in leads III and aVF and ST elevation in aVR.

Figure 2.

ECG repeated 3 hours later showing sinus tachycardia with ST depressions in anterior, inferior and lateral leads.

Treatment

Due to the dynamic changes noted on her ECG and persistent chest pain, she underwent emergent cardiac catheterisation. She was found to have critical dissection of the LMCA with 90%–95% lumen stenosis (video 1). Her left circumflex (LCx), left anterior descending (LAD) and right coronary artery did not show any abnormalities. Due to the location of the lesion, LMCA was not selectively intubated and intravascular ultrasound (IVUS) was deemed unsafe to perform. No procedural-related coronary dissection was reported by the operator. An intra-aortic balloon pump was placed as a bridge to urgent coronary artery bypass graft (CABG) surgery and removed 24 hours later due to threatening acute limb ischaemia.

Video 1.

Download video file ^{(265.2KB, mp4)}

DOI: 10.1136/bcr-2020-236379.video01

Because the lesion was in the LMCA which bifurcates into the LAD and LCx, thereby affecting the blood supply to both, she underwent an uncomplicated CABG with two conduits: left internal mammary artery to LAD artery and saphenous vein graft to the obtuse marginal artery. She had an uneventful postoperative recovery and was discharged home in stable condition a few days later.

Outcome and follow-up

She had an uneventful postoperative recovery and was discharged home in stable condition a few days later. At 3 months post CABG surgery, the patient was able to resume her usual activities with minimal discomfort.

Discussion

LMCA dissection with underlying atherosclerotic disease, especially in a young healthy woman, is a rare occurrence.² A condition known as SCAD which is considered to be a non-atherosclerotic disease, is more commonly seen in this population. Our case highlights the unique presentation of coronary artery dissection in the setting of focal stenotic lesion in a young patient.

Atherosclerosis is traditionally described as a disease of ageing and it has been shown that increasing age is an independent risk factor for the development of atherosclerosis.³ There are multiple systemic factors that contribute to vascular ageing and development of atherosclerosis including genetic predisposition, cellular senescence and acquired risk factors like smoking, chronic high alcohol intake and diabetes mellitus.³ There are also known differences in the incidence of atherosclerotic disease in individuals based on racial and ethnic groups. South Asians originating from India, Pakistan, Bangladesh, Sri Lanka and Nepal are known to have a higher risk of cardiovascular disease attributed largely to a poor diet compared with the general population.⁴

In the case presented above, the patient’s medical conditions included obesity, chronic migraines and hypothyroidism. Despite not having other traditional cardiac risk factors that are more commonly seen in patients that present with acute coronary syndrome (ACS), she was still at a higher risk than the general healthy population to developing atherosclerotic heart disease due to her risk factors and ethnic background (Bangladeshi), despite her young age.

There are multiple scoring methods to risk stratify patients presenting with chest pain. The PURSUIT (Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrellin Therapy), TIMI (Thrombolysis in Myocardial Infarction), GRACE (Global Registry of Acute Coronary Events), FRISC (Fast Revascularization in Instability in Coronary disease) and HEART (Heart, ECG, Age, Risk factors and Troponin) scores are well validated and commonly used to guide therapy for patients based on whether they are low, intermediate or high risk for ACS.⁵ Majority of these scores have higher age cut-offs and are designed for risk stratifying an older population of patients. In the case presented above, the TIMI risk score was used for risk stratification. Due to a low risk of ACS according to the TIMI score, the patient did not undergo immediate cardiac catheterisation. In retrospect, because these scores have not been validated in a younger age group,⁵ our misuse of this risk stratification tool incorrectly guided our initial management of this patient. These scores have also not been validated in the South Asian population and may underestimate cardiovascular risk.⁶ It is also important to note that there should be a high level of alertness, especially if subtle ECG changes are noted as in our patient’s initial ECG (figure 1).

The common manifestation of SCAD is ACS with ST-segment changes in half of the patients.⁷ It is usually associated with fibromuscular dysplasia with a reported prevalence of 35%–86% in cohort studies.¹ As stated earlier, associated risk factors include pregnancy, physical/emotional stressors, exogenous hormones, underlying connective tissue disorders or systemic inflammatory diseases.⁸ Chronic migraines have also been linked to SCAD in young women.⁹ Our patient had prior hospital admissions for chronic temporal migraines.

A complete workup was done on our patient including extensive history taking to identify any possibility of systemic arteriopathies and labs to exclude autoimmune or hypercoagulable diseases which were all negative. She was not screened for thrombophilia as she had already received anticoagulants which could have potentially affected the test result.

Diagnosis of SCAD is typically performed by invasive coronary angiography and IVUS. By the use of IVUS, it was found that a majority of SCAD cases do not demonstrate the typical double lumen pattern on angiography.¹⁰ As a result, a specific classification for diagnosis of SCAD by angiography was created to differentiate it from iatrogenic dissections: type 1 lesions are defined by the presence of a double lumen, type 2 lesions are defined by luminal narrowing, with a lesion length >20 mm and lastly, type 3 lesions are defined by an abrupt lumen narrowing with distal vessel size recovering that limits a focal lesion (length <20 mm), mimicking an atherosclerotic lesion.¹⁰ With our patient’s presentation and coronary catheterisation findings (video 1), we can infer that a type 3 coronary artery dissection was the precursor for her ACS.

The optimal management of SCAD is not yet established due to the rare nature of the condition and limited clinical experience of providers. Although the preferred management of SCAD in patients is conservative therapy, it usually depends on the clinical presentation of the patient and suspected underlying cause. When patients are managed conservatively, they are treated with long-term aspirin, a beta blocker, clopidogrel for 1 year and a statin if patients have dyslipidaemia or risk factors for atherosclerotic disease.^{11 12} Patients that present with an acute MI, symptoms of ongoing ischaemia, haemodynamic instability or LMCA dissection are considered for urgent revascularisation with percutaneous intervention (PCI) or CABG.^{1 11} PCI is a challenging treatment option, particularly because the dissection contributes to fragility of the vessel wall. Any instrumentation of the vasculature can lead to serious complications including worsening dissection, occlusion of side branches, rupture of the blood vessel wall or death. As a result, revascularisation in patients with SCAD is associated with higher rates of complications and technical failure when compared with conservative therapy.^{13 14} Although the patient presented in the case had a focal stenotic lesion with no further coronary circulation involvement, due to the location of the lesion and potential complications of PCI, the decision was made to perform emergent CABG.

Patient’s perspective.

It’s very tough for someone young like me to be told they have heart disease. When I was having pain in my chest on and off for many months, I thought maybe it was related to the food I was eating. I thought I had heartburn, but never did I think I could have a problem with my heart. It was only when the pain became unbearable that I thought to myself, maybe this is something more serious. I’m glad my husband brought me to the hospital that day because the doctors told me if I waited too long it may have been too late.

Nobody in my family has heart problems so I was surprised when they told me I did. It was a hard decision to have bypass surgery because I had never heard of that before. Usually I hear older people have heart bypass surgery. I didn’t really have many options because of my condition, but thankfully the surgery went well. The few months after surgery were difficult but I recovered and don’t have chest pain like I did before. Now I can spend time and be active with my kids without worrying.

Learning points.

• Most cases of coronary artery dissection in young patients are due to non-atherosclerotic conditions including pregnancy, physical or emotional stressors, connective tissue diseases or arteriopathies.

• Angiographic features of coronary dissection are diverse and can mimic other conditions.

• Mortality of this condition is very high.

• Risk stratification tools are useful, however, do not apply to all patient populations, a high index of clinical suspicion should guide your management.

• Timely recognition and diagnosis of this condition can allow for rapid intervention and improved patient outcomes.