Rare case of asymptomatic spontaneous coronary artery dissection

Abstract

We present a case of a 46-year-old woman who presented to the emergency room after a syncopal episode. Most of her initial workup did not lead to any diagnosis. However, the transthoracic echocardiogram showed new onset left ventricular dysfunction. Further, cardiac evaluation showed a chronic coronary artery dissection in the proximal left anterior descending artery. Syncope was related to vasovagal event but rapid plasma reagin being positive led to the question of whether the coronary artery dissection was secondary to vasculitic manifestation of prior syphilis infection. More research is needed to answer this question and to find such an association.

<Learning objective: Spontaneous coronary artery dissection (SCAD) is a rare disease of young adults that can present acutely as an acute coronary syndrome (ACS) with chest pain, as malignant ventricular arrhythmia, and even as sudden cardiac death. Our report is focused on evaluation and management of SCAD, more importantly to consider SCAD as a differential diagnosis in ACS in young patients, especially females. Our review also stresses the need for further research toward development of consensus on management of such patients.>

Introduction

Spontaneous coronary artery dissection (SCAD) is characterized by the presence of blood or thrombus, in false lumen, usually in the outer third of vessel wall [1]. This false lumen extends for a variable distance down coronary artery and can obstruct blood flow to a variable extent within true lumen, causing ischemia or infarction of the myocardium. Overall, left anterior descending coronary artery (LAD) is the most commonly involved coronary artery [2]. Right coronary artery SCAD is more common in males whereas left coronary circulation SCAD is more common in females [2]. It may present acutely as myocardial ischemia with chest pain, acute coronary syndromes (ACS), and malignant ventricular arrhythmia. We report a case of rare asymptomatic SCAD presenting as late ischemic cardiomyopathy.

Case report

A 46-year-old woman was brought to our hospital by Emergency Medical Services (EMS) after a syncopal episode and injury to her head while at a grocery store. Prior to the event, she reported lightheadedness and blurry vision but denied any palpitations, dyspnea, nausea, or vomiting. She reported losing consciousness for about 1–2 min and being lucid upon regaining consciousness. She also gave history of vague chest discomfort, which resolved on its own after she woke up. She denied similar symptoms in the past. Her medical history was significant for bronchial asthma, syphilis treated 18 years previously, and psoriasis. Her medications included iron supplements, montelukast, and salmeterol-fluticasone inhaler. There was no significant history of coronary artery disease or any other illness in the family. She denied smoking tobacco, drinking alcohol, or illicit drug use.

In the emergency room, she was hemodynamically stable and her physical examination was within normal limits. Electrocardiogram (ECG) showed her to be in normal sinus rhythm, with left-axis deviation and anteroseptal Q-waves with T wave inversions (Fig. 1). No prior ECG was available for comparison. Chest roentgenogram showed prominent pulmonary vasculature with cardiomegaly. Subsequently, she was admitted for further workup and management for syncope. Her cardiac markers were negative throughout the hospital stay. Telemetric monitoring was unremarkable. Echocardiogram showed regional wall motion abnormalities (anteroseptal and anterior akinesis), apical aneurysm, and severely reduced left ventricular ejection fraction (LVEF). In view of echocardiographical findings, she underwent coronary angiography which showed proximal left anterior descending artery (LAD) dissection with Thrombolysis in Myocardial Infarction (TIMI) angiographic flow grade III (Fig. 2). All other coronaries were patent with TIMI III flow. Intravascular ultrasound (IVUS) during the angiography confirmed a chronic complex dissection with false lumen, 15 mm in length in the proximal LAD (Fig. 3). The LAD territory was nonviable on myocardial perfusion imaging (MPI) (Fig. 4). On further testing she was diagnosed with tertiary syphilis (positive rapid plasma reagin titer of 1:4 with a positive fluorescent treponemal antibody absorption test) without central nervous system involvement (negative cerebrospinal fluid analysis). She had an elevated erythrocyte sedimentation rate of 102 mm/h and a negative C-reactive protein assay. After complete workup, syncope was attributed to vasovagal reflex based on a suggestive history. She was started on treatment for tertiary syphilis and managed with carvedilol, aspirin, simvastatin, and lisinopril for congestive heart failure. She was prescribed life vest upon discharge with a plan for automated implantable cardioverter-defibrillator placement as an outpatient for primary prevention of sudden cardiac death.

Fig. 1.

Electrocardiogram showing normal sinus rhythm, left axis deviation, and anteroseptal Q-waves with T wave inversions.

Fig. 2.

Right anterior oblique cranial view (A) and left anterior oblique caudal view of left anterior descending artery showing dissection in proximal part (arrow).

Fig. 3.

Section of left anterior descending artery on intravascular ultrasound showing intimal flap (arrow) and false lumen (star).

Fig. 4.

Myocardial perfusion imaging showing a fixed defect from apex to base of the anteroseptal wall.

Discussion

SCAD is a rare cause of ACS predominantly affecting the young population. Its incidence varies from 0.07% to 1.1% among patients undergoing coronary angiography [3]. Clinically, it presents with chest pain, malignant ventricular arrhythmia, sudden death, or ACS because of acute ischemia [1], [2], [4].

Tweet et al. have reported characteristics, outcome, and management in one of the largest cohort of patients with SCAD. Eighty-seven consecutive patients were included in the report. The mean age was 42.6 years and 83% of the cohort were females. All patients in the series had presented with chest pain and/or ventricular arrhythmias [4]. Similarly, data from the Western Danish registry showed that the mean age for SCAD was around 48 ± 8.9 years, with a female preponderance (77%) and ACS was the most common presentation [2]. More recent analysis by Saw et al. showed the incidence of non-atherosclerotic SCAD being more common in older women, which is contrary to the belief that it mostly affects young women. Around 58% of all females in the study were older than 50 years [5].

Extreme exertion and peri-partum period are the most common predisposing factors in males (44%) and females (18%), respectively for SCAD, but it is rarely seen in elderly women with no coronary risk factors or cardiovascular disease. Other predisposing conditions include cocaine use, fibromuscular dysplasia (50% of patients), Elher-Danlos Syndrome, fibrillin gene variants, hormonal therapy, polycystic kidney disease, atherosclerosis, and chronic inflammation. However, in many cases no predisposing condition is found [2], [3], [4], [6].

The exact pathogenesis of SCAD is unclear. Autopsy series for sudden cardiac death and findings of IVUS and optical coherence tomography (OCT) suggest that SCAD results from hematoma between adventitia and media expanding to create circumferential passage within the vessel wall extending variable distance along its length dividing vessel lumen into a true and false, therefore compromising blood flow to myocardium. The end result of this hemodynamic disturbance on myocardium will depend on severity of obstruction, ischemic territory, and collaterals. The proposed mechanism for SCAD includes atherosclerotic plaque inflammation and rupture of fibrous plaque, changes in hormonal milieu and hemodynamics, enzymatic lysis by the proteases released by eosinophilic infiltrate during peripartum period, underlying vascular and connective tissue disorder, chronic inflammation, and shear and stress associated with extreme physical activity [3].

SCAD should be suspected whenever a young person presents with ACS and urgent cardiac catherization should be considered. On angiography, typical dissection flap is seen as a radiolucent line that separates the flow between the true and false lumen. Careful attention should be paid to reduce risk of iatrogenic deterioration during angiography. Different imaging modalities can be employed during cardiac catherization, namely angiography, IVUS, and OCT [2] to further define the lesions. IVUS allows for accurate evaluation and characterization of the lesion along the length of the vessel and also aids in stent deployment [7]. Another differential that is common in young patients is that of vasospastic angina; however, it is unusual for coronary vasospasm to cause left ventricular dysfunction, unless it is prolonged.

At present there is no consensus on guidelines for managing SCAD. The possible treatment options include medical therapy, percutaneous coronary intervention (PCI), or coronary artery bypass grafting (CABG). Conservative management with initial anticoagulation utilizing heparin with dual antiplatelet therapy is appropriate in patients with dissections in small-caliber distal vessels or side branches with TIMI III flow and asymptomatic hemodynamically stable patients. Some suggest to discontinue heparin if SCAD is found to be the cause of symptoms, rather than ACS. The role of statins is still under evaluation, while thrombolytics are avoided altogether due to risk of further extension of dissection [6], [8]. Beta blockade theoretically might be beneficial in SCAD as it reduces shear stress [7].

Invasive strategy with PCI or CABG is pursued when major epicardial coronary supplying large territory is involved, multiple vessels are involved, or in cases of patient being hemodynamically unstable with or without active ischemia [6], [9]. PCI may also be preferred in cases with dissections involving proximal vessels. CABG is the choice in disease of left main involvement, multivessel involvement, or failed PCI [1]. Hence management of SCAD is similar to that of ACS; however, these are all based on large observational studies with no randomized controlled trials for different regimens of management.

We decided to treat our patient conservatively on medicines alone and to continue to follow up in our clinic. This decision was made as she was asymptomatic with a chronic coronary artery dissection. This was also guided by the nonviable myocardium seen on MPI. Unfortunately, the patient was lost to follow-up and further testing and surveillance could not be carried out.

In patients with SCAD aggressive risk factor modification and guideline-based medical therapy should be initiated. It is important to counsel female patients with SCAD to use contraception and to avoid pregnancy as the risk of recurrence SCAD is high, some studies showing it to have an incidence of 25% in the peripartum period, mostly in the first 2 weeks postpartum [9]. Our patient had one prior pregnancy in the past, about 8 years previously and it is possible that she may have had a silent myocardial infarction with SCAD at that time. But it is unusual for such an event to be asymptomatic. She also never had any prior ECG done, and hence none was available for comparison.

Patients should be followed for any symptoms of recurrent ischemia. MPI is the preferred imaging modality for surveillance over coronary angiography [10] while coronary computed tomography continues to be the best modality to follow-up on SCAD cases that were managed medically since it provides non-invasive imaging of coronary artery disease. This was also shown in one study conducted by Roura et al. recently [11]. Contemporary data prefer coronary angiography after 4–6 weeks of diagnosis, to assess for resolution of the dissection, and even suggest late angiography at around 6–9 months. This is based on data which have shown late progression of dissection in some patients that may require intervention [6]. Mortality from SCAD appears low in modern series, with most deaths occurring soon after the onset of symptoms [2].

SCAD is a rare disease of young adults and presents acutely with sudden cardiac death, chest pain, ACS, and malignant ventricular arrhythmia. Our report highlights the fact that even though it is unusual and rare SCAD can be silent. A number of different predisposing factors have been reported in the literature, including chronic inflammatory state, which we believe predisposed our patient to SCAD. Once the patient survives the acute episode the prognosis is fairly good. In general treatment should be individualized, as there is no specific guideline on how to manage these patients. An aggressive strategy should be pursued if large territory is involved or the patient is hemodynamically unstable or actively symptomatic. On long-term follow-up these patients are at risk of recurrence, especially women. Therefore, it is important to counsel woman against pregnancy, which is an important risk factor in this cohort. Our patient was also found to have untreated syphilis. There is little, if any, literature on association with syphilis and coronary artery dissection. Syphilis infection has been associated with disease of the aorta but rarely has been shown to cause coronary artery aneurysm and/or dissection. Whether presence of syphilis infection in our case is of any significance to our case is unknown. Hence, more research is required to find a causal association of syphilitic infection and incidence of coronary artery dissection.

Conflict of interest

The authors declare that there is no conflict of interest.