Spontaneous Coronary Artery Dissection Treated with Direct Coronary Stenting

Background

Spontaneous coronary artery dissection (SCAD) is a rare emergency condition characterized by a non-traumatic and non-iatrogenic tear of the intima of a coronary artery, with an estimated incidence of 1–4% [1]. Most cases occur in females and there appears to be a predilection for the left coronary vasculature in females compared to right coronary vasculature in males [2–5]. Although its pathogenesis is not fully understood, an intimal tear or bleeding of the vasa vasorum has been proposed [6]. Risk factors include connective tissue disorders such as Ehlers-Danlos syndrome and Marfan syndrome, as well as physical stress, emotional stress, or hormonal states [7]. Symptoms depend on the severity of the dissection and may range from exertional chest pain to sudden cardiac death.

Because definitive diagnosis is often made during coronary angiography, it is believed that its incidence is underestimated [8,9]. Diagnosis can also be made with intravascular ultrasound and optical coherence tomography, but coronary angiography remains first line for diagnosis [1]. We present the case of a 39-year-old healthy woman who presented to the Emergency Department with severe anginal chest pain and dyspnea with electrocardiographic and biochemical evidence of acute coronary syndrome. She had emergent left heart catheterization, which revealed left anterior descending coronary artery dissection, and was treated with stent placement, dual antiplatelet therapy, beta-blockers, and high-intensity statin, which led to complete recovery.

Case Report

INVESTIGATIONS:

An electrocardiogram (ECG) revealed anterior precordial ST-segment elevation and T wave inversions in the anterior, inferior, and lateral leads (Figure 1). Cardiac enzymes revealed troponin I of 1.18 (normal <0.06 ng/ml), CK-MB of 8.8 ng/ml (normal 0.6–6.8 ng/ml), and elevated percentage MB relative index of 4.6% (normal 0–2.5%). Complete blood count, lipid panel, and comprehensive metabolic panel were essentially normal.

DIFFERENTIAL DIAGNOSIS:

Based on the characteristic angina-type chest pain and ischemic findings on ECG, our initial diagnosis was ST-elevation myocardial infarction (STEMI). Myopericarditis and takotsubo myopathy were felt to be less likely due to lack of supporting data from the patient’s history. We considered aortic dissection, but equal blood pressure in both arms and the lack of an enlarged mediastinum on x-ray made this less likely. Despite no known history of connective tissue disorder, recent excess emotional or physical stress, given the presentation of a young woman with no cardiac risk factors presenting with acute chest syndrome, SCAD was considered.

TREATMENT:

The patient had emergent coronary angiography, which demonstrated 99% stenosis of the distal third of the left anterior descending (LAD) coronary artery, with a diffuse, long, smooth tubular lesion (thought to be due to intramural hematoma) with no visible dissection plane (Figure 2). There was TIMI grade 1 flow in the distal LAD coronary artery. The remainder of the coronary vessels were completely normal. Given that the patient had continued symptoms despite maximal anti-anginal therapy with TIMI grade 1 flow noted, the decision was made to perform percutaneous coronary intervention. A 2.0×30 mm Onyx drug-eluting stent was placed with 0% residual stenosis and restoration of TIMI 3 blood flow (Figure 3). She was started on beta-blocker, high-intensity statin, and dual antiplatelet therapy with aspirin and prasugrel.

OUTCOME AND FOLLOW-UP:

A post-percutaneous coronary intervention (PCI) echocardio-gram revealed normal left ventricular systolic function and no regional wall motion abnormality. The patient subsequently recovered fully and was discharged on dual antiplatelet therapy (aspirin and clopidogrel) and statin therapy. Follow-up ECG demonstrated normalization of ST segments, without evidence of myocardial infarct pattern (lack of the development of q-waves) (Figure 4).

Discussion

SCAD is an uncommon etiology of acute coronary syndrome, with symptoms ranging from angina, dyspnea, and diaphoresis to sudden cardiac death, depending on the extent of the dissection [9]. Its incidence accounts for about 1–4% of cases of acute coronary syndrome, particularly among young women with little or no risk factors for atherosclerosis, as was the case in this patient [1]. It is responsible for up to 35% of all cases in women <50 years of age presenting with acute coronary syndrome, according to the American Heart Association scientific statement in 2018 [1]. Our patient exhibited findings consistent with type 2 coronary artery dissection with diffuse, long, smooth tubular lesions as a result of intramural hematoma, without a visible dissection plane. This is the most common type of SCAD, occurring in approximately 67% of cases. Type 1, which occurs in 29% of cases, usually appears as a longitudinal filling defect in which contrast stains the arterial wall, giving the appearance of a double lumen. Type 3, which is least common, mimics atherosclerosis, giving it’s the appearance of multiple focal tubular lesions from an intramural hematoma [10]. The diagnosis can be easily missed or delayed, as young patients without cardiac risk factors are often classified as low risk using risk stratification tools such as Heart Score [11,12]. The pathogenesis is poorly understood, but there seems to be an association with abnormal shear forces and changes in the arterial wall [6]. Several factors have also been associated with SCAD, including use of oral contraceptive pills, heavy exercise, fibromuscular dysplasia, blunt chest trauma, cocaine use, connective tissue disorders such as Marfan syndrome and Ehlers-Danlos syndrome, and some inflammatory diseases such as Kawasaki disease, sarcoidosis, and systemic lupus erythematosus [7]. The diagnosis of SCAD is based on coronary angiography and intracoronary imaging, including optical coherence tomography (OCT) and intravascular ultrasound (IVUS), which can image the arterial wall layers [7]. However, OCT and IVUS are not readily available and are associated with other risks and costs. Therefore, coronary angiography is still the mainstay of diagnosis despite its limitation in imaging the arterial wall. Treatment options include conservative management or emergent revascularization with PCI and CABG. A conservative approach can be considered in patients with non-critical luminal obstruction, TIMI grade 3 flow, and stable clinical symptoms and hemodynamic findings [3,8]. Some studies have shown that PCI is associated with high failure rates and complications, and does not protect against recurrent SCAD [3,8]. In a prospective study by Saw et al., during which 327 patients with SCAD were followed up for a mean period of 3.1 years, the recurrence rate was 10.4%; of note, adequate blood pressure control and use of beta-blocker seemed to be protective in this cohort of patients [13]. However, PCI may be necessary for those presenting acutely with symptoms of refractory ischemia and hemo-dynamic compromise.

Conclusions

SCAD is a rare condition that can present with severe complications such as myocardial infarction, congestive heart failure, and sudden cardiac death. It often presents with clinical symptoms and electrocardiographic and laboratory findings identical to a transmural myocardial infarction related to plaque rupture. Percutaneous coronary intervention may be considered in patients with hemodynamically unstable, compromised coronary artery TIMI flow grade, or those with persistent ischemia despite maximal medical therapy, provided there is suitable coronary anatomy.