Hypothyroidism and Spontaneous Coronary Artery Dissection following Kayaking: Dual Pathology or a Unifying Diagnosis?

A 54-year-old woman presented with an episode of chest pain and collapse, 30 minutes after river kayaking. She was a smoker and was prescribed levothyroxine for hypothyroidism, which she had not taken for the previous week. On examination, she was haemodynamically stable, her blood pressure was 130/74 mmHg, heart rate 54 beats per minute, and oxygen saturation and random glucose were normal. Electrocardiography showed sinus rhythm with ST-segment elevation in the lateral leads (I and AVL) with reciprocal ST-segment depression in the inferior leads (II, III and AVF, see Figure 1). The left main stem, circumflex, and right coronary arteries were normal.

Figure 1

Emergency coronary angiography was suggestive of coronary artery dissection, with associated thrombus in the left anterior descending (LAD) artery (Panel B).

High-sensitivity troponin T peaked at 390 ng/L, and biomarkers showed TSH:85.68 mU/L and T4:3.5 pmol/L. She was managed conservatively and received aspirin 75 mg daily and ticagrelor 90 mg twice daily following initial loading doses. In view of the high suspicion of intraluminal thrombus at angiography. she also received low-molecular-weight heparin (1 mg/kg twice daily).

Echocardiography showed mild left ventricular systolic impairment with hypokinesia of the apical anterior, lateral and true apical segments. Computed tomographic coronary angiography (CTCA) 8 days later showed excellent flow in the LAD with minimal stenosis (Panel C, D).

Spontaneous coronary artery dissection (SCAD) is a rare and challenging condition with no treatment consensus. SCAD is the separation of the arterial vessel layers and can also be associated with intramural hemorrhage. Narrowing of the vessel's true lumen can cause myocardial ischemia or infarction. It is the cause of acute coronary syndrome in 0.1%–0.4% of cases [1] and has been shown to present as a ST-segment elevation myocardial infarction in 24%–87% of cases confirmed at angiography [2].. More than 90% of patients with spontaneous coronary artery dissection are women [2] with a prevalence of SCAD in women with ACS of around 22%–45% [3]. The cause of spontaneous coronary artery dissection is multifactorial. Cases are often seen after physical stress and are found to have an underlying arteriopathy, most commonly fibromuscular dysplasia [4]. The association between pregnancy and SCAD is also well documented. Physical stressors that result in Valsalva-like maneuvers that lead to an increase in thoraco-abdominal pressure or that cause a catecholamine surge can increase coronary vascular shear stress, which can precipitate dissection [2]. The typical coronary angiographic appearances of SCAD have been classified into the following types [5]:

- Type 1: Pathognomonic contrast dye staining of arterial wall with multiple radiolucencies in lumen.

A conservative approach is preferred in patients with noncritical luminal obstruction [1], while. revascularization is reserved for patients with ongoing or recurrent ischemia [3]. In prospective studies, coronary artery healing is seen in 73%–97% of cases at repeat coronary angiograpthy [2]. Percutaneous coronary intervention is challenging in SCAD and is associated with high failure rates [2] for several reasons, including the fragility of the vessel wall and the difficulty to enter the true lumen. CTCA is useful to assess recanalisation of the lumen, but alone may not reliably differentiate atheroma from dissection. Echocardiography and cardiac magnetic resonance imaging (CMR) are both important modalities for general assessment and impact of the dissection and have the added advantage of being radiation-free and safe for a condition seen in young women and in pregnancy. Hypothyroidism is known to cause haemodynamic alterations and coronary endothelial dysfunction [6], which may predispose individuals to SCAD when combined with strenuous exertion, although no current published link between SCAD and thyroid dysfunction exists.

Our patient underwent CTCA 8 days following presentation that showed excellent flow in the LAD with minimal residual stenosis. The patient was discharged home on day 8 after her admission and advised to take her thyroid replacement and cardiac medications regularly.