A Tad About SCAD

Spontaneous Coronary Artery Dissection and EMS

You are dispatched to an area park for a “pregnant woman with difficulty breathing.” Upon arrival, you find a 29-year-old female, Gravida 1, Para 0, AB 0, at 34 weeks gestation sitting under a tree. The patient reports to you that she and her significant other got into an argument while they were walking in the park. The patient’s partner has left the scene, but shortly afterward, the patient reports that she started to have chest pain and feel short of breath. Her vital signs are HR = 110 bpm and regular, B/P is 136/92, SpO2 is 98% on room air and the patient is breathing 28 times per minute. You begin your assessment and physical exam. She reports that she has no past medical history, and her only medications are her prenatal vitamins.

What would your differential diagnosis include? Shortness of breath due to over-exertion? Shortness of breath due to reduced oxygen reserves in the late stages of pregnancy? Anxiety attack? Probably. But what about STEMI or left main coronary artery infarction? In fact, this patient could be experiencing a rare, but serious form of myocardial infarction known as spontaneous coronary artery dissection (SCAD).

What is SCAD? As EMS, we frequently evaluate patients with the mechanism of myocardial infarction where a coronary artery becomes blocked due to a plaque-based obstruction that occurs with atherosclerosis. Most of us are familiar with aneurysms where the outer vessel wall becomes weakened or ruptures, leaking blood. But SCAD is different. With SCAD, the obstruction is a pocket of blood that forms inside the artery wall, and the tear or separation (dissection) occurs within the layers of the coronary artery wall itself.

Coronary arteries, like other arteries, have a multi-layered vessel wall. The outer layer is called the adventitia; the middle layer is called the media; and the interior layer is called the intima. Tears or pockets of blood that form within these layers can partially or completely occlude the vessel, resulting in the same reduced or loss of blood flow as an atherosclerotic blockage or aneurysm. There are different ways that a tear or malformation can occur within the vessel wall. For example, an intimal tear is a tear or rip occurs in the innermost layer of the artery. This creates an alternative path for blood to flow. There is the normal artery lumen and a false lumen created from the tear. This is referred to as a Type 1 SCAD. With this mechanism, blood flows between the layers of the artery wall. If this type of tear remains small, the patient may not even experience symptoms. However, blood that flows through this “false lumen” can clot and become a larger blockage to normal coronary artery blood flow.^1,2

Another potential mechanism is when a pocket of blood forms within the layers of the artery wall. There is no tear in the intima, so no false lumen is created, but rather a hematoma is formed which reduces or obstructs the blood flow through the artery. This mechanism can result in a Type 2, Type 3 or Type 4 SCAD. Type 2 is the most common and usually results in a long hematoma that narrows the artery but does not create a complete occlusion. Type 3 SCAD is the most difficult to diagnose and may require imaging studies inside the coronary artery to identify. Type 4 SCAD results when the hematoma becomes large enough to completely obstruct the artery.¹ (See Figure 1.)

“I didn’t hear about SCAD during training. Why not?” SCAD can occur in either men or women; but only accounts for less than 1% of all AMIs.¹ Though rare in the overall population, SCAD can cause life-threatening events in the patients it most often affects. SCAD is one of the leading causes of heart attacks in women under the age of 50 and in pregnant or postpartum women.² Research indicates the clinical implications of SCAD for pregnant women or those who are recently postpartum can be particularly severe. They are at a higher risk for compromise of multiple cardiac vessels or the left main coronary artery, an increased incidence of STEMI findings and lower ejection fraction with SCAD events.^1,3

Although heart disease is the leading cause of death for men and women in the United States, historically cardiovascular health and education for women has received less attention.⁴  So much so that in 2004, the American Heart Association launched its “Go Red for Women” campaign as a means of promoting educational initiatives and awareness about cardiovascular health for women.⁵  SCAD is a condition that most often affects women. Up to 90% of SCAD patients are women between the ages of 47 and 53.¹ As such, despite being first described in 1931, SCAD has received less attention due to its overall prevalence and it primarily affecting women.² For the EMS provider, recognizing and evaluating both genders as early as adolescence for potential cardiac issues may help increase the number of SCAD patients that are able to be identified.

Another complication of recognizing SCAD is that patients can present without traditional cardiac risk factors. Generally, when we evaluate patients for the potential of STEMI, patients have risk factors for coronary artery disease. Hypertension, elevated cholesterol, diabetes, obesity and cigarette use are all factors that EMS is trained to consider as part of a patient’s cardiac history. However, SCAD often presents without these traditional co-morbidities. Instead, patients may have a rare blood vessel condition known as fibromuscular dysplasia. Fibromuscular dysplasia causes arterial blood vessels to narrow or enlarge, most notably in the kidneys or brain, and has been linked to a significant number of SCAD patients in registries.⁶ SCAD patients may have an identified family history of a connective-tissue disorder such as Marfan syndrome; or may have a recent history of physical exertion or emotional stress; or recently used stimulants or illicit drugs. Some reports indicate there may be a relationship between SCAD and inflammatory disorders such as celiac disease, lupus, or inflammatory bowel disease; however, the available data suggests that systemic inflammatory disorders are not widespread in patients with SCAD. Some SCAD patients present with no precursors at all.^1,2 For all healthcare providers, going beyond the “typical” chest pain questions in a patient history may help identify patients at risk for SCAD.

Another barrier to identifying SCAD patients is that SCAD is not solely diagnosed on ECG criteria or laboratory values. While patients may present with STEMI ECG changes, the lack of ECG changes does not eliminate SCAD as a potential diagnosis. Often initial laboratory values show little to no elevated troponin, making diagnosis more complicated. Angiography is required to diagnose SCAD. This presents a challenge for EMS providers who lack that technology in the field. While a patient’s diagnosis of SCAD will be definitively made with angiography, EMS providers can increase their awareness of the highest risk populations and risk factors for SCAD and communicate their suspicions and findings to hospital staff more effectively.

“What are the signs and symptoms of SCAD?” Unfortunately, the symptoms of SCAD do not immediately distinguish it from other cardiac events. The most common symptoms associated with acute SCAD events are chest pain or pressure, arm, shoulder or jaw pain, shortness of breath or dyspnea, nausea, sweating, extreme fatigue, and dizziness.^1,2 While these signs and symptoms suggest a potential cardiac event, they do not specifically point to SCAD. With the barriers that already exist in identifying potential SCAD patients, it is imperative for all healthcare providers in emergency medicine to be aware of SCAD to reduce misdiagnosis.

“Does SCAD change my treatment?” Ultimately, for the EMS provider the answer to this question is “no.” However, SCAD patients do receive different treatment once at a hospital if their condition is properly identified. Although SCAD patients can present with the findings of STEMI, they may not need emergent PCI therapy. SCAD patients often have less successful results with PCI than the “typical” atherosclerotic blockage-based MI. Instead, many patients can be managed medically, and in most cases managing SCAD patients medically is preferred over immediate coronary artery catheterization.¹

EMS providers may be limited in the technologies readily available to them when compared to hospitals; however, there are things that EMS providers can do to help SCAD, and potentially all, cardiac patients.

1. While this article, and much of the current research indicates that SCAD predominantly affects women, it can affect men as well. The seemingly healthy body builder who complains of chest pain after a workout or the men’s track star that collapses during an event on a summer’s day – could it be a pulled muscle or dehydration? Yes. It could also be a serious underlying undiagnosed cardiac condition like SCAD.
2. Evaluate patients beginning in adolescence that present to EMS with signs and symptoms suggestive of cardiac for potential cardiac issues. As EMS, we need to train ourselves to get out of the mindset that someone is “too young” or “too healthy” for a serious cardiac condition. Acquiring a 12-lead on a 15-year-old female with shortness of breath may sound excessive; however, there are many cardiac issues like SCAD that go undetected because of a lack of testing.
3. Maintain a high index of suspicion for SCAD when responding to its most prevalent populations – women less than 50 years old and pregnant or recent postpartum women. These populations are at the highest risk. When responding to a pregnant female, it is easy to assume that the presenting complaint is due to the pregnancy. However, maintaining a high index of suspicion and considering potential “outside the box” differential diagnoses could save a patient’s life.
4. Do not assume that previous diagnoses the patient has received are correct. SCAD patients who have sought treatment prior to their acute event may be told that their symptoms are GERD or reflux, or other more benign conditions.

Spontaneous coronary artery dissection is rare and difficult to diagnose but increasing awareness and education can help EMS and all healthcare providers identify, evaluate, and manage these patients better.

A heartfelt thanks to Katherine Leon of the SCAD Alliance (Home – SCAD Alliance) for all her effort in making this article better. –Thank You!

References

1. Esther S.H. Kim, M. M. (2020). Spontaneous Coronary-Artery Dissection. The New England Journal of Medicine, 2358-2370.
2. SCAD Research: Spontaneous Coronary Artery Dissection. (n.d.). Retrieved from www.scadresearch.org: www.scadresearch.org
3. Neale, T. (2017, July 17). Pregnancy-Associated SCAD Is a Particularly High-Risk Subset of the Condition. Retrieved from tctmd By the Cardiovascular Research Foundation: https://www.tctmd.com
4. American Heart Association. (2021, April 13). Facts About Heart Disease in Women. Retrieved from Go Red for Women: www.goredforwomen.org/en/about-heart-disease-in-women/facts
5. Centers for Disease Control and Prevention. (2021, April 13). Heart Disease. Retrieved from Centers for Disease Control and Prevention: www.cdc.gov/heartdisease/facts.htm
6. Mayo Clinic. (2021, April 14). Fibromuscular dysplasia. Retrieved from Mayo Clinic: https://www.mayoclinic.org/diseases-conditions/fibromuscular-dysplasia/symptoms-causes/syc-20352144