What is Spontaneous Coronary Artery Dissection (SCAD)?
Spontaneous coronary artery dissection (SCAD) occurs when a separation or bleeding develops within the wall of a coronary artery – one of the blood vessels that supplies the heart muscle. Blood can collect within the artery wall and form a haematoma, which narrows or blocks the artery and reduces blood flow to the heart.
SCAD is a cause of acute coronary syndrome and most commonly causes a heart attack. It can also cause abnormal heart rhythms, cardiac arrest, heart failure and, in rare cases, death.
SCAD is different from the more common form of heart attack caused by fatty plaque building up in the arteries (atherosclerosis). It often affects people who have few or none of the traditional risk factors for coronary artery disease. Correct diagnosis matters because treatment for SCAD can differ from treatment for atherosclerotic heart attack.
If you think you or someone else may be having a heart attack, call Triple Zero (000) immediately. Do not drive yourself to hospital.
Who does SCAD affect?
SCAD can affect people of any age or sex, but the vast majority of people diagnosed are women. Studies report that approximately 80–95% of people with SCAD are women.
It most often occurs in women in their 30s - 60s, although younger and older women can also be affected.
SCAD is an important cause of heart attack in younger women and during pregnancy or the postpartum period with one study reporting that it accounted for 43% of pregnancy-associated heart attacks (Hayes SN et al. 2018).
What causes of SCAD
The underlying cause of SCAD is not yet fully understood. Current evidence suggests that SCAD is likely to result from a combination of an underlying vulnerability in the artery wall and, in some people, an additional physical or emotional trigger. Many people have no identifiable trigger, and SCAD is not considered to be caused by an unhealthy lifestyle.
Conditions and circumstances associated with SCAD include:
- Fibromuscular dysplasia (FMD) – a non-atherosclerotic condition affecting the walls of medium-sized arteries. FMD is the vascular condition most commonly associated with SCAD.
- Pregnancy and the postpartum period – pregnancy-associated SCAD is uncommon, but it is an important cause of heart attack during and after pregnancy.
- Physical stressors – including unusually intense exertion or heavy straining in some cases.
- Severe emotional stress in some cases.
- Hormonal and genetic factors – these are being actively researched, but their precise roles are not yet established.
- Rare inherited connective tissue or vascular disorders, such as vascular Ehlers–Danlos syndrome, Marfan syndrome or Loeys–Dietz syndrome. These account for only a small proportion of SCAD cases.
- Inflammatory conditions and stimulant or recreational drug use have been reported in some people with SCAD, but an association does not necessarily mean that they directly caused the event.
FMD and screening of other arteries
Because SCAD can be associated with FMD, aneurysms and other abnormalities in arteries outside the heart, imaging of arteries from the brain to the pelvis is commonly recommended after SCAD. The type and timing of imaging should be discussed with the treating cardiologist. FMD is associated with SCAD, but it should not be described as a proven cause of every SCAD event.
Signs and Symptoms of SCAD
SCAD usually presents as a heart attack, so the warning signs are those of a heart attack. Chest pain or discomfort is the most common symptom in both women and men. Symptoms can begin suddenly and may include:
- Chest pain, pressure, tightness, heaviness, burning or discomfort
- Pain or discomfort in one or both arms, the shoulders, neck, jaw, back or upper abdomen
- Shortness of breath
- Sweating or clammy skin
- Nausea or vomiting
- Dizziness, light-headedness or fainting
- A rapid, pounding or irregular heartbeat
- Unusual or extreme fatigue
Not everyone experiences the same combination or intensity of symptoms. Women may experience chest pain together with symptoms such as breathlessness, nausea, back or jaw discomfort and unusual fatigue. Do not dismiss symptoms because you are young, fit or have no known heart disease risk factors.
Call Triple Zero (000) immediately if you think you may be having a heart attack, even if you are unsure. Every minute matters.
How is SCAD diagnosed?
SCAD can be difficult to diagnose and may be mistaken for atherosclerotic coronary artery disease. Initial assessment generally includes an electrocardiogram (ECG), blood tests including troponin, and clinical assessment. Coronary angiography is the main test used to diagnose SCAD.
Sometimes additional imaging is needed when the diagnosis is uncertain. Intravascular ultrasound or optical coherence tomography can provide more detail but must be used cautiously because instruments and contrast within a fragile artery can extend the dissection. CT coronary angiography may be useful in selected situations or follow-up, but it can miss SCAD in smaller coronary arteries and cannot reliably exclude the condition.
How is SCAD treated?
Treatment depends on the location and extent of the dissection, blood flow through the artery, ongoing symptoms, heart function and the person’s overall clinical stability. SCAD treatment must be individualised by a cardiology team experienced in the condition.
Conservative treatment
For most clinically stable people with adequate blood flow, careful monitoring and medication are preferred because most SCAD-affected arteries heal naturally over time. Monitoring in hospital is important because a small proportion of people experience early extension of the dissection or a new event.
Medication
Medication is tailored to the individual. A beta-blocker may be prescribed to reduce blood pressure and stress on the artery wall and has been associated with a lower risk of recurrence in observational studies. Other medicines may be used to manage chest pain, high blood pressure or reduced heart function.
The most appropriate type and duration of antiplatelet treatment after SCAD remain uncertain and may differ depending on whether a stent was inserted. Statins are not routinely prescribed solely because a person has had SCAD, as SCAD is not caused by cholesterol plaque; however, they may be appropriate when there is another indication such as high cholesterol or co-existing atherosclerotic disease. Do not start, stop or change any medicine without discussing it with your cardiologist.
Angioplasty, stenting and bypass surgery
Angioplasty and stenting are not routine first-line treatments for stable SCAD. Passing a guidewire or inserting a stent can extend the dissection or intramural haematoma, and the affected artery may be difficult to treat. Intervention may nevertheless be necessary when there is ongoing or severe ischaemia, haemodynamic instability, reduced blood flow in a major artery or other high-risk features.
Coronary artery bypass graft (CABG) surgery may be considered in selected high-risk cases, such as extensive disease involving a major proximal artery or when angioplasty is unsuccessful or unsuitable.
Recovery and follow-up
Cardiac rehabilitation
People recovering from a SCAD heart attack should be referred to cardiac rehabilitation. A program that understands SCAD can provide supervised and individually tailored exercise, education, medication support and help with emotional recovery. If a program is not familiar with SCAD, ask the treating cardiologist to provide individual exercise guidance.
Exercise and everyday activity
Regular physical activity remains important, but return to exercise should be gradual and tailored to the individual. Avoid sudden extreme exertion, heavy lifting that requires straining or breath-holding, and high-intensity activity until cleared by the treating team. Advice should take account of previous fitness, heart function, blood pressure and any associated vascular condition.
Chest pain after SCAD
Recurrent chest pain is common after SCAD and does not always mean that another dissection has occurred. However, new, severe, persistent or concerning chest pain must be assessed urgently because recurrent SCAD and other heart conditions need to be excluded. Call Triple Zero (000) for symptoms that may indicate a heart attack.
Emotional recovery
A SCAD event can be frightening and unexpected. Anxiety, depression and post-traumatic stress symptoms are common, particularly during the first year. Speak with your healthcare team about psychological support, cardiac counselling and peer support.