SCAD: The Heart Attack That Tears the Artery Wall, Not the Plaque

At 41, she had a heart attack. She ran four days a week, had never smoked, her cholesterol panel was unremarkable, and her blood pressure had been checked three months earlier at 116/72. The emergency angiogram showed a left anterior descending artery with a long segment of haziness and slow flow. No plaque. No clot on a broken plaque. The artery wall had torn.

Spontaneous Coronary Artery Dissection. SCAD. Most cardiologists not at academic centers see it rarely. Most women have never heard of it. It accounts for approximately 35% of myocardial infarctions in women under 50. 5 / Solid It is not a rare disease. It is a common disease in an uncommon population, and the fact that most women arrive at the emergency department without any prior awareness of it is part of why outcomes are worse than they should be.

What happens in SCAD

In a standard myocardial infarction, a cholesterol plaque ruptures. The inner contents of the plaque expose the clotting system; a thrombus forms; the artery blocks. This is the mechanism taught in every medical school. This is the mechanism the cardiology curriculum was built around. Every major intervention in the treatment of acute MI, the catheterization laboratory activation protocol, the PCI technique, the antiplatelet regimen, the anticoagulation strategy, was developed for this mechanism.

SCAD is different at the anatomical level. A tear develops in the intima or media of the coronary artery wall, creating a false lumen between the layers of the arterial wall. Blood enters the false lumen under arterial pressure and expands it. The expanding false lumen compresses the true lumen from outside. Blood flow through the true lumen is impaired or abolished. The myocardium downstream becomes ischemic. Troponin rises. The ECG may show ST changes or T-wave abnormalities. It is a real heart attack.

But the mechanism is structural wall failure, not plaque chemistry. No cholesterol. No clot on a broken plaque. The artery wall is tearing itself. 5 / Solid

The distinction is not academic. It determines whether every single intervention performed at the catheterization table helps or harms. A treatment perfectly calibrated for plaque-rupture MI is, in SCAD, a treatment calibrated for the wrong disease.

The anatomy of the tear

The intima is the innermost layer of the arterial wall, a single cell thick, separating blood from the deeper wall layers. The media lies beneath it, composed of smooth muscle cells and elastic fibers that give the artery tensile strength. The adventitia is the outermost layer.

In SCAD, the tear most commonly originates in the media or at the intima-media interface. The 2018 Hayes et al. AHA Scientific Statement on SCAD characterizes three angiographic types: Type 1 (classic, with visible intimal disruption and contrast in the false lumen), Type 2 (diffuse smooth narrowing of the vessel, the most common and most commonly missed type), and Type 3 (mimicking atherosclerosis, with focal tubular stenosis). 5 / Solid

Type 2 SCAD is the one most likely to be misidentified as atherosclerosis on a standard angiogram. The false lumen is not clearly visible; the vessel just looks narrowed. Without optical coherence tomography (OCT) or intravascular ultrasound (IVUS) during the catheterization, Type 2 SCAD can be indistinguishable from plaque disease. OCT provides cross-sectional imaging of the arterial wall at a resolution that visualizes the intimal flap and false lumen directly. At centers with SCAD experience, OCT is now standard when the angiographic picture is ambiguous in a young woman with no plaque burden.

Who gets SCAD

The demographic profile of SCAD is specific and should not be missed:

80-95% female. Mean age approximately 44. 5 / Solid Not the cardiovascular risk factor profile most physicians are watching for. The classic atherosclerotic risk factors (LDL, hypertension, smoking, diabetes) are frequently absent or mild. This is precisely why SCAD patients present to physicians who are looking for the wrong disease.

Associated conditions:

Fibromuscular dysplasia (FMD) is present in 50-80% of SCAD patients. 5 / Solid FMD is a non-inflammatory arterial disease causing a beaded or irregular pattern in arterial walls. It affects renal arteries (causing renovascular hypertension), carotid and vertebral arteries (causing dissection and stroke), and coronary arteries. Many SCAD patients have undiagnosed FMD throughout their arterial system, and identifying it requires imaging outside the coronary circulation. The coronary angiogram done during the acute MI workup sees only the coronary arteries.

Connective tissue disorders: Marfan syndrome, Ehlers-Danlos syndrome (particularly the vascular subtype), and Loeys-Dietz syndrome are overrepresented in SCAD populations. 4 / Promising These conditions weaken connective tissue throughout the body, including the arterial wall. A woman presenting with SCAD who has features of a connective tissue disorder (joint hypermobility, skin stretchiness, marfanoid habitus, history of arterial or intestinal rupture in family members) warrants genetic evaluation.

Peripartum period: 20-25% of SCAD cases occur in the peripartum period, with the highest risk in the first few weeks postpartum. 5 / Solid Hormonal and hemodynamic changes of pregnancy and delivery appear to predispose the coronary arterial wall to dissection. Relaxin, a hormone of pregnancy that remodels connective tissue to allow the pelvis to expand, also affects arterial wall integrity. The hemodynamic stress of labor, with cardiac output rising to 40-50% above baseline at the height of contractions, adds mechanical force to structurally weakened vessels.

Physical or emotional stress preceding the event: a precipitating stressor is documented in a substantial proportion of SCAD cases. Intense physical exertion (Valsalva-like maneuvers, weightlifting, intense aerobic effort) is a documented trigger. Emotional stressors, including grief and acute psychological shock, are also documented precipitants. This does not mean SCAD patients should not exercise. It means women with unexplained chest pain during exercise need evaluation before continuing high-intensity training, and it means that a heart attack in a young woman immediately following extraordinary physical effort or major stress deserves SCAD on the differential before plaque rupture.

Why stenting is wrong for most SCAD

This is the clinical decision where the treatment for a standard heart attack causes harm in SCAD.

In atherosclerotic plaque-rupture MI, percutaneous coronary intervention (PCI) with stenting opens a blocked artery and restores flow. Stenting works because the problem is a plaque blocking the lumen. The wire enters the true lumen, the balloon expands a stent against the plaque, and blood flows freely through the stented segment.

In SCAD, the artery wall is structurally compromised. The true lumen is compressed by the expanding false lumen. When a cardiologist passes a wire for PCI, the wire may enter the false lumen rather than the true lumen, extending the dissection. When a balloon is inflated, it may further disrupt the fragile wall. 5 / Solid

The outcome: a dissection that might have healed conservatively in four to eight weeks becomes a more extensive dissection requiring emergency surgery, or in the worst case, complete coronary occlusion. Published SCAD case series document PCI complication rates substantially higher than in standard MI PCI, including iatrogenic dissection extension in approximately 30-50% of cases where PCI was attempted.

Conservative management is the standard approach in hemodynamically stable SCAD patients: anticoagulation to prevent thrombus propagation within the false lumen, anti-ischemic medications (beta-blockers to reduce heart rate and blood pressure stress on the arterial wall), close monitoring with serial ECGs and echocardiography, and allowing the false lumen to reabsorb naturally as the intimal tear heals. Most SCAD patients treated conservatively have recovery of coronary patency on imaging at three months. 5 / Solid The false lumen resorbs, the true lumen reopens, and the artery looks normal.

Exceptions where intervention is necessary: hemodynamic instability (cardiogenic shock), ongoing ischemia of a large territory despite medical management, left main involvement. These situations require proceeding despite procedural risk, because the alternative is worse. In these cases, coronary artery bypass surgery (CABG) is often preferred over PCI because it avoids wire manipulation in the dissected segment.

The choice of antithrombotic therapy in SCAD is also distinct from plaque-rupture MI. Aggressive dual antiplatelet therapy, the standard for atherosclerotic MI, may not be appropriate in SCAD where the primary risk is propagation of the intramural hematoma, not thrombus on a broken plaque. Anticoagulation choices and antiplatelet strategies in SCAD require guidance from cardiologists with SCAD experience, not the standard MI protocol.

Recurrence and long-term surveillance

The SCAD recurrence rate at five years is approximately 14%. 5 / Solid This is substantially higher than the recurrence rate for plaque-rupture MI and reflects the underlying arterial fragility that drives SCAD. The Saw et al. series from Vancouver General Hospital, which represents one of the largest prospective SCAD registries, documented this recurrence rate across 168 SCAD patients with a mean follow-up of 3.1 years.

Recurrence may occur in the same vessel or in a different coronary artery. Physical stress events and emotional stress events are documented recurrence triggers, as they are for the index event. The clinical implication is that SCAD survivors are not cured when the acute event resolves. They carry ongoing arterial fragility that requires ongoing management.

Long-term management for SCAD survivors includes:

• Annual imaging (coronary CTA or stress imaging) to monitor healing and detect new lesions
• CTA of renal and carotid arteries to screen for FMD in other arterial territories
• Connective tissue disorder evaluation if not already performed
• Genetic counseling if a heritable connective tissue disorder is identified
• Patient education about recurrence triggers and emergency recognition of symptoms
• Beta-blocker continuation, which some evidence suggests may reduce recurrence risk
• Avoidance of high-intensity Valsalva-maneuver activities (heavy weightlifting, contact sports) in the acute recovery period; guided return to exercise with cardiac clearance and supervision

The FMD evaluation that SCAD requires

FMD in 50-80% of SCAD patients is not a statistical footnote. It is a clinical mandate. A patient who had SCAD and has undiagnosed FMD in her renal arteries may be developing renovascular hypertension that will eventually be attributed to “essential hypertension” and treated with escalating medications that miss the actual cause.

The mechanism: renal artery FMD causes narrowing or structural abnormality in the renal artery that reduces perfusion pressure to the kidney. The kidney, sensing reduced perfusion, activates the renin-angiotensin-aldosterone system, raising blood pressure systemically. That blood pressure elevation is resistant to standard antihypertensive therapy because the anatomic cause is not being addressed. Percutaneous transluminal angioplasty of the affected renal artery corrects the perfusion problem and often produces dramatic blood pressure improvement.

What FMD evaluation requires: CT angiography of the renal and carotid/vertebral arteries, looking for the classic beaded appearance or other arterial irregularities characteristic of FMD. This imaging is separate from the coronary angiogram and is not automatically ordered after SCAD unless the treating cardiologist knows to order it.

Referral to a vascular medicine specialist with FMD expertise if FMD is confirmed. General cardiology practices see FMD rarely and may not be equipped to manage the full complexity of multivessel FMD, intracranial aneurysm surveillance, or the decision algorithms around renal artery intervention.

Annual blood pressure monitoring with particular attention to treatment-resistant hypertension as a signal for new or progressive renal artery involvement.

The FMD-SCAD connection means that SCAD is not a single-artery problem. It is a systemic arterial wall problem with multiple potential manifestations, and the woman who had SCAD in her left anterior descending artery may also have FMD in her renal arteries, her carotid arteries, or her vertebral arteries. None of those are visible on the coronary angiogram done in the acute setting. They require dedicated vascular imaging at a follow-up visit.

What to do this week

If you have had a heart attack and you are female, under 55, and had little or no traditional cardiac risk factors, ask your cardiologist directly: “Has SCAD been considered as the cause, and has it been definitively ruled out by imaging?”

If you have a confirmed SCAD diagnosis and have not had CT angiography of your renal and carotid/vertebral arteries, ask when that imaging is scheduled. This is part of the standard post-SCAD evaluation and should not be deferred.

If you have been told your SCAD was an isolated event and you have been discharged without a follow-up plan beyond one appointment, seek care at an academic medical center with a dedicated SCAD program or a center affiliated with the SCAD Alliance network.

Related reading

For the broader picture of non-obstructive coronary disease in women: MINOCA: The Heart Attack With Normal Arteries.

For heart attack symptoms that don’t match the textbook: The Heart Attack Symptoms Women Actually Have.

For the cardiac risk that builds before menopause: Your Doctor Said You Are Safe Until Menopause.