Spontaneous coronary artery dissection (SCAD) accounts for 1% to 4% of all acute coronary syndrome cases, making it an uncommon but not exceedingly rare cause of heart attack. In younger women, it’s far more common than most people realize: SCAD is responsible for up to 40% of heart attacks in women under 50. The condition is also significantly underdiagnosed, meaning the true numbers are likely higher than current estimates suggest.
Overall Prevalence
SCAD occurs when the wall of a coronary artery tears spontaneously, not from a medical procedure or trauma. Blood collects between the layers of the artery wall, creating a blockage that reduces or stops blood flow to the heart. Unlike the typical heart attack caused by cholesterol plaque buildup, SCAD strikes people who often have no traditional risk factors for heart disease.
Across all heart attack patients regardless of age or sex, SCAD represents a small slice: roughly 1% to 4% of cases. That percentage climbs dramatically in specific populations. In women under 60, SCAD accounts for over one-third of acute coronary events. In women under 50, it may cause up to 40% of heart attacks. These numbers have risen steadily over the past two decades, not because the condition is becoming more common, but because doctors have gotten better at identifying it.
Who Gets SCAD
About 90% of SCAD patients are women. In a large registry of 1,173 SCAD patients, only 123 (10.5%) were men. The average age at diagnosis is around 52 for women and 49 for men. This profile is nearly the opposite of a typical heart attack, which disproportionately affects older men with high cholesterol, high blood pressure, or diabetes.
Men and women with SCAD also differ in their triggers. Women are more likely to report emotional stress before their event, with nearly 60% identifying it as a factor compared to 35% of men. Men, on the other hand, are more likely to report intense physical exertion like heavy lifting as a trigger (40% vs. 24%).
A striking number of SCAD patients have an underlying vascular condition called fibromuscular dysplasia (FMD), which causes abnormal cell growth in artery walls. One study found that 86% of SCAD patients had FMD in at least one blood vessel outside the heart. Nearly 60% had it in the arteries supplying the kidneys, about half in the arteries of the pelvis, and close to half in the blood vessels of the brain. About 14% had a brain aneurysm. Most of these patients had no idea they had FMD before their SCAD event, since FMD itself rarely causes obvious symptoms.
How Often SCAD Gets Missed
One reason SCAD appears rarer than it actually is: it’s frequently misdiagnosed on initial presentation. A study evaluating young women who came to the hospital with heart attack symptoms found that 23% of them actually had SCAD, but 41% of those SCAD cases were not correctly identified at first. The dissection can be subtle on a standard angiogram, particularly one specific subtype (type 3) where the tear doesn’t create an obvious flap or dye pattern. These patients may be told they had a “regular” heart attack, a stress-related event, or even a non-cardiac problem.
Improved imaging techniques, including optical coherence tomography and intravascular ultrasound, have helped catch cases that would have been missed a decade ago. As awareness grows among cardiologists, the reported incidence of SCAD continues to rise. The American Heart Association has acknowledged that the true prevalence remains uncertain precisely because underdiagnosis is still a significant problem.
Survival and Short-Term Outcomes
The good news is that SCAD carries a lower short-term mortality risk than a traditional heart attack. The 30-day mortality rate for SCAD is about 1.4%, compared to 4.1% for heart attacks caused by plaque rupture. Most SCAD patients survive the initial event and leave the hospital within days. The torn artery often heals on its own without surgical intervention, though some patients do require stenting or bypass surgery depending on the severity and location of the tear.
After recovery, men tend to have fewer recurring chest pain episodes than women. In follow-up data spanning about three years, roughly 11% of men returned to the hospital with chest pain compared to 25% of women. Whether this reflects differences in how the arteries heal, differences in underlying vascular conditions like FMD, or differences in reporting patterns isn’t fully clear.
Recurrence Risk
SCAD can happen more than once. Women with SCAD have a higher rate of prior heart attacks than men in the same registries (7% vs. less than 1%), suggesting that some of those earlier events may have been unrecognized SCAD episodes. Recurrence is one of the most concerning aspects of the condition because there’s no proven medication that prevents it. Most cardiologists recommend avoiding extreme physical exertion, managing blood pressure carefully, and screening for FMD in other arteries, but these strategies are based on clinical reasoning rather than large randomized trials.
The connection between SCAD and FMD also means that patients benefit from a full vascular workup after their first event. Finding FMD in the brain, kidneys, or other vessels doesn’t change the SCAD diagnosis, but it can guide monitoring and help catch complications like aneurysms before they become dangerous.
Why “Rare” Is Relative
Whether SCAD feels rare depends entirely on who you are. For a 70-year-old man with high cholesterol, it’s an unlikely diagnosis. For a 45-year-old woman with no cardiac risk factors who just had a heart attack, it’s one of the most probable explanations. The disconnect between these two realities is part of why SCAD has been historically overlooked. Cardiology was built around treating plaque-based disease in older patients, and SCAD simply didn’t fit the model.
The condition is rare enough that many emergency physicians and general cardiologists may see only a handful of cases in their careers. But it’s common enough that any woman under 50 presenting with heart attack symptoms should have it considered as a potential cause. That gap between “rare in the general population” and “common in a specific demographic” is where most of the diagnostic failures happen.