Management of patients with SCAD

At ACC 2023, Wood said the group presented data on spontaneous coronary artery dissection (SCAD) patients with reduced left ventricular ejection fractions (LVEF).

"We found these were younger patients that were more likely to have pregnancy associated SCAD and were more likely to have involvement of the left anterior descending coronary artery. The good news was that the majority of these patients actually demonstrated improvement or normalization off their LVEF when they were seen on follow-up," Wood explained. 

She said this is something that has been seen across studies where SCAD patients do recover their left ventricular systolic function more completely than patients with atherosclerotic coronary artery disease who present with acute myocardial infarction.

How to manage SCAD patients

Wood said at Mass General, any patient suspected of having SCAD will be sent to the cath lab for angiograms. Cath lab teams also should be prepared to intervene with stenting if the level of dissection is serious enough.

"If it appears that the patient is stabilizing clinically and they are not having ongoing chest pain, they do not have ongoing ST-elevation and they are not in cardiogenic shock, then we can typically manage that patient conservatively," Wood explained.

She also said if a patient has preserved coronary blood flow in an artery of TIMI 2 or better, they usually do not intervene. But if the patient has a TIMI flow of 0 or 1, depending on the appearance of the lesion, attempts are made to revascularize the patient. 

There are several factors that come into play in determining if a SCAD patient should be stented or not.

"SCAD occurs because there is something wrong due to a longer-term connective tissue disorder and there is something going on with the wall of the blood vessel. This can make passing a wire through the vessel more difficult to deliver a stent," Wood explained. "Also, patients with SCAD are more likely to have tortuous or very curly arteries, and stents are straight, so we sometimes have a great deal of difficulty placing anything other than a short stent into a lesion."

The use of shorter stents can cause additional problems, including what Wood calls the "toothpaste phenomenon." This is where the balloon inflation to deliver a stent pushes on a tear or hematoma (like pushing toothpaste in a tube), causing it to progress further down the vessel away from the stent. To prevent this, she said the proximal tip of the hematoma needs to be stented first, and then the center of the lesion. Or, if the anatomy allows, a longer stent can be used to cover the entire lesion and parts of the vessel both proximally and distally from the dissection.

Type 2 SCAD lesions, which are hematomas that are not torn open, are more likely to be pushed further down during stenting, Wood said. In these lesions, she said it is important to completely cover the lesion and then some on both sides.

While noninvasive computed tomography (CT) angiograms are useful for following patients with known SCAD, she said there are still some significant limitations on CT that impact their ability to make a definitive diagnosis.

Managing SCAD patients conservatively

Leaving the patient alone and taking a wait and see approach can be done in stable patients, Wood said. One study by Jacqueline Saw, MD, and her group at Vancouver General Hospital and St. Paul’s Hospital, in Vancouver, Canada, that analyzed imaging of SCAD patients after 6-12 weeks of conservative management showed over 90% of their SCAD lesions healed spontaneously.   

Wood said following these patients with CT makes sense to monitor the healing process, or to check when the patient presents with new symptoms that might be related to SCAD.

"That is actually a great time to use a CT angiogram, because now we know where to look," she said. 

When there are no clear culprit lesions causing chest pain or a heart attack, an MRI can also help show anatomy and physiological function and blood flow in the myocardium to help sort out the cause. This is especially true in women diagnosed with myocardial ischemia with no obstructive coronary arteries (INOCA), or myocardial infarction with non-obstructive coronary arteries (MINOCA). These conditions also occur primarily in women with no apparent blockages in their coronary arteries. Wood said SCAD can also can become MINOCA depending on how severely a tear in the blood vessel blocks a coronary artery.

"A lot of times SCAD can cause a myocardial infarction, and yet we have TIMI 3 flow, and only a mild overall change in the diameter of the vessel, so we think that there might be other factors involved, such as endothelial function at play," Wood explained.

Increased recognition of SCAD, INOCA and other rare presentations making cardiologists look closer

Wood said there has been a a major increase in awareness of other causes of ischemia and myocardial infarction that are not related to the common cause from atherosclerotic lesions. This has made cardiologists spend more time and dig deeper with patients who do not have an evident blockage. Rather than rushing to discharge the patient and telling them the symptoms are all in their head, as was often done in the past, this additional assessment can determine if chest pain is being caused by SCAD or other atypical causes.

Wood said the rising use of high sensitivity troponin blood tests has also helped confirm there is indeed a cardiac perfusion problem with a patient. 

"With the use of high sensitivity troponin, we are picking up more acute coronary syndromes that are being labeled as a non-STEMI, which in the past may have been called things like unstable angina. Now we know when we see a positive troponin we really need to search for a reason why it is there," Wood said. 

She credits researchers who, over the past decade or so, have painstakingly looked for SCAD on imaging to confirm its existence and to show other cardiologists what to look for. This research has not only led to recognition of SCAD in women, but also in men. This is largely because SCAD was not understood  previously and no one knew what to look for so it was overlooked, Wood explained. Today, imaging techniques can identify patients with SCAD, INOCA and MINOCA. 

"It is really important to understand that there are sex differences and that we now have a more robust tool kit to really identify why individuals are having symptoms in the absence of obvious coronary disease. That has really been a game changer in the way that we treat women, and men, who present with chest pain," Wood said.