More Evidence Linking Spontaneous Coronary Dissection and FMD

Shelley Wood

January 09, 2013

VANCOUVER, British Columbia — Another case series has confirmed the connection between spontaneous coronary artery dissection (SCAD) and fibromuscular dysplasia (FMD) and once again shows that the seemingly linked condition occurs predominantly in women [1].

Dr Jacqueline Saw (Vancouver General Hospital, BC) and colleagues describe 50 patients identified with nonatherosclerotic SCAD presenting to Vancouver General Hospital between April 2006 and March 2012 in a report published online December 19, 2012 in the Journal of the American College of Cardiology: Cardiovascular Interventions.

"The key finding here is the discovery of a very strong association between SCAD and FMD," Saw told heartwire . "We used to think it was rare, but over a quarter of young women presenting with MI had SCAD," and of those, almost 90% had FMD.

Saw and colleagues say that of the 50 patients treated over the six-year period, almost all were women (98%), all presented with MI, and the vast majority (86%) also had FMD of at least one noncoronary territory.

To heartwire , Saw explained that a diagnosis of FMD is typically made based on the telltale "string of beads" appearance on angiography--a feature that is far easier to pick up in the larger renal arteries than in the coronary vasculature. And while FMD typically affects multiple territories, it doesn't necessarily affect the whole vascular tree; the renal vasculature is the most commonly affected region, followed by the cervical and iliac vasculature. Because of the group's previous interest and experience with SCAD, Saw and colleagues now routinely screen the three vasculature territories most commonly affected by FMD and do so during the initial hospital admission. In the current series, patients who did not have noncoronary angiograms during their initial hospital admission underwent subsequent noninvasive tests, either CT angiography or MR angiography.

Saw points out that both SCAD and FMD are considered rare, yet she and her colleagues believe FMD is probably much more common than initially thought--it simply isn't being picked up by coronary angiography.

"The key is, if you've done a coronary angiogram and you've found SCAD, then yes, you should also screen for FMD, and the best way to do that would be to do a nonselective renal angiogram and an iliac angiogram, because you are in there already. A lot of centers haven't clued into that previously, so they end up bringing the patient back for further testing." Unfortunately, neither CT nor MR angiography is as sensitive at diagnosing FMD, she added.

Clinicians should understand that the link between FMD and SCAD "is very strong," Saw stressed. While there is not much that can be done about FMD--it is not curable, and the causes are unclear--it may make physicians more attuned to risk of future events. For example, Saw noted, patients with FMD are also at higher risk for intracranial aneurysm, and a diagnosis may lead to better monitoring and treatment if needed.

Commenting on the study, Dr Rajiv Gulati (Mayo Clinic, Rochester, MI), who coauthored the largest series of SCAD patients published so far, said Saw et al's paper "solidifies previous findings" [2].

"It's tempting to now speculate that fibromuscular dysplasia is the underlying disease process that predisposes coronary arteries to dissection," he told heartwire . "There is growing evidence that SCAD has been markedly underrecognized as a cause of acute coronary syndromes, particularly in younger females without atherosclerotic risk factors."

The authors have reported that they have no relevant relationships to disclose.