Bioresorbable Scaffolds May Have Role in Spontaneous Coronary Artery Dissections

Bioresorbable scaffolds are potentially useful for treating the rare patients with ACS caused by spontaneous coronary artery dissection (SCAD), according to a case report summarizing results for three patients. An expert says such patients, who tend to be younger with minimal atherosclerotic disease, may have more to gain from the disappearance of the scaffolds after 2 to 3 years, although there are limitations to the technology.

Fernando Macaya, MD, of the Hospital Universitario Son Espases (Palma de Mallorca, Spain), and colleagues reported on 3 patients who had SCAD in 3 different coronary arteries causing ACS.

• A 58-year-old man presenting with an inferior STEMI had an occluded RCA showing a large dissection on imaging. He initially received 5 Absorb BVS (Abbott Vascular) but reported rest angina 10 days later. After coronary angiography showed a narrowing of the vessel distal to the scaffolds and OCT showed an intramural hematoma after the last scaffold, another Absorb BVS was implanted. Control angiography with OCT at 6 months showed a good result in terms of vessel patency and endothelialization of the struts.
• A 43-year-old woman presenting with NSTE-ACS had a circumflex dissection. She underwent OCT-guided implantation of 3 Absorb BVS. At 6 months, a control study with OCT showed satisfactory results and strut endothelialization.
• A 55-year-old women presenting with an anterior STEMI had an LAD with a dissection and sub-occlusion as seen on angiography. She received 3 Absorb BVS. At 6 months, intracoronary imaging was unavailable but the treated vessel had a “good angiographic appearance.”

The case reports were published online ahead of the January 2016 issue of Circulation: Cardiovascular Interventions.

“To the best of our knowledge, this is the first series of patients with this pathology treated with BVS and the first report that provides detailed follow-up intion through invasive imaging,” the authors say.

Although these early results were good, they conclude, “a longer follow-up is of interest to provide more information about the natural process of disappearance of the scaffolds, as well as to better illustrate the healing concept happening in SCAD. Larger series could yield definitive data about the role of bioabsorbable coronary stents in this particular entity.”

Conservative vs Invasive Treatment

The optimal treatment approach for SCAD remains unclear, although conservative medical management is chosen for most patients because of the “proven propensity” of vessels to heal on their own, Macaya and colleagues note. “Performing percutaneous coronary intervention in patients with SCAD carries a high risk of procedural failure and usually implies implantation of several stents; thus, it should be justified.”

Commenting on the study, Rajiv Gulati, MD, PhD, of the Mayo Clinic (Rochester, MN), also underscored the risks of percutaneous intervention.

“The elevated risk of PCI complications in SCAD, coupled with generally favorable outcomes with conservative therapy suggests that caution should be used in employing an invasive strategy in patients who present with normal vessel flow,” he said in an email to TCTMD.

Nevertheless, he said, there are patients who require invasive treatment. “Thus, there certainly is a clinical need for creative invasive strategies in SCAD, including use of cutting balloons for the decompression of hematoma or extensive vessel paving with BVS as described in this series.”

When percutaneous intervention is chosen, it typically involves putting a metallic stent on vessels that have no significant atherosclerotic lesions, the authors point out, and both they and Gulati say bioresorbable scaffolds might have some particular benefits for patients with SCAD.

Gulati said that because “SCAD typically presents in younger patients, there are theoretically more years ahead for patients to experience the advantages of BVS over metallic stents, such as restoration of vasomotor function, surgical targets, etc. More so, experience suggests that when metallic stents are used in SCAD, they are frequently undersized.”

Undersizing can lead to late stent malapposition, a problem that might be ameliorated by using bioresorbable scaffolds, he said.

However, there are limitations of current bioresorbable scaffolds, including deliverability and device bulk, Gulati said. “SCAD patients have a much higher rate of severe coronary artery tortuosity, which can further hamper deliverability. More so, coronary arteries in patients with SCAD are notoriously fragile, with data showing an increased risk for iatrogenic trauma. This risk would likely be further increased with aggressive guide maneuvers that may be required for BVS delivery.”

The authors also acknowledge the deliverability issues with bioresorbable scaffolds, which “have a worse technical performance at the time of implantation, with a higher profile and lower navigability and crossability; however, the more favorable anatomy usually present in these kinds of patients (with low burden of atherosclerotic disease) overcomes this technical issue.”

Importance of OCT

In the past, diagnosis of SCAD depended on coronary angiography, but newer imaging techniques like OCT have improved diagnostic accuracy.

“A major value of using OCT in younger patients presenting with ACS is as a diagnostic tool: to diagnose SCAD rather than atherosclerosis as the cause for luminal stenosis,” Gulati said. “While an intimal dissection plane was evident on angiography in the cases presented in this series, it is important to remember that more often SCAD presents with an intramural hematoma alone, and without intimal dissection. Hematoma-related luminal compression can be indistinguishable on angiography from atherosclerotic narrowing. OCT can unambiguously visualize intramural hematoma, with an absence of atherosclerotic plaque in these situations.  Increased utilization of OCT as a diagnostic tool in younger patients with ACS is one of the reasons for growing recognition of SCAD as a cause of ACS.” 

Source: 
Macaya F, Peral V, Alameda M, et al. Bioresorbable scaffolds to treat spontaneous coronary artery dissection. Circ Cardiovasc Interv. 2016;9:e003133.

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