ACS by Plaque Erosion? No Stent, Dual Antiplatelets May Be Enough: Early Data

Marlene Busko

September 02, 2016

ROME, ITALY — A small, 1-month pilot study hints that patients who arrive in the emergency department with ACS caused by plaque erosion, not plaque rupture, may not need to have a stent implanted. Instead, conservative treatment with antithrombotic therapy alone may be enough to restore flow at the thrombus site[1].

The study found that one in four patients with ACS had plaque erosion, which agrees with what was seen in pathology studies, according to the researchers, but it also showed for the first time that plaque erosion can be distinguished from plaque rupture by optical coherence tomography (OCT) in living patients. If confirmed, such patients might be spared from having a stent, plus any stent-related complications, they say.

Dr Ik-Kyung Jang

"Antithrombotic therapy with aspirin and ticagrelor [Brilinta, Brilique, Possia, AstraZeneca] without stent implantation effectively reduced thrombus volume and increased flow area without recurrent ischemic events at 1 month," Dr Ik-Kyung Jang (Harvard Medical School, Boston, MA) summarized, presenting the findings to the press prior to a hot-line session at the European Society of Cardiology (ESC) 2016 Congress.

However, these are early days, he acknowledged, and randomized trials are needed to confirm these findings and look at long-term results, he said.

The study by co–principal investigators Jang and Dr Bo Yu (Harbin Medical University, China) was simultaneously published in the European Heart Journal.

Virtually all the patients had STEMI, press-briefing comoderator Dr Andreas Baumbach (Spire Bristol Hospital, UK), noted to heartwire from Medscape. These patient come to the hospital with chest pain and need immediate lifesaving treatment, and an angiogram alone can't distinguish plaque erosion, he continued, although this may be suspected in certain younger women, for example. This study says that "you can't say this patient has a plaque erosion after the angiogram; you need OCT to define whether there is a problem that requires stenting," he said, cautioning that, as the researchers admitted, further study is needed to see if this less invasive treatment approach for patients with plaque erosion leads to long-term successful outcomes.

Dr Patrick Serruys (Erasmus Medical Center, Rotterdam, the Netherlands), assigned discussant at the hot-line session, echoed these views. "It is nice to say that you can avoid the surgery . . . but this is just a proof-of-concept study," he too warned, adding that the researchers acknowledge 11 study limitations, including that it was unblinded and nonrandomized. "The good news is that the incidence of plaque erosion is 25%," he said, but "measuring thrombus is not an easy task." However, "this is not the final word," he concluded, congratulating Jang and Yu and colleagues for this groundbreaking study.

Proof-of-Concept Study

"Plaque rupture has been well-characterized in patients in autopsy studies, but plaque erosion, on the other hand, has never been characterized in patients," Jang explained to the media.

The researchers hypothesized that OCT might allow clinicians to distinguish plaque erosion from plaque rupture, due to its different morphological characteristics (preserved vascular integrity, larger lumen, and visible platelets), and then the plaque erosion might be stabilized by effective antithrombotic treatment without implanting a stent.

To test this, they performed an uncontrolled, prospective proof-of-concept study in patients with ACS including STEMI, who were seen at a single center in Harbin, China, from August 2014 to April 2016.

They identified 405 patients who had analyzable OCT images, and of these, 103 patients (25.4%) had plaque erosion, whereas 60.7% had plaque rupture and the rest had neither.

All patients received dual antiplatelet therapy (DAPT) with aspirin (300 mg) and ticagrelor (180 mg), along with unfractionated heparin (100 IU/kg) prior to catheterization. They underwent transfemoral or transradial coronary angiography, and at the discretion of the treating cardiologist, they also received a GP IIb/IIIa inhibitors (63% of patients) or had manual aspiration thrombectomy (85%).

Of these, 60 patients with plaque erosion formed the study cohort: they had a residual diameter stenosis of <70% on angiogram with TIMI flow grade 3 and were stable and asymptomatic.

The patients received unfractionated heparin or low-molecular-weight heparin for 3 days and continued treatment with DAPT (with aspirin [100 mg/day] and ticagrelor [90 mg, twice per day]).

Patients without recurrent ischemia were discharged on day 5, and all the patients had a repeat angiography and OCT at 1 month.

At baseline, the patients had a mean age of 53 and 85% were male. Most (70%) were smokers, and 31% had hypertension.

A total of 55 of the 60 patients completed the 1-month follow-up.

A total of 47 of 60 patients (78%) had a >50% reduction of thrombus volume measured by OCT at 1 month, the study's primary end point.

Moreover, 22 of 60 patients (34%) had no visible thrombus at 1 month.

The median thrombus volume decreased from 3.7 mm3 to 0.2 mm3 (P<0.001), and the median minimal flow area increased from 1.7 mm2 to 2.1 mm2 (P=0.002).

One patient died of gastrointestinal bleeding, another patient required repeat PCI, and the rest of the patients remained asymptomatic.

OCT "Absolutely Necessary" Now; Future Research May Find Biomarkers

"It may not be easy for those people without too much experience to interpret OCT, but in collaboration with MIT, where OCT was developed, we have developed a computer-aided diagnostic algorithm," which should make it easier to diagnose the patient, Jang said at the press briefing.

"At the present time, OCT is absolutely necessary" to identify the patients who might benefit from antithrombotic therapy alone, according to Jang. However, previous pathology studies have shown that erosion is more frequent in young women who smoke and have hypertension.

"We are trying to find biomarkers to differentiate patients with plaque erosion vs plaque rupture, and we are in the process of analyzing . . . 600 patients [with autopsy data] to identify how you can identify them early on," Jang said.

"It is our hope to identify those patients with ACS caused by plaque erosion up front," so that they could be triaged to avoid the trip to cardiac cath lab and stent implantation and instead be given a noninvasive antithrombotic therapy strategy, he said.

EROSION was supported by AstraZeneca and the National Natural Science Foundation of China and by a Harbin Medical University Innovative Scientific Research grant. Jang has received an education grant and consulting fees from St Jude Medical. The coauthors report no relevant financial relationships.

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