OCT Appears to Help Identify ACS Patients Who Can Forgo Stenting

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Optical coherence tomography (OCT) facilitates a staged approach to managing patients with acute coronary syndromes (ACS) and a large thrombus burden. Delayed high-resolution imaging after initial angiography and thrombectomy is linked to reduced thrombus, enabling about 40% of patients to avoid stenting, asserts a prospective pilot study published online July 19, 2014, ahead of print in EuroIntervention.

Yet in a telephone interview with TCTMD, Sorin J. Brener, MD, of Weill Cornell Medical Center (New York, NY), called the study unconvincing and its results “clinically irrelevant,” though he acknowledged it may have some research interest. 

Methods
Of 852 consecutive patients with ACS (94% STEMI) treated at 2 French centers, researchers led by Geraud Souteyrand, MD, of Clermont-Ferrand University Hospital (Clermont-Ferrand, France), analyzed 101 patients who had a large thrombus burden in the culprit lesion on initial angiography and were treated with aspiration thrombectomy.

Among this group (average age 53 years; 78% men), 22% had received prehospital thrombolysis. All underwent repeat angiography with OCT after initial catheterization and were separated into 3 groups based on the timing of imaging:

  • Days 0-2 (acute)
  • Days 3-6 (early)
  • Days 7-30 (late)
 
The initial strategy involved thrombus aspiration and treatment with medical therapy (aspirin, a loading dose of clopidogrel or prasugrel, and a bolus of abciximab). Stenting was performed only if 1 or more of the components of “optimal reperfusion”—TIMI 3 flow, angina relief, and > 50% reduction in ST elevation on the postintervention ECG—were absent.
If optimal reperfusion was achieved, stenting could be either immediate or postponed to allow more time for the antithrombotic regimen to work, as determined by results of a second angiogram and OCT. The trigger for stenting was residual stenosis in the culprit lesion > 70% or evidence of plaque prolapse.

 

OCT Documents Thrombosis Decline Over Time

OCT revealed thrombus in 68.3% of patients, whereas angiography showed thrombus in 20.8%. Thrombus burden was lower in patients who underwent OCT at later intervals, affecting 94.1% of the acute OCT group, 78.8% of the early group, and 32.4% of the late group, with declining mean thrombus scores of 21.6, 13.6, and 4.2, respectively. Minimum lumen area increased and percentage stenosis decreased with longer delay to OCT. Plaque rupture was uncovered by the initial OCT in 66 patients (65.3%), and plaque erosion was diagnosed in 25 patients, 22 of them in the delayed OCT groups.

During initial hospitalization, all patients received dual antiplatelet therapy and low molecular weight heparin. Overall, 63 patients (62.4%) underwent stenting with no complications; the other 38 patient were managed medically.

OCT was performed postprocedurally in all PCI patients to assess the final stenting results. It showed limited edge dissection in 6 patients (9.5%), malapposition in 11 (17.5%), and intra-stent protrusion in 45 (moderate in 48.5% and significant in 28.5%). Median serum creatine phosphokinase was 1,257 IU and mean LVEF was 56.2%. 

Over 1-year of follow-up, there were 2 occurrences of MACE (death, recurrent MI, and revascularization): a 71-year-old man who had been managed medically experienced angina and was treated with a DES, and an 83-year-old man who had undergone angioplasty had ischemic ACS at 8 months. There were no cases of sudden death or MI. LVEF trended higher in the delayed OCT groups (57.1 ± 7.9% for early and 59.1 ± 10.2% for late vs 52.9 ± 10.2% for acute).

Contemporary Antithrombotic Therapy Enables Deferral

The main finding, the authors say, is that by using “a staged approach with invasive management selectively guided by OCT combined with optimal antithrombotic therapy, nearly half of the ACS patients selected for this form of management [ie, those with large thrombus burden] were safely treated without a stent.”

Pathology and imaging studies show that ACS events are most often due to plaque rupture or erosion, they observe, adding that when they result in a large thrombus burden, stenting “incurs a risk of no-flow, distal embolization, and [stent] malapposition.”

Dr. Souteyrand and colleagues assert that although culprit lesion stenting has been the evidence-based standard of care for ACS patients, “new treatment strategies are emerging.” Contemporary antithrombotic therapy including glycoprotein IIb/IIIa inhibitors, dual antiplatelet regimens, and anticoagulation “facilitates the safety of an observational approach, minimizing the risk of early thrombosis,” they say.

In addition, the authors write, newer-generation OCT is faster and simpler to perform and “enables analysis not only of thrombus burden but also of the ACS culprit lesion.” This imaging can guide treatment, optimize stenting, and sometimes allow for either temporary or long-term postponement of stenting in favor of medical therapy, they add.

However, the optimal time interval to OCT imaging and the appropriate OCT criteria to guide treatment remain unknown, they acknowledge. 

Finally, the authors observe that the “proof-of-concept study was designed to assess feasibility and safety, and a larger substantive trial will be needed to evaluate the role of OCT-guided treatment decisions in ACS patients with [a] large thrombus burden. A randomized trial with surrogate health outcomes, such as with MRI for infarct size at 30 days, may be the next logical step.”

Strategy Already Found Wanting

Dr. Brener said he found it difficult to determine what question the authors were trying to answer, suggesting that “therapy was not really directed by OCT.”

The management algorithm presented in the paper was likely constructed after the fact, he asserted, noting that it would never be approved by a hospital IRB. Moreover, he said, “Nobody would leave TIMI 2 lesions untreated, and nobody would keep patients in the hospital for [a median of] 9 days to repeat OCT, and they certainly wouldn’t send them home in the meantime. So this is divorced from clinical reality.”

Another clue to the study’s implausibility, he noted, is that if it had been exploring the optimal delay to OCT, the investigators would have included equal numbers of patients in each temporal group. The fact that they did not suggests that there were reasons for the timing of the imaging in individual patients, but these are unknown.

In addition, Dr. Brener observed, it has long been clear that thrombus burden diminishes with time, and OCT is not needed to confirm that. More important, the hypothesis that PCI can be deferred has been repeatedly tested and found wanting, he said, “so this is déjà vu all over again.” 

Casting further doubt on the study strategy, he said, is the 7,000-patient TASTE trial, which found no mortality benefit of thrombectomy in STEMI.

 


Source: 
Souteyrand G, Amabile N, Combaret N, et al. Invasive management without stents in selected acute coronary syndrome patients with a large thrombus burden: a prospective study of optical coherence tomography guided treatment decisions. EuroIntervention. 2014;Epub ahead of print.

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OCT Appears to Help Identify ACS Patients Who Can Forgo Stenting

Disclosures
  • Dr. Souteyrand reports receiving consulting fees from St. Jude Medical and Terumo.
  • Dr. Brener reports no relevant conflicts of interest.

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