PCI safe for treatment of nonflow-limiting vulnerable plaques: PROSPECT ABSORB
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Among patients with nonflow-limiting vulnerable plaques, PCI with a bioresorbable vascular scaffold was safe and was linked to favorable long-term outcomes, according to the pilot PROSPECT ABSORB trial presented at the virtual TCT Connect.
The findings warrant a larger randomized trial to determine whether PCI for nonflow-limiting vulnerable plaques improves clinical outcomes, Gregg W. Stone, MD, director of academic affairs for the Mount Sinai Heart Health System and professor of medicine (cardiology) and of population health sciences and policy at The Zena and Michael A. Wiener Cardiovascular Institute at Icahn School of Medicine at Mount Sinai, said during a press conference.
The researchers randomly assigned 182 patients with MI from the PROSPECT II cohort who had successful PCI of all flow-limiting lesions but had a nonflow-limiting lesion with a plaque burden of at least 65% on IVUS to receive PCI with the BVS (Absorb, Abbott Vascular) plus guideline-directed medical therapy or guideline-directed medical therapy alone. The findings were simultaneously published in the Journal of the American College of Cardiology.
“Through IVUS, [near-infrared spectroscopy] and OCT, we can identify vulnerable plaques, nonflow-limiting lesions, that place patients with those lesions at risk for future events,” Stone said at the press conference. “But the question is what to do about them. We wanted to get a sense of whether we could safely treat these plaques and enlarge the lumen using a scaffold ... which will, by inducing neointimal hyperplasia ... turn a thin-cap plaque into a thicker-cap plaque, and normalize wall stress, which should lead to stabilization of the plaque.”
The primary effectiveness endpoint of minimum lumen area on IVUS at 25 months was 6.9 mm2 in the PCI group compared with 3 mm2 in the medical therapy group (least-squares mean difference, 3.9 mm2; 95% CI, 3.3-4.5; P < .0001), Stone said at the press conference, noting the PCI group had an average neointimal hyperplasia “neocap” of 210 m.
The primary safety endpoint of target lesion failure, defined as cardiac death, target vessel-related MI or clinically driven target lesion revascularization, at 24 months did not differ between the groups (PCI, 4.3%; medical therapy, 4.5%; P = .96), according to the researchers.
In addition, Stone said, lesion-related MACE at a median of 4.1 years was numerically lower in the PCI group (4.3% vs. 10.7%; OR = 0.38; 95% CI, 0.11-1.28).
“The outcomes were generally better than we have seen with BVS in the past, and that is in part because ... this was image-guided implantation of BVS,” Stone said at the press conference. “There was only one case with strut discontinuities or malapposition. There was only one scaffold thrombosis.”
Percent diameter stenosis was 23.8% in the PCI group compared with 38.6% in the medical therapy group (P < .001), according to the researchers.
The mean age in the PCI group was 63 years and 86% were men. The mean age in the medical therapy group was 65 years and 79% were men.
“The favorable ... MACE rates observed after BVS treatment compared with medical therapy alone warrants the performance of an adequately powered randomized trial to determine whether PCI treatment of focal vulnerable plaques improves patient prognosis,” Stone said at the press conference.
Reference:
Perspective
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Robert L. Wilensky, MD
In this well-run study assessing the role of identifying potentially high-risk lesions, which are not significant either by angiography or hemodynamic assessment, treating them using a BVS reduced atherosclerotic plaque progression. Use of BVS in this patient population and lesion phenotype was safe and not associated with increased risk for coronary thrombosis. Implantation of the BVS was associated with a substantially increased minimal luminal area at the 25-month angiographic follow-up. However, PCI of angiographically mild lesions with large plaque burden was not associated with a reduction in either target lesion failure or lesion-related adverse cardiac events (both of which were nonpowered safety endpoints).
This was a relatively small study with few events in either group. The increase in MACE rate in the medical therapy group was due to an increase in progressive angina.
It is not advisable to perform PCI in patients with nonflow-limiting vulnerable plaques at the current time. There are increasing data showing that the presence of a lipid-rich coronary lesion with a large atherosclerotic burden is associated with increased risk for clinical instability. The current manuscript adds to that database. However, multicenter, randomized studies, which are adequately powered to demonstrate reductions in hard endpoints, ie, death or MI, will be required before PCI should be performed on nonflow-limiting atherosclerotic coronary lesions. If the results of the current study are replicated in larger trials adequately powered for hard endpoints, then practice will be changed.
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Stone GW, et al. Late-breaking clinical trial session I, co-sponsored by JACC. Presented at: TCT Connect; Oct. 14-18, 2020 (virtual meeting).
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