Both Doubts and Hope for Coronary Stents in Lipid-Rich Culprit Lesions

Batya Swift Yasgur MA, LSW

April 13, 2020

A form of intracoronary imaging that provides clues about the lipid content of target lesions — and therefore, possibly, its vulnerability to rupture — made no significant difference to periprocedural or long-term outcomes of treatment with contemporary drug-eluting stents (DES), in a recent analysis from a prospective registry.

Casting a positive light on the results, authors of the published report concluded that such percutaneous coronary intervention (PCI) of lipid-rich plaque (LRP) by near-infrared spectroscopic (NIRS) imaging did not have an adverse effect on clinical outcomes.

That's despite some concerns from pathologic studies that DES stenting of LRP culprit lesions may worsen outcomes by promoting distal embolization and impairing site healing, write the authors, led by Myong Hwa Yamamoto, MD, New York-Presbyterian Hospital/Columbia University Medical Center, New York City, in their report, published in the March 31 issue of the Journal of the American College of Cardiology.

"The focus of the current report is on the outcomes of PCI, comparing short- and long-term outcomes after stenting lesions with high lipid content to the outcomes of patients who had stenting of lesions with low lipid content," senior author Giora Weisz, MD, Montefiore Medical Center, Bronx, New York, told theheart.org | Medscape Cardiology.

"We found that there is no increased risk" for adverse periprocedural or long-term outcomes, and that "it is safe to put in a stent to treat a coronary lesion that contains a large amount of lipid," said Weisz, who is also on the faculty of the Cardiovascular Research Foundation, New York City.

In the analysis of 1621 cases of PCI documented in the Chemometric Observations of Lipid Core Plaques of Interest in Native Coronary Arteries Registry (COLOR), major adverse cardiac events (MACE) occurred in 18% of patients over a median follow-up of 732 days. MACE consisted of cardiac death, myocardial infarction (MI), definite or probable stent thrombosis, or unplanned revascularization or rehospitalization for progressive angina or unstable angina.

Of the coronary lesions involved in the MACE, 8.3% were culprit lesions, 10.7% were nonculprit lesions, and 3.1% were indeterminate.

Using NIRS to delineate LRP, the researchers saw that the 2-year rate of culprit-lesion-related MACE was not significantly associated, in an adjusted analysis, with maximum lipid core burden index (LCBI) within any 4-mm-long treated vessel segment (MaxLCBI4 mm).

Nine patients (0.45%) experienced complications from NIRS imaging, of whom one had a periprocedural MI and one needed emergency bypass surgery.

"The results were not favorable," writes Steven E. Nissen, MD, Cleveland Clinic and Case Western Reserve University, in an accompanying editorial. "There was no relationship between lipid-rich plaque and clinical outcome, and the imaging procedure itself was associated with some harm."

Speaking with theheart.org | Medscape Cardiology, Nissen said that "the whole field of vulnerable plaque imaging has just not worked out, and very concept of an entity called 'vulnerable plaque' is flawed."

Part of the fallacy, he said, is that images of supposedly vulnerable plaque are static, but the lesions change over time. "How can you predict outcome if what you're looking at is dynamic and constantly changing?"

This concept has led to a series of "failed studies" that assume that "there's some plaque sitting out there that can cause heart attacks, and if we can find it and stent it, we can prevent the outcome," Nissen said. "But many patient factors are involved, and if we focus only on plaque, we miss the big picture."

Moreover, there is a "negative publication bias, meaning when people get bad results from studies, they tend not to publish them promptly. And although this study was completed in 2016, it is now 2020, which is 4 years later."

And although the study was large, "it was not randomized, and the results were not favorable, meaning that no relationship was found between LRP and clinical outcome," said Nissen, who added he is also "disturbed" that the imaging procedure was associated with some harm.

His editorial, he said, was intended to "put a stake in the ground and say, 'wait a minute, take a deep breath, and think more about the pathophysiology of this disorder,' which is driven by systemic factors such as inflammation, high levels of CRP [C-reactive protein], and platelet reactivity rather than morphology of the plaques," he said.

The COLOR analysis "evaluated the association between NIRS findings of treated culprit lesions and culprit-lesion-related clinical outcomes with coronary artery disease (CAD) undergoing PCI with DES," note the authors.

NIRS, they explain, calculates the lipid-burden index by measuring the fraction of pixels with a greater than 0.6 probability within a region of interest and can differentiate LRP from lipid-poor plaque using the absorption of scattered light in the near-infrared range."

Among the 1999 patients originally enrolled in the registry from 2009 to 2014, PCI was performed in 1621 patients. A total of 1189 patients underwent preculprit NIRS imaging of 1283 lesions prior to PCI; their mean age was about 64 years, 77.9% were men, and 39.4% had diabetes.

MACE events were stratified by whether they were culprit-lesion-related (that is, related to the initially treated lesion), nonculprit-lesion-related, or indeterminate.

The NIRS-determined MaxLCBI4 mm was defined as "the maximum LCBI within any 4- or 10-mm-long segment." Lesion-LCBI was defined as "the total LCBI throughout the entire lesion."

Compared with the 10.7% of patients with nonculprit-related MACE, the 8.3% with culprit-related MACE were younger, had more diabetes and prior histories of coronary revascularization — especially bypass surgery — and more often used statins and P2Y12 inhibitors.

At the 2-year follow-up, the group reported, culprit lesions associated with MACE, compared with those not associated with MACE, were found to have more complex lesion morphology, smaller final in-stent minimum lumen diameter, and less frequent use of DES (particularly second-generation DES).

In patients who underwent pre-PCI NIRS imaging (n = 1189), the 2-year rate of culprit-lesion-related MACE was not significantly associated with MaxLCBI4 mm, for a MaxLCBI4 mm per 100 hazard ratio (HR) of 1.06 (95% CI, 0.96 - 1.17; =.28), after adjustment for clinical and procedural factors.

Culprit lesions associated with MACE at 2-year follow-up were longer than those not associated with MACE, but were otherwise similar.

Only 8.3% of MACE events were related to the coronary lesion that was treated, whereas 10.7% were "unrelated to this specific segment, but rather to other spots in the coronary tree," Weisz said when interviewed. Thus, "the majority of future events are because of the disease in other segments of the coronary arteries."

Weisz described the Nissen editorial as "excellent," but noted that the term "vulnerable plaque" refers to coronary lesions "that may cause events in the future," whereas the current study does not focus on vulnerable plaques, but rather on treatment of the culprit lesion.

"Our study does not claim to give answers about vulnerable plaques. Rather, it is a prospective observation registry that demonstrated that the use of current DES is safe in the short- and long-term when treating lipid-containing lesions."

Weisz discloses serving on an advisory board for Corindus, Filterlex, and TriSol; and receiving institutional grant support from Abbott, Ancora, Corindus, CSI, Shock Wave, Svelte, and V-Wave. The other authors' disclosures are listed on the original paper. Nissen declared no relevant financial relationships.

J Am Coll Cardiol. 2020;75:1371-1382, 1383-1385. Abstract, Editorial

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