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Lipid-rich plaque (LRP) was not associated with clinical outcomes after percutaneous coronary intervention (PCI), the COLOR registry team reported.

Maximum lipid core burden index (LCBI) within any 4-mm-long segment did not predict major adverse events (MACE) in the 2 years after 1,189 people underwent coronary angiography and PCI (adjusted HR 1.06 per 100-unit increase, 95% CI 0.96-1.17).

MACE -- cardiac death, MI, stent thrombosis, unplanned revascularization, or rehospitalization for progressive angina or unstable angina -- occurred in 18.0% of patients, reported Akiko Maehara, MD, of Columbia University Medical Center and the Cardiovascular Research Foundation in New York City, and colleagues.

"The current COLOR registry is the largest study to evaluate outcomes after stenting LRP-containing coronary lesions. We found no differences in the short- or long-term culprit lesion-related outcomes after stenting LRP compared with non-LRP lesions," the authors wrote in the March 31 issue of the .

This goes against earlier autopsy studies suggesting that it was unsafe to put stents in LRP.

"These findings suggest that DES [drug-eluting stent] treatment of LRP should not be withheld in LRP based solely on this ," according to Maehara and colleagues.

Comparing baseline and event-related coronary angiograms, MACE rates were:

• 8.3% for culprit (PCI-treated) lesions
• 10.7% for nonculprit (untreated) lesions
• 3.1% with indeterminate origin

LCBI, derived from near-infrared spectroscopy (NIRS), measures the fraction of pixels with probability of LRP >0.6 within a region of interest.

NIRS imaging was associated with a 0.45% complication rate: there was one peri-procedural MI and one emergent coronary bypass required.

"Essentially, for every 16 patients with a spontaneous adverse clinical outcome, one experienced a complication from the procedure," estimated Steven Nissen, MD, of Cleveland Clinic, in an accompanying editorial.

"To date, proponents of vulnerable plaque imaging have not conducted high-quality trials, and no imaging modality has demonstrated a meaningful clinical benefit," he noted. "After thousands of vulnerable plaque papers and more than 2 decades of research, we have little to show for these efforts."

COLOR was conducted at 22 U.S. sites. Enrolled were 1,621 patients with coronary artery disease who received PCI (largely with second-generation drug-eluting stents), of whom 1,189 had pre-culprit NIRS imaging prior to PCI.

Mean age was 63.9 years, and 77.9% of the NIRS imaging group were men. Nearly 40% had diabetes.

The authors acknowledged the possibilities of selection bias and unmeasured confounding in the data, given that the study was observational and did not blind operators to NIRS results.

"A quote often attributed to Albert Einstein defines insanity as 'doing the same thing over and over again and expecting different results.' That's exactly what has happened with efforts to identify the elusive entity of 'vulnerable plaque' using various coronary imaging modalities," according to Nissen.

Results from the present study had been sitting around for 4 years -- whereas a more favorable report was submitted and published within 1 year of completion, he observed. "The entire field is seemingly plagued by the vexing problem of negative publication bias."

"Now, after a long series of failures, it seems abundantly clear that the entire concept of vulnerable plaque is fundamentally flawed and reflects an overly simplistic view of the pathophysiology underlying coronary events," the editorialist said.

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