COLOR: PCI of Lipid-Rich Plaque Not Associated With Increased Risk of Adverse Events

WASHINGTON, DC—Two-year data from the COLOR trial suggest that coronary lesions rich in lipids can be safely treated with PCI, with investigators reporting that revascularization of lipid-rich plaque was not associated with an increased risk of periprocedural or late clinical outcomes when compared with PCI of non-lipid-rich coronary lesions.

Overall, there was no relationship between the presence of lipid-rich plaque—assessed by near-infrared spectroscopy (NIRS)—and major adverse cardiovascular events, say investigators.

“We found that it doesn’t matter, that it’s safe,” lead investigator Giora Weisz, MD (Shaare Zedek Medical Center, Jerusalem, Israel), told TCTMD. “Some people have worried that if we put a stent into a lesion filled with lipid, you have to be careful. Something bad might happen. You might have to put a stent in for the patient, but it’s not benign. We found that it’s not so bad, it doesn’t matter. I have heard colleagues of mine in the past say that even in [lipid-rich] lesions that are flow-limiting—so it needs to be treated—it might be better to do bypass surgery. But no, PCI is OK.”

Speaking with the media at TCT 2016, Weisz said the clinical impact of lipid-rich plaque, which is assessed with a combined NIRS/IVUS imaging catheter, in patients with coronary atherosclerosis undergoing PCI had not been well characterized. Furthermore, case reports and small studies have suggested that stented patients with lipid-rich plaques might be at higher risk for worse clinical outcomes after PCI.

The COLOR study included 1,899 patients with a clinical indication for coronary angiography and possible revascularization. Prior to PCI, investigators assessed the lipid content of the culprit lesions in 1,168 patients and in the nonculprit lesions in 927 patients. Individuals, the vast majority who had stable and unstable angina, were followed for approximately 2 years.

The composite primary endpoint of cardiac death, MI, stent thrombosis, revascularization, and hospitalization occurred in 14.1% of all patients, with 6.0% of events related to culprit lesion, 8.3% related to the nonculprit lesion, and 2.4% to an indeterminate lesion. When the researchers stratified lesions based on the presence of lipid-rich plaque— the maximum lipid core burden index (LCBI) per 4 mm segment (maxLCBI4mm) above and below the median was the cutoff—they did not observe a significant difference in MACE related to the maxLCBI4mm.

David R. Holmes Jr, MD (Mayo Clinic, Rochester, MN), speaking during the morning press conference, asked Weisz how a clinician would handle a nonculprit lesion—one in which he wasn’t planning on stenting—identified to have a lipid-rich coronary plaque. “Should we treat them or do we treat [the patient] with different antiplatelet therapies, or with the new cholesterol drugs?” asked Holmes. “How are we going to be guided by this? We’re doing IVUS of culprit lesions, and I’m always amazed the rest of the artery always looks like it has lots of stuff in it?”

Weisz noted that the cardiology community has been discussing the “vulnerable plaque” hypothesis for years, but it’s still unclear how these nonculprit lesions rich in lipids should be treated. They have not yet analyzed the outcomes data from the patients who underwent NIRS of the nonculprit vessel, he said, noting that there are two ongoing studies—the LRP Study and PROSPECT II—evaluating the clinical significance of NIRS-defined nonculprit lipid-rich plaques. 

To TCTMD, Weisz said the study does not support the use of NIRS in routine PCI, as the presence of lipid-rich plaque would not alter the decision to perform PCI. “We’re not saying don’t do it, but you don’t need it for the stented segment,” he said. “You might still get a lot of other important information about the patient and how to treat them from the other segments, such as those distal and proximal to the stented segment.”

From an investigational and research standpoint, Jeffrey Popma, MD (Beth Israel Deaconess Medical Center, Boston, MA), noted that the 2003 REVERSAL trial showed that high-intensity statin therapy to drive LDL cholesterol down to low levels could regress coronary plaque as assessed by intravascular ultrasound. With the introduction of the new PCSK9 inhibitors, there is now an opportunity to study whether reducing LDL cholesterol levels even further, say to 30 or 40 mg/dL, could this alter the lipid content of coronary plaques, said Popma.