Determinants of Plaque Progression Despite Very Low Low-Density Lipoprotein-Cholesterol Levels With the PCSK9 Inhibitor, Evolocumab

Characterization of lipidic plaque features in association with LDL-C<70 mg/dL and lipoprotein(a) <50 mg/dL

BACKGROUND

The ongoing residual cardiovascular risks despite lowering low-density lipoprotein cholesterol (LDL-C) levels suggest the need to identify additional drivers associated with atherosclerosis. Circulating lipoprotein(a) [Lp(a)]promotes formation of foam cells via its proatherogenic properties. However, whether a lower Lp(a) level in combination with favorable LDL-C control could induce a more stable form of disease remains unknown. Near-infrared spectroscopy (NIRS) generates maximum lipid-core burden index in 4 mm (MaxLCBI4 mm) which is a histologically validated measure of lipidic plaque material in vivo. Therefore, the current study employed NIRS imaging to characterize lipidic plaque in association with LDL-C < 70 mg/dL and Lp(a) <50 mg/dL.

METHODS

We analyzed 439 patients with coronary artery disease (CAD) (554 de-novo target lesions receiving percutaneous coronary intervention) in the REASSURE-NIRS registry (NCT04864171). Clinical characteristics and NIRS-derived MaxLCBI4mm were compared among 4 groups according to LDL-C of 70 mg/dL and Lp(a) of 50 mg/dL.

RESULTS

Almost one-third of study subjects (33.4%) exhibited both LDL-C < 70 mg/dL and Lp(a) <50 mg/dL. They were more likely male with a lower frequency of acute coronary syndrome and lipid lowering therapies were more frequently used in those with LDL-C < 70 mg/dL and Lp(a) <50 mg/dL. On NIRS imaging analysis, a smaller MaxLCBI4mm (P < .001) and a lower frequency of MaxLCBI4mm ≥400 (P = .001) were observed in those with both LDL-C < 70 mg/dL and Lp(a) <50 mg/dL. On multivariable logistic regression analysis, the coexistence of these 2 lipid controls showed an approximately 70% lower risk (adjusted odds ratio: 0.30; 95% confidence interval: 0.13-0.68) of MaxLCBI4mm ≥400 compared with the reference group (LDL-C ≥ 70 mg/dL and Lp(a) ≥50 mg/dL).

CONCLUSION

Our findings suggest circulating Lp(a) as a potential therapeutic target to stabilize coronary atherosclerosis in CAD patients who achieved LDL-C < 70 mg/dL.

Effect of Alirocumab Added to High-Intensity Statin Therapy on Coronary Atherosclerosis in Patients With Acute Myocardial Infarction: The PACMAN-AMI Randomized Clinical Trial

IMPORTANCE

Coronary plaques that are prone to rupture and cause adverse cardiac events are characterized by large plaque burden, large lipid content, and thin fibrous caps. Statins can halt the progression of coronary atherosclerosis; however, the effect of the proprotein convertase subtilisin kexin type 9 inhibitor alirocumab added to statin therapy on plaque burden and composition remains largely unknown.

OBJECTIVE

To determine the effects of alirocumab on coronary atherosclerosis using serial multimodality intracoronary imaging in patients with acute myocardial infarction.

DESIGN, SETTING, AND PARTICIPANTS

The PACMAN-AMI double-blind, placebo-controlled, randomized clinical trial (enrollment: May 9, 2017, through October 7, 2020; final follow-up: October 13, 2021) enrolled 300 patients undergoing percutaneous coronary intervention for acute myocardial infarction at 9 academic European hospitals.

INTERVENTIONS

Patients were randomized to receive biweekly subcutaneous alirocumab (150 mg; n = 148) or placebo (n = 152), initiated less than 24 hours after urgent percutaneous coronary intervention of the culprit lesion, for 52 weeks in addition to high-intensity statin therapy (rosuvastatin, 20 mg).

MAIN OUTCOMES AND MEASURES

Intravascular ultrasonography (IVUS), near-infrared spectroscopy, and optical coherence tomography were serially performed in the 2 non-infarct-related coronary arteries at baseline and after 52 weeks. The primary efficacy end point was the change in IVUS-derived percent atheroma volume from baseline to week 52. Two powered secondary end points were changes in near-infrared spectroscopy-derived maximum lipid core burden index within 4 mm (higher values indicating greater lipid content) and optical coherence tomography-derived minimal fibrous cap thickness (smaller values indicating thin-capped, vulnerable plaques) from baseline to week 52.

RESULTS

Among 300 randomized patients (mean [SD] age, 58.5 [9.7] years; 56 [18.7%] women; mean [SD] low-density lipoprotein cholesterol level, 152.4 [33.8] mg/dL), 265 (88.3%) underwent serial IVUS imaging in 537 arteries. At 52 weeks, mean change in percent atheroma volume was -2.13% with alirocumab vs -0.92% with placebo (difference, -1.21% [95% CI, -1.78% to -0.65%], P < .001). Mean change in maximum lipid core burden index within 4 mm was -79.42 with alirocumab vs -37.60 with placebo (difference, -41.24 [95% CI, -70.71 to -11.77]; P = .006). Mean change in minimal fibrous cap thickness was 62.67 μm with alirocumab vs 33.19 μm with placebo (difference, 29.65 μm [95% CI, 11.75-47.55]; P = .001). Adverse events occurred in 70.7% of patients treated with alirocumab vs 72.8% of patients receiving placebo.

CONCLUSIONS AND RELEVANCE

Among patients with acute myocardial infarction, the addition of subcutaneous biweekly alirocumab, compared with placebo, to high-intensity statin therapy resulted in significantly greater coronary plaque regression in non-infarct-related arteries after 52 weeks. Further research is needed to understand whether alirocumab improves clinical outcomes in this population.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03067844.