Two-year plaque level outcomes involving the left anterior descending artery: insights from the Lipid-Rich Plaque study
Authors: Kuku K O , Garcia-Garcia H M , Doros G , Mintz G S , Ali Z A , Singh S , Cate T T , Powers E R , Wong S C , Wykrzykowska J , Shah P R , Sum S T , Torguson R , Di Mario C , Waksman R ,   LRP Study Group
Published: October 2021

Abstract

Background
Coronary artery disease (CAD) is more frequently seen in the left anterior descending artery (LAD). LAD disease resulting in an acute anterior wall myocardial infarction (MI) is associated with a low left ventricular ejection fraction and invariably a worsened prognosis. The Lipid Rich Plaque (LRP) Study reported the strong association between NIRS-IVUS derived max4mmLCBI and future plaque events in non-culprit vessels.

Objective
To report the events involving the LAD versus the other major coronary vessels in the Lipid-Rich Plaque study.

Methods
The LRP Study was an international, multicenter, prospective cohort study conducted in patients with suspected CAD who underwent cardiac catheterization with possible ad hoc percutaneous coronary intervention (PCI) for an index event. Plaque level events within the subsequent 2 years were adjudicated. Plaque level events were defined as the composite of cardiac death, cardiac arrest, non-fatal MI, acute coronary syndrome (ACS), revascularization by coronary artery bypass grafting (CABG) or PCI, and rehospitalization for angina with &gt;20% stenosis progression related and unrelated to the treatment at index procedure. All together these events were reported as Non-Culprit Lesion-related Major Adverse Cardiac Events (NC-MACE). Prespecified subgroups of segments were defined according to LAD (vs. non-LAD) with maxLCBI4mm ≤400 or &gt;400.

Results
A total of 57 plaque events occurred through 2 years of follow-up. More than half occurred in the LAD, followed by the LCX and the RCA. There were more, albeit non-statistically significant, lipid-rich plaques in the LAD, compared to the LCX and RCA: 12.5% vs 10.4% and 11.3%, respectively, p=0.097. A minimum lumen area (MLA) ≤4mm2 within the maxLCBI4mm was observed more in the LAD and the LCX, compared to the RCA: 34.1% vs 25.9% vs 13.7%, respectively, p&lt;0.001. Lipid rich plaque (maxLCBI4mm&gt;400) was present in 20/57 (35.1%) of the plaque level events, a large PB (≥70%) was present in 6/57 (10.5%), and a small MLA (≤4mm2) was present in 26/57 (45.6%). Out of the 57 plaque level events, 4 (7%) had all three high risk plaque characteristics.
Presence of an elevated maxLCBI4mm (&gt;400) was predictive of NC-MACE in all subgroups (for LAD &gt;400 HR 4.32; 95% CI (1.93, 9.69; p 0.0004) and for the non-LAD &gt;400 HR 2.56; 95% CI (1.06, 6.17; p 0.0354).

Conclusion
Non-culprit segments in the LAD with maxLCBI4mm values &gt;400 were more frequently associated with plaque level events than in the lipid -rich segments in the other epicardial vessels. This sub-study results point to the unequivocal value of maxLCBI4mm&gt;400 in predicting future plaque level events especially in the LAD.

Funding Acknowledgement
Type of funding sources: Private company. Main funding source(s): Infraredx Plaque Events-Ware Segment Locations