To Örebro University

Background: In PROSPECT II, 182 patients with plaque burden (PB) ≥ 65% were randomized to bioresorbable vascular scaffold (BVS) + guideline-directed medical therapy (GDMT) versus GDMT alone. Protocol-directed 3-vessel near-infrared spectroscopy (NIRS)-IVUS was repeated at 25 months.

Methods: Excluding lesions treated by BVS, paired (baseline and follow-up) NIRS-IVUS was available in 626 nonculprit lesions in 165 patients. Follow-up minimum lumen area (MLA) and the corresponding baseline sites were measured: rapid lesion progression (RLP) was a ≥ 0.5 mm2 decrease of MLA, and rapid lesion regression (RLR) was a ≥ 0.5 mm2 increase of MLA.

Results: RLP occurred in 34.5%, RLR occurred in 15.5%, and 49.8% had “no change.” The % change in vessel area correlated with the % change of plaque area (r = 0.81, P < 0.001), demonstrating vessel remodeling (Figure 1). At baseline, the RLP lesions had larger plaque areas, longer lesions, and higher prevalence of lipid-rich plaque (maxLCBI4mm ≥ 324.7). During follow-up, 80.2% of RLP lesions had negative remodeling irrespective of the change in plaque area, whereas 76.3% of RLR lesions had a decrease in plaque area irrespective of negative or positive remodeling. In lesions without change in lumen area, there were compensatory changes in plaque and vessel areas.

Conclusion: In stabilized patients post-MI treated with GDMT, half of untreated non–flow- limiting lesions had significant lumen changes at 25 months, with RLP twice as frequent as RLR. The predominant mechanism of RLP was negative vessel remodeling whereas the predominant mechanism of RLR was reduction in plaque area.