Nonculprit Vulnerable Plaques and Prognosis in Myocardial Infarction With Versus Without ST-Segment Elevation: A PROSPECT II Substudy.

Abstract

BACKGROUND Clinical guidelines recommend different revascularization strategies for nonculprit lesions in patients with ST-segment-elevation myocardial infarction (STEMI) versus non-STEMI (NSTEMI). Whether the prevalence of untreated high-risk vulnerable plaques differs in STEMI and NSTEMI and affects their outcomes is unknown. METHODS In PROSPECT II (Providing Regional Observations to Study Predictors of Events in the Coronary Tree II), a multicenter, prospective natural history study, patients with recent myocardial infarction underwent 3-vessel coronary angiography with coregistered near-infrared spectroscopy and intravascular ultrasound after successful percutaneous coronary intervention of obstructive lesions from 2014 through 2017. Two-feature high-risk plaques were defined as those with both plaque burden ≥70% and maximum lipid core burden index over any 4-mm segment ≥324.7. The primary end point was major adverse cardiovascular events arising from untreated nonculprit lesions during a median 3.7-year follow-up. RESULTS Of 898 patients, 199 (22.2%) with 849 nonculprit lesions had STEMI and 699 (77.8%) with 2784 nonculprit lesions had NSTEMI. By intravascular ultrasound, the median nonculprit lesion length was 17.4 mm (interquartile range, 16.3-18.5) in STEMI and 17.7 mm (interquartile range, 17.1-18.4) in NSTEMI (P=0.63), and the median minimal lumen area was 5.5 mm2 (interquartile range, 5.3-5.7 mm2) in STEMI and 5.5 mm2 (interquartile range, 5.3-5.6 mm2) in NSTEMI (P=0.99). At the lesion level, the prevalence of 2-feature high-risk nonobstructive nonculprit plaques was slightly higher in patients with STEMI than in patients with NSTEMI (12.8% versus 10.1%; P=0.03). At the patient level, however, the prevalence of 2-feature high-risk plaques was similar in STEMI versus NSTEMI (38.8% versus 32.7%; P=0.11). The prevalence of patients with 1 or more lesions meeting at least 1 high-risk plaque criterion was also similar (plaque burden ≥70%, 63.3% versus 57.8% [P=0.16]; maximum lipid core burden index over any 4-mm segment ≥324.7, 63.3% versus 57.6% [P=0.15]). The 4-year rates of nonculprit lesion-related major adverse cardiovascular events were similar in STEMI versus NSTEMI (8.6% versus 7.8%; hazard ratio, 1.02 [95% CI, 0.57-1.81]; P=0.95), as were the rates of all major adverse cardiovascular events (14.2% versus 13.0%; hazard ratio, 1.06 [95% CI, 0.68-1.64]; P=0.80). CONCLUSIONS In the PROSPECT II study, the per-patient prevalence of high-risk vulnerable plaques was comparable in STEMI versus NSTEMI, as was the overall long-term incidence of nonculprit lesion-related and all major adverse cardiovascular events. These results support a similar revascularization strategy for nonculprit lesions in patients with STEMI or NSTEMI after culprit lesion management. REGISTRATION URL: https://www.clinicaltrials.gov; Unique identifier: NCT02171065.