The natural course of nonculprit coronary artery lesions; analysis by serial quantitative coronary angiography

BACKGROUND: Nonculprit lesions are the major cause of future cardiovascular events. However, the natural course of nonculprit lesions and angiographic predictors of plaque progression are not well-studied. The purpose of our study was to observe the natural course of nonculprit lesions, and to identify predictors of unanticipated future events and angiographic progression in nonculprit lesions. METHODS: We analyzed 640 nonculprit lesions with a length of ≥2 mm and luminal narrowing ≥30% from 320 patients who had two serial angiographic follow-ups; 9 to 13 months post-PCI and 24 months post-PCI. The study endpoints were nonculprit-ischemia driven revascularization (IDR) and the rate of diameter stenosis (DS) progression. Those with progression of DS > 12%/year were defined as 'rapid progressors'. RESULTS: During the median follow-up period of 737 days, 20 lesions in 20 patients (6.3%) required nonculprit-IDR. Independent predictors of nonculprit-IDR were diabetes (hazard ratio [HR] 2.93, 95% confidence interval [CI] 1.072-8.007, p = 0.036) and lesion type B2/C (HR 4.017, 95% CI 1.614-9.997, p = 0.003). The presence of one or both of the two major risk factors was associated with significant DS progression (3.0 ± 6.8% vs. 3.5 ± 6.1% vs. 6.8 ± 9.9% for lesions with 0, 1 and both risk factors, p < 0.001). Among the 640 lesions, 38 lesions (5.9%) in 33 patients were rapid progressors, while risk factors of rapid progressors included lesion type B2/C as a lesion-related risk factor (HR 1.998, 95% CI 1.006-3.791, p = 0.048) and diabetes mellitus as a patient-related risk factor (HR 3.725, 95% CI 1.937-7.538, p < 0.001). Lesions with both risk factors (type B2/C lesions in diabetic patients) were at the highest risk of rapid progression (odds ratio 3.250, 95% CI 1.451-7.282), compared to type A/B1 lesions in non-diabetic patients. CONCLUSION: Nonculprit-IDR was not uncommon during the 2-year follow up period in our population. The major risk factors of nonculprit lesion progression were diabetes and lesion type B2/C. TRIAL REGISTRATION: Retrospectively registered and approved by the institutional review board of Seoul National University Hospital (No.: 1801-138-918) on February 2nd, 2018.