Characteristics and Clinical Significance of Angiographically Mild Lesions in Acute Coronary Syndromes

Objectives The aim of this study was to assess whether residual nonculprit (NC) lesions, defined as visual diameter stenosis ≥30% after successful percutaneous coronary intervention, affect the rate of future events in patients with acute coronary syndromes. Background In patients with acute coronary syndromes, approximately one-half of recurrent events after percutaneous coronary intervention arise from untreated lesions. Methods Patients enrolled in PROSPECT (Providing Regional Observations to Study Predictors of Events in the Coronary Tree) were divided into 3 groups: those with no NC lesions, 1 NC lesion, or ≥2 NC lesions. Time to events for major adverse cardiac events was estimated up to 3 years. Results Among 697 patients, 13.3% had no NC lesions, 19.7% had 1 NC lesion, and 67.0% had ≥2 NC lesions. The median diameter stenoses of the NC lesions in the latter 2 groups were 36.7% (interquartile range: 31.0% to 43.4%) and 37.4% (interquartile range: 32.0% to 46.5%), respectively (p = 0.22). At least 1 thin-cap fibroatheroma was present in one-half the patients in each group. At 3 years, the incidence of major adverse cardiac events was 8.5%, 15.2%, and 24.3%, respectively (p = 0.0009). NC lesion–related events occurred in 0%, 5.0%, and 15.9% of patients, respectively (p < 0.0001). Of 105 NC lesion–related clinical events occurring during follow-up, 73 (69.5%) originated from angiographically evident baseline NC lesions (of which 36 had diameter stenosis >50%), while the other 32 arose from normal or near normal segments. Conclusions Residual NC lesions are common after percutaneous coronary intervention for acute coronary syndromes and portend a higher rate of recurrent ischemic events within 3 years, especially when angiographically more severe. Conversely, the absence of NC lesions by angiography is highly predictive of freedom from events not related to the originally treated culprit lesion(s).