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 lesionrelated events occurred in 0%, 5.0%, and 15.9% of patients, respectively (p < 0.0001). Of 105 NC lesionrelated 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).