BackgroundThe potential predictive significance of atherogenic index of plasma (AIP) for cardiovascular outcomes in patients with acute coronary syndrome (ACS) and who have undergone percutaneous coronary intervention (PCI), with low-density lipoprotein-cholesterol (LDL-C) below 1.8mmol/L, has not been well explored.MethodsThe retrospective cohort analysis included 1,133 patients with ACS and LDL-C levels below 1.8mmol/L who underwent PCI. AIP is calculated as log (triglyceride/high-density lipoprotein-cholesterol). Patients were divided into two groups according to the median value of AIP. The primary endpoint was major adverse cardiovascular and cerebrovascular events (MACCEs), a composite of all-cause death, nonfatal myocardial infarction, ischemic stroke or unplanned repeat revascularization. The association between AIP and the prevalence of MACCE was evaluated using multivariable Cox proportional hazard models.ResultsOver a median follow-up of 26 months, the incidence of MACCE was higher in the high AIP group compared to the low AIP group (9.6% vs. 6.0%,Plog-rank = 0.020), and the difference was mainly derived from an increased risk of unplanned repeat revascularization (7.6% vs. 4.6%, P log-rank = 0.028). After adjusting for multiple variables, elevated AIP was independently associated with an increased risk of MACCE, regardless of whether AIP was considered a nominal or continuous variable (hazard ratio [HR] 1.62, 95% confidence interval [CI] 1.04–2.53 or HR 2.01, 95% CI 1.09–3.73).ConclusionsThe present study demonstrates that AIP is a significant predictor of adverse outcomes in ACS patients undergoing PCI with LDL-C < 1.8mmol/L. These results suggest that AIP may offer supplementary prognostic information for ACS patients with optimally managed LDL-C levels.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12933-023-01888-3.