Combined effect of inflammation and malnutrition for long-term prognosis in patients with acute coronary syndrome undergoing percutaneous coronary intervention: a cohort study

Background Inflammation is a key driver of atherosclerotic diseases and is often accompanied by disease-related malnutrition. However, the long-term burden of dysregulated inflammation with superimposed undernutrition in patients with acute coronary syndrome (ACS) remains unclear. This study sought to investigate the double burden and interplay of inflammation and malnutrition in patients with ACS undergoing percutaneous Coronary Intervention (PCI). Methods We retrospectively included 1,743 ACS patients undergoing PCI from June 2016 through November 2017 and grouped them according to their baseline nutritional and inflammatory status. Malnutrition was determined using the nutritional risk index (NRI) with a score lower than 100 and a high-inflamed condition defined as hs-CRP over 2 mg/L. The primary outcome was major adverse cardiovascular events (MACEs), compositing of cardiac mortality, non-fatal myocardial infarction, non-fatal stroke, and unplanned revascularization. Long-term outcomes were examined using the Kaplan-Meier method and compared with the log-rank test. Multivariable Cox proportional hazards regression analysis was applied to adjust for confounding. The reclassification index (NRI)/integrated discrimination index (IDI) statistics estimated the incremental prognostic impact of NRI and hs-CRP in addition to the Global Registry of Acute Coronary Events (GRACE) risk score. Results During a median follow-up of 30 months (ranges 30-36 months), 351 (20.1%) MACEs occurred. Compared with the nourished and uninflamed group, the malnourished and high-inflamed group displayed a significantly increased risk of MACEs with an adjusted hazard ratio of 2.446 (95% CI: 1.464-4.089; P < 0.001). The prognostic implications of NRI were influenced by patients' baseline inflammatory status, as it was only associated with MACEs among those high-inflamed (P for interaction = 0.005). Incorporating NRI and hs-CRP into the GRACE risk score significantly improved its predictive ability for MACEs (NRI: 0.210, P < 0.001; integrated discrimination index; IDI: 0.010, P < 0.001) and cardiac death (NRI: 0.666, P < 0.001; IDI: 0.023, P = 0.002). Conclusions Among patients with ACS undergoing PCI, the double burden of inflammation and malnutrition signifies poorer outcomes. Their prognostic implications may be amplified by each other and jointly improve the GRACE risk score's risk prediction performance.