The Relationship Between Serum Amyloid A Protein and Short-Term Adverse Cardiovascular Outcomes in Older Patients with STEMI: A Prospective Study

Background Despite improved treatments for myocardial infarction (MI), residual risk persists in older patients, mainly attributed to age- associated comorbidities and inflammation. Serum amyloid A (SAA) lacks sufficient evidence for predicting short-term clinical endpoints in older patients with ST-segment elevation MI (STEMI). Methods We prospectively enrolled 327 older patients (≥ 60 years) with STEMI individuals treated with primary percutaneous coronary intervention and 327 healthy controls (HCs). SAA levels were measured at admission. The Global Registry of Acute Coronary Events score, Thrombolysis in Myocardial Infarction risk score, and frailty index were assessed. The primary endpoint was 30-day major adverse cardiovascular events (MACE), defined as cardiac death, heart failure (HF), and cardiogenic shock (CS). Results The serum SAA levels in older STEMI patients were significantly higher than those in the HC group ([735.94 ± 506.60] ng/mL vs. [427.58 ± 273.70] ng/mL, P<0.001). Moreover, the SAA expression was further remarkably elevated in patients with 30-day heart failure (HF), cardiogenic shock (CS) or cardiac death events (all P<0.001). After adjusting for risk scores, traditional biomarkers, and clinical variables, higher SAA levels independently predicted HF events (all adjusted P < 0.01) and CS and/or cardiac death (all adjusted P < 0.01). The inclusion of SAA in an established risk factor models significantly enhanced C-statistics, net reclassification, and integrated discrimination. SAA strongly predicted HF in non-frail patients (hazard ratio [HR] = 5.477, P < 0.001), but not in frail patients (HR = 1.558, P = 0.104), with a significant interaction (P = 0.019). Conclusions SAA is an independent predictor of 30-day MACE in older patients with STEMI and enhances traditional risk assessment, especially in non-frail individuals. Trial registration: ClinicalTrails.gov registration no. NCT03752515