Acute coronary syndromes (ACS) remain a major cause of cardiovascular mortality and long-term morbidity worldwide despite substantial advances in revascularization techniques, antithrombotic therapies, and lipid-lowering strategies. Although contemporary management has significantly improved survival, a considerable residual risk of recurrent ischemic events, adverse ventricular remodelling, heart failure, and cardiovascular death persists following ACS. Consequently, accurate risk stratification has become increasingly important to guide individualized secondary prevention and optimize long-term outcomes. Traditional risk assessment after ACS relies largely on clinical characteristics, conventional cardiovascular risk factors, and established risk scores such as GRACE and TIMI. However, growing evidence indicates that several emerging biomarkers and pathophysiological pathways provide additional prognostic information beyond conventional models. These markers reflect distinct biological processes including residual inflammatory activity, myocardial injury and remodelling, renal dysfunction, metabolic impairment, and visceral adiposity. This review summarizes current evidence regarding both established and emerging prognostic markers after ACS across six major pathophysiological domains: lipid abnormalities and traditional cardiovascular risk factors; systemic inflammation and residual inflammatory risk; myocardial injury and adverse ventricular remodelling; cardiorenal dysfunction; visceral adiposity; and anti-inflammatory therapeutic strategies. For each domain, we discuss underlying biological mechanisms, key findings from major clinical trials and registries, and the potential incremental value of biomarkers in contemporary risk stratification. Collectively, these markers support a multidimensional approach to post-ACS risk assessment and may contribute to more personalized therapeutic strategies aimed at reducing residual cardiovascular risk.