Abstract Background The majority of NSTEMI burden resides outside high-income countries (HICs). We describe presentation, care, and outcomes of NSTEMI by country income classification. Methods and results Prospective cohort study including 2947 patients with NSTEMI from 287 centres in 59 countries, stratified by World Bank country income classification. Quality of care was evaluated based on 12 guideline-recommended care interventions. The all-or-none scoring composite performance measure was used to define receipt of optimal care. Outcomes included in-hospital acute heart failure, stroke/transient ischaemic attack, and death, and 30-day mortality. Patients admitted with NSTEMI in low to lower-middle-income countries (LLMICs), compared with patients in HICs, were younger, more commonly diabetic, and current smokers, but with a lower burden of other comorbidities, and 76.7% met very high risk criteria for an immediate invasive strategy. Invasive coronary angiography use increased with ascending income classification (LLMICs, 79.2%; upper middle income countries [UMICs], 83.7%; HICs, 91.0%), but overall care quality did not (≥80% of eligible interventions achieved: LLMICS, 64.8%; UMICs 69.6%; HICs 55.1%). Rates of acute heart failure (LLMICS, 21.3%; UMICs, 12.1%; HICs, 6.8%; P < 0.001), stroke/transient ischaemic attack (LLMICS: 2.5%; UMICs: 1.5%; HICs: 0.9%; P = 0.04), in-hospital mortality (LLMICS, 3.6%; UMICs: 2.8%; HICs: 1.0%; P < 0.001) and 30-day mortality (LLMICs, 4.9%; UMICs, 3.9%; HICs, 1.5%; P < 0.001) exhibited an inverse economic gradient. Conclusion Patients with NSTEMI in LLMICs present with fewer comorbidities but a more advanced stage of acute disease, and have worse outcomes compared with HICs. A cardiovascular health narrative is needed to address this inequity across economic boundaries.