B2M and acute coronary syndrome: Overall, our paper adds to the expanding literature, showing that plasma levels of middle molecules in general and B2M in particular [19,21,23] can predict the regulatory relevant threshold of RRF >2 mL/min on a par with the performance of the clinically accepted, validated troponin assays in the diagnosis of acute coronary syndromes (AUC: 0.84–0.94) [65].