In the CHOIR study (target Hb, 13.5 g/dL) [14], there were increased incidences of myocardial infarction, hospitalization due to heart failure, and stroke in patients with higher Hb levels; whereas, in the TREAT study (target Hb, ≥ 13.0 g/dL) [15], an increased incidence of cerebral infarction in patients with higher Hb levels was noted. This evidence concerns the gene GSTM1 and heart failure.