The patients with more severe heart failure (NYHA class IV) had higher levels of CRP and lower levels of apelin-13 than the patients in NYHA class II (Z = −3.751, p < 0.001 and Z = 3.457, p = 0.002, respectively), and the level of apelin was significantly lower in NYHA class IV than in NYHA class III also (Z = 3.322, p = 0.003). This evidence concerns the gene APLN and heart failure.