MMP2 and heart failure: These substances can be divided into groups associated with 1) nitric oxide (NO): nitrite/nitrate and asymmetric dimethylarginine (ADMA); 2) oxidative stress: malondialdehyde (MDA), 8-hydroxy-2-deoxyguanosine (8-OHdG), the ferric-reducing ability of plasma (FRAP), cysteine, homocysteine, cysteinylglycine and glutathione; 3) the metabolism of extracellular matrix: matrix metalloproteinase 2 and 9 (MMP2, MMP9) and tissue inhibitors of metalloproteinases 1 (TIMP1); 4) renal functions: cystatin C; and 5) heart failure: B type natriuretic peptide (BNP) and NT-proBNP.