To evaluate the biological activity of TIMP3 as a heart failure target, we characterized N‐TIMP3 (N‐domain, 13.9 kDa), TIMP3v2 (K22S/F34N), 5xGlyco‐TIMP3 (v82), and v82 with Fc fused in the C‐terminus (v82‐Fc). This evidence concerns the gene TIMP3 and heart failure.