MPO and heart failure: In addition to its relevance in the aetiology of t‐AL, MPO has become an important target for novel anti‐inflammatory drug development [23] and a number of potent specific MPO inhibitors have recently been reported, including PF1355 [24, 25], MPOi‐II [32] and AZD4831 the latter of which is currently in early clinical trials in patients with heart failure [37, 38].