EMD 53998 is a cardiotonic agent that increases myocardial contractility as an inhibitor for phosphodiesterase III (PDE III) and a calcium sensitizer. EMD 53998 increases myocardial contractility, reduces energy consumption and the risk of inducing arrthmias.
References:
[1]. Lues I, et al., The two mechanisms of action of racemic cardiotonic EMD 53998, calcium sensitization and phosphodiesterase inhibition, reside in different enantiomers. J Cardiovasc Pharmacol. 1993 Jun;21(6):883-92.