The acute inotropic effects of cardiac contractility modulation (CCM) are associated with action potential duration shortening and mediated by β1-adrenoceptor signalling

► CCM induced responses are related to the amplitude and duration of the stimulus. ► CCM causes a shortening of ventricular monophasic action potential duration. ► Inotropic and electrophysiological responses to CCM are β1-adrenoceptor dependent. ► CCM signal application stimulates catecholamine release. ► Action potential shortening with CCM is partially mediated via IKs.