The present invention relates to a cardiac pacemaking system (1), comprising: an implantable leadless pacemaker (10) that is configured to be implanted into a chamber of a patients heart (2), and an implantable subcutaneous cardioverter-defibrillator (20), wherein the leadless pacemaker (10) is configured to apply electrical pacing pulses to the heart (2), particularly in order to provide antibradycardia pacing, and wherein the subcutaneous cardioverter-defibrillator (20) is configured to apply electrical stimulation to the heart (2) for providing defibrillation of the heart (2), and wherein the leadless pacemaker (10) is configured to sense the patients heart rhythm, and wherein the cardiac pacemaking system (1) comprises a communication link (101) between the leadless pacemaker (10) and the subcutaneous cardioverter-defibrillator (20), wherein the leadless pacemaker (10) is configured to send an output signal to the subcutaneous cardioverter-defibrillator (20) via said communication link (101) in an unidirectional fashion when the leadless pacemaker (10) detects a heart rhythm that requires said electrical stimulation of the subcutaneous cardioverter-defibrillator (20), and wherein the subcutaneous cardioverter-defibrillator (20) is configured to apply said electrical stimulation to the heart (2) when the subcutaneous cardioverter-defibrillator (20) receives said output signal.
