The cardiac stimulator (100) has a stimulation unit which is connected with one or multiple stimulation electrodes and is formed to generate a corresponding control signal towards stimulation pulses for the delivery of the stimulation electrode. A control unit is formed to control the stimulation unit in response to the detection of an atrial arrhythmia by a heartbeat detecting unit, such that the subliminal stimulation pulses are delivered for a cardiac contraction modulation therapy.
