A method of communication in a system comprising a plurality of implantable medical devices, wherein a first device comprises at least a means for detecting a signal that is representative of atrial activity, a transmitting means, and a controller configured to analyze a signal that is representative of the atrial activity, and a second device, which is independent of the first implantable medical device, comprising at least a receiving means and a controller, the method comprising: A) a step of time synchronization of the first device with the second device, by sending a synchronization signal from the transmitting means of the first device to the second device, the synchronization signal being sent following an identification, by means of the controller of the first device, of a predefined electrical wave of the PQRS complex of a signal representative of the atrial activity; B) a step of determination of the duration of a cardiac cycle, the steps A and B being followed: C) by a step of determination of a synchronization interval (108, 208), the duration of the synchronization interval being determined based on the duration of the cardiac cycle so as to be shorter than the duration of the cardiac cycle, and the start of the synchronization interval (108, 208) being determined based on the synchronization signal, D) by a step of activation of the receiving means of the second device during the synchronization interval (108, 208), the receiving means of the second device being deactivated outside of the synchronization interval (108, 208) by the controller of the second device. wherein a first device comprises at least a means for detecting a signal that is representative of atrial activity, a transmitting means, and a controller configured to analyze a signal that is representative of the atrial activity, and a second device, which is independent of the first implantable medical device, comprising at least a receiving means and a controller, the method comprising: A) a step of time synchronization of the first device with the second device, by sending a synchronization signal from the transmitting means of the first device to the second device, the synchronization signal being sent following an identification, by means of the controller of the first device, of a predefined electrical wave of the PQRS complex of a signal representative of the atrial activity; B) a step of determination of the duration of a cardiac cycle, A) a step of time synchronization of the first device with the second device, by sending a synchronization signal from the transmitting means of the first device to the second device, the synchronization signal being sent following an identification, by means of the controller of the first device, of a predefined electrical wave of the PQRS complex of a signal representative of the atrial activity; by sending a synchronization signal from the transmitting means of the first device to the second device, the synchronization signal being sent following an identification, by means of the controller of the first device, of a predefined electrical wave of the PQRS complex of a signal representative of the atrial activity; B) a step of determination of the duration of a cardiac cycle, the steps A and B being followed: C) by a step of determination of a synchronization interval (108, 208), the duration of the synchronization interval being determined based on the duration of the cardiac cycle so as to be shorter than the duration of the cardiac cycle, and the start of the synchronization interval (108, 208) being determined based on the synchronization signal, D) by a step of activation of the receiving means of the second device during the synchronization interval (108, 208), C) by a step of determination of a synchronization interval (108, 208), the duration of the synchronization interval being determined based on the duration of the cardiac cycle so as to be shorter than the duration of the cardiac cycle, and the start of the synchronization interval (108, 208) being determined based on the synchronization signal, D) by a step of activation of the receiving means of the second device during the synchronization interval (108, 208), the receiving means of the second device being deactivated outside of the synchronization interval (108, 208) by the controller of the second device.