An implantable system configured to terminate a pacemaker mediated tachycardia, the implantable system comprising: an atrial leadless pacemaker (aLP) configured to be implanted in or on an atrial cardiac chamber, the aLP including at least one processor and including at least two electrodes that can be used for sensing an intrinsic atrial event and pacing the atrial cardiac chamber; a ventricular leadless pacemaker (vLP) configured to be implanted in or on a ventricular cardiac chamber, the vLP including at least one processor and including at least two electrodes that can be used for sensing an intrinsic ventricular event, pacing the ventricular cardiac chamber, and performing i2i communication; wherein during a period that the PMT is not detected, the aLP is configured to deliver an atrial pacing pulse to the atrial cardiac chamber in response to a PA interval expiring without an intrinsic atrial event being detected during the PA interval, characterized in that at least one of the aLP or the vLP configured to detect a PMT, and in response thereto, inform the other one of the aLP or the vLP, via an i2i communication, that the PMT was detected; the aLP configured to initiate a PMT PA interval, in response to the PMT being detected, wherein the PMT PA interval is shorter than a PA interval that the aLP would otherwise use for atrial pacing if a PMT was not detected; and the vLP configured to initiate a PMT PV interval, in response to the PMT being detected, wherein the PMT PV interval is longer than the PMT PA interval; wherein the PA interval specifies when an atrial pacing pulse should be delivered by the aLP to the atrial cardiac chamber following an intrinsic atrial sensed event, in response to the PA interval expiring without another intrinsic atrial event being detected during the PA interval, during a period that the PMT has not been detected; wherein the PMT PA interval specifies when an atrial pacing pulse should be delivered by the aLP to the atrial cardiac chamber following an intrinsic atrial sensed event, in response to the PMT PA interval expiring without another intrinsic atrial event being detected during the PMT PA interval, during a period that the PMT has been detected; and wherein the PMT PV interval specifies when a ventricular pacing pulse should be delivered by the vLP to the ventricular cardiac chamber following an intrinsic atrial sensed event, in response to the PMT PV interval expiring without an intrinsic ventricular event being detected during the PMT PV interval, during a period that the PMT has been detected. an atrial leadless pacemaker (aLP) configured to be implanted in or on an atrial cardiac chamber, the aLP including at least one processor and including at least two electrodes that can be used for sensing an intrinsic atrial event and pacing the atrial cardiac chamber; a ventricular leadless pacemaker (vLP) configured to be implanted in or on a ventricular cardiac chamber, the vLP including at least one processor and including at least two electrodes that can be used for sensing an intrinsic ventricular event, pacing the ventricular cardiac chamber, and performing i2i communication; wherein during a period that the PMT is not detected, the aLP is configured to deliver an atrial pacing pulse to the atrial cardiac chamber in response to a PA interval expiring without an intrinsic atrial event being detected during the PA interval, characterized in that at least one of the aLP or the vLP configured to detect a PMT, and in response thereto, inform the other one of the aLP or the vLP, via an i2i communication, that the PMT was detected; the aLP configured to initiate a PMT PA interval, in response to the PMT being detected, wherein the PMT PA interval is shorter than a PA interval that the aLP would otherwise use for atrial pacing if a PMT was not detected; and the vLP configured to initiate a PMT PV interval, in response to the PMT being detected, wherein the PMT PV interval is longer than the PMT PA interval; wherein the PA interval specifies when an atrial pacing pulse should be delivered by the aLP to the atrial cardiac chamber following an intrinsic atrial sensed event, in response to the PA interval expiring without another intrinsic atrial event being detected during the PA interval, during a period that the PMT has not been detected; wherein the PMT PA interval specifies when an atrial pacing pulse should be delivered by the aLP to the atrial cardiac chamber following an intrinsic atrial sensed event, in response to the PMT PA interval expiring without another intrinsic atrial event being detected during the PMT PA interval, during a period that the PMT has been detected; and wherein the PMT PV interval specifies when a ventricular pacing pulse should be delivered by the vLP to the ventricular cardiac chamber following an intrinsic atrial sensed event, in response to the PMT PV interval expiring without an intrinsic ventricular event being detected during the PMT PV interval, during a period that the PMT has been detected.