An implantable stimulation device delivers a stimulation pulse in the ventricular chamber of a patient's heart and automatically adjusts a post-ventricular atrial blanking period. The stimulation device generates a ventricular stimulation pulse to trigger an evoked response, in order to produce a ventricular far-field signal that follows a successfully captured ventricular stimulation pulse. The stimulation device further includes an atrial sense circuit that senses the ventricular far-field signal, and a control system that adaptively segments the post-ventricular atrial blanking period in a post-ventricular atrial blanking period (PVAB) which is fixed in duration, and a variable far-field interval (FFI) window. PVAB is initiated upon the delivery of the ventricular stimulation pulse, such that events sensed outside the segmented post-ventricular atrial blanking (SPVAB) period are presumed to be intrinsic atrial events, and events sensed within the far-field interval window are presumed to be far-field signals. The far-field interval window is preferably centered on a previously sensed far-field R-wave. If an intrinsic ventricular event is sensed, the stimulation device does not initiate the PVAB period but rather sets the FFI window.