Patent ID: 6912421

Claim:
An active implantable medical device, in particular a pacemaker, defibrillator, cardiovertor or a multisite device, comprising: means for detecting atrial events; means for detecting ventricular events; means for delivering an atrial stimulation; means for delivering a ventricular stimulation, said means being able to deliver a ventricular stimulation pulse (V) after a programmed atrio-ventricular delay (AVD) following a detected atrial event and in the absence of detected ventricular event within said AVD; and means for detecting a fusion situation, said fusion situation detecting means being able to: analyze a sequence of successive cardiac cycles by modifying the AVD from a first cardiac cycle to a following cardiac cycle, and detect the presence or the absence of a spontaneous ventricular event occurring inside the modified AVD; and means for determining an existence of a risk of fusion response to a detected spontaneous ventricular event during at least one of the cardiac cycles of the sequence.