Discrimination of noxious and non noxious ventricular extrasystoles in an active implantable medical device such as a cardiac pacemaker, defibrillator, cardiovertor and/or multisite device

An active implantable medical device comprising:

• means for sensing ventricular and atrial cardiac activity,
• analyzing means for discriminating a ventricular extrasystole from said sensed ventricular cardiac activity, and for detecting in the sensed cardiac activity an occurrence of a cardiac cycle,
• measuring means for delivering an intracardiac impedance signal measured between two cavities of the heart correlated to the instantaneous blood flow, and
• discriminating means for detecting variations in the delivered impedance signal measured between two cavities of the heart, determining, in response to a detected variation, a presence or an absence of a significant mechanical activity of the myocardium consecutive to a discriminated ventricular extrasystole, and determining a noxious character of the ventricular extrasystole in response to a determined absence of significant mechanical activity and a non noxious character of the ventricular extrasystole in response to a determined presence of significant mechanical activity, wherein the discriminating means further comprises means for evaluating an increase in the intracardiac impedance measured between two cavities of the heart after the occurrence of the detected ventricular extrasystole, comparing said increased intracardiac impedance measured between two cavities of the heart to a predetermined threshold, and determining a presence of a significant mechanical activity of the myocardium in response to said increase crossing said threshold.