Sensing ventricular noise artifacts in an active implantable medical device for pacing, resynchronization and/or defibrillation of the heart. This device concerns sensing heart rhythm through an endocardial electrode collecting the depolarization potentials, and detecting the myocardium contractions through an endocardial acceleration sensor. The device searches for ventricular noise artifacts (X, Y) by correlating the signals representative of successive ventricular and atrial depolarizations (P, R) with the signals representative of successive acceleration peaks (PEA I). In case of a lack of correlation, a signal of suspicion of ventricular noise is delivered, which temporarily modifies the sensing sensitivity (S) of the sensing circuit.