An autonomous cardiac implant of the leadless capsule type, having an implant body provided with means for anchoring to a cardiac wall, the implant body accommodating an electronic unit and an energy harvesting module with an energy storage component for powering the electronic unit, the energy harvesting module being adapted to convert into electrical energy external stresses applied to the implant body under the effect of movements of a wall to which the implant is anchored and/or of blood flow rate variations in the environment surrounding the implant at the rhythm of heartbeats and/or of cardiac tissue vibrations, wherein the energy harvesting module comprises: - an inertial unit (24, 28) subjected to said external stresses; - a translator adapted to convert the mechanical energy produced by the oscillations of the inertial unit into an oscillating electrical signal; and - a power management circuit, adapted to rectify and regulate said oscillating electrical signal, to output a stabilized direct voltage or current for powering said electronic unit and/or for charging said energy storage component, the implant further comprising an analysis module receiving as an input the electrical signal provided by the translator and adapted to analyze variations of this oscillating electrical signal to derive therefrom a value of a physiological parameter of the patient with the implant, characterized in that it further comprises: - a sequencing module, comprising: a circuit for detecting successive ventricular or atrial cardiac events; and a windowing circuit, adapted to define at least one predetermined time window (F1, F2, F3) between two consecutive detected cardiac events; and in that the analysis module is a module adapted to: analyze the instantaneous variations of said oscillating electrical signal inside said at least one predetermined time window (F1, F2, F3) so defined between two consecutive detected cardiac events, and derive therefrom a current value i) of at least one physiological parameter, and/or ii) at least one physical activity parameter, of the patient with the implant. the energy harvesting module being adapted to convert into electrical energy external stresses applied to the implant body under the effect of movements of a wall to which the implant is anchored and/or of blood flow rate variations in the environment surrounding the implant at the rhythm of heartbeats and/or of cardiac tissue vibrations, wherein the energy harvesting module comprises: - an inertial unit (24, 28) subjected to said external stresses; - a translator adapted to convert the mechanical energy produced by the oscillations of the inertial unit into an oscillating electrical signal; and - a power management circuit, adapted to rectify and regulate said oscillating electrical signal, to output a stabilized direct voltage or current for powering said electronic unit and/or for charging said energy storage component, - an inertial unit (24, 28) subjected to said external stresses; - a translator adapted to convert the mechanical energy produced by the oscillations of the inertial unit into an oscillating electrical signal; and - a power management circuit, adapted to rectify and regulate said oscillating electrical signal, to output a stabilized direct voltage or current for powering said electronic unit and/or for charging said energy storage component, the implant further comprising an analysis module receiving as an input the electrical signal provided by the translator and adapted to analyze variations of this oscillating electrical signal to derive therefrom a value of a physiological parameter of the patient with the implant, characterized in that it further comprises: - a sequencing module, comprising: a circuit for detecting successive ventricular or atrial cardiac events; and a windowing circuit, adapted to define at least one predetermined time window (F1, F2, F3) between two consecutive detected cardiac events; - a sequencing module, comprising: a circuit for detecting successive ventricular or atrial cardiac events; and a windowing circuit, adapted to define at least one predetermined time window (F1, F2, F3) between two consecutive detected cardiac events; a circuit for detecting successive ventricular or atrial cardiac events; and a windowing circuit, adapted to define at least one predetermined time window (F1, F2, F3) between two consecutive detected cardiac events; and in that the analysis module is a module adapted to: analyze the instantaneous variations of said oscillating electrical signal inside said at least one predetermined time window (F1, F2, F3) so defined between two consecutive detected cardiac events, and derive therefrom a current value i) of at least one physiological parameter, and/or ii) at least one physical activity parameter, of the patient with the implant. analyze the instantaneous variations of said oscillating electrical signal inside said at least one predetermined time window (F1, F2, F3) so defined between two consecutive detected cardiac events, and derive therefrom a current value i) of at least one physiological parameter, and/or ii) at least one physical activity parameter, of the patient with the implant.