1. A heart stimulating system for stimulating at least a ventricle of a heart comprising: a stimulation pulse generator configured to generate electric stimulation pulses and being connected or being connectable to at least a ventricular stimulation electrode configured to deliver electric stimulation pulses to at least a ventricle of a heart; an atrial sensing stage connected or being connectable to an electrode configured to pick up electric potentials inside at least an atrium of said heart, said atrial sensing stage configured to sense an excitation or a contraction of atrial myocardium; a ventricular sensing stage connected or being connectable to a second electrode configured to pick up electric potentials inside at least a ventricle of said heart, said ventricular sensing stage configured to sense an excitation or a contraction of ventricular myocardium; a memory configured to store AV-delay values; a control unit that is connected to said memory, at least one sensing stage and to said stimulation pulse generator, said control unit configured to trigger said stimulation pulse generator to generate ventricular stimulation pulses that are timed based on said AV-delay values stored in said memory and to acquire atrioventricular interval samples that represent time interval AsVs or ApVs between an atrial sense event As or an atrial stimulation pulse Ap, respectively, and a subsequent ventricular sense event; an atrioventricular interval timing analyzing unit that is part of said control unit or that is connected to said control unit wherein said atrioventricular interval timing analyzing unit is configured to receive atrioventricular interval samples from said control unit wherein said atrioventricular interval timing analyzing unit is further configured to generate at least one histogram based on said atrioventricular interval samples received from said control unit and analyze said at least one histogram to determine a m th q-quantile atrioventricular interval based on counts in said at least one histogram with 0<m<q; wherein said atrioventricular interval timing analyzing unit is further configured to accumulate and analyze atrioventricular intervals recorded over at least 24-hr, while a long AV delay of 250 ms to 300 ms for ventricular stimulation is utilized; check for evidence of native or natural atrioventricular conduction leading to intrinsic ventricular events Vs wherein if no evidence of native AV conduction are found, then store AV delay values into an AV delay memory and without enablement of AV hysteresis and if sufficient evidence of native AV conduction are found, then determine a longer edge of a distribution of recorded atrioventricular intervals, and determine a AV delay that corresponds to a desired high percentile of recorded atrioventricular intervals greater than a median value; calculate atrial latency time set a hysteresis AV delay to said AV delay that corresponds to said desired high percentile of recorded atrioventricular intervals.