The present invention relates to a method and to an apparatus for treating, diagnosing and/or monitoring a patient having a heart, a heart rhythm comprising periodically repeating Q, R, S and T waves of an electrocardiogram and a peripheral vascular system, said electrocardiogram exhibiting a repeating QRSTQ heart rhythm having a Q-T systole duration, a T-Q diastole duration and an R-R path length, said patient having a pulse rate corresponding to said R-R path length, the apparatus comprising a plurality of electrodes attachable externally or internally to the patient for electrically stimulating the patient non-invasively or invasively, in synchronization with the heart rhythm, by trains of pulses applied to the patient, determining, for cycles of the heart rhythm, a time corresponding to the end of an associated T-wave and applying trains of electrical stimulation pulses within a range of −；15% to −；1% corresponding to said R-R path length before the end of the T-wave and having a train duration selected in the range of 5 to 15% of said R-R path length, so that the train of stimulation pulses ends at at most +5% RR from the end of the T-wave.
