The disbalance of autonomic heart regulation (AHR) develops already in the presymptomatic stage of Parkinson's disease. The early symptomatic stage is accompanied by the aggravation of heart dysfunction due to the shift of the autonomic balance towards the increase of sympathetic and decrease of parasympathic effect on the heart. Coronary disorders concomitant to Parkinson's disease increase a risk of life threatening arrhythmia and sudden death syndrome not only in the early symptomatic stage but also in the presymptomatic stage. L-DOPA effectively restores the structure of AHR and prevents the risk of life threatening arrhythmia only in the presymptomatic stage of Parkinson's disease.