Modulation of the electrocardiogram and arhythmias in diabetics.

Diabetes is a cause of serious myocardial disease related to an increased i ncidence of coronary artery disease, probably aggravated by cardiac autonom ic neuropathy (CAN). In its incipient form, CAN hardly changes the sinus rh ythm with an increase in nocturnal heart rate but without an appreciable ef fect on the indices of variability. In more advanced forms "CAN" there are not only changes in the heart rate Variability but also in ventricular repo larisation. It is classical to underline the value of the corrected QT inte rval but this index has little real value. The QT dispersion, comparing the duration of ventricular repolarisation on the surface leads, is no better a marker from the theoretical point of view The dynamics of Ventricular repolarisation on the other hand seem to be muc h more indicative of ventricular myocardial disease. They are studied by ev aluating the CT-heart rate relationship and its increase distinguishes clea rly CAN diabetics from CAN + diabetics. In addition, in the latter sujects, diurnal physiological increase in the heart rate dependency of the QT inte rval (QT/RR slope) disappears or even inverses. It is probably this phenomenon which is responsible for the traditionally i ncreased risk of ventricular arrhythmias and particularly sudden death in d iabetics with autonomic neuropathy.