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[Electrocardiographic changes and rhythm problems in the diabetic]
P Coumel1, N Johnson, F Extramiana
1Hôpital Lariboisière, 2, rue Ambroise-Paré, 75010 Paris.
Insights
Diabetes can lead to cardiac autonomic neuropathy (CAN), affecting heart rate and repolarization dynamics. Advanced CAN in diabetics increases risks for arrhythmias and sudden cardiac death.
Area of Science:
- Cardiology
- Diabetology
- Autonomic Nervous System Research
Context:
- Diabetes mellitus is a significant risk factor for cardiovascular complications.
- Cardiac autonomic neuropathy (CAN) is a common complication, exacerbating myocardial disease.
- Early stages of CAN may present subtle changes, while advanced forms impact heart rate variability and ventricular repolarization.
Purpose:
- To investigate the relationship between cardiac autonomic neuropathy (CAN) and myocardial disease in diabetic patients.
- To evaluate the diagnostic value of ventricular repolarization dynamics, specifically the QT-heart rate relationship, in assessing CAN progression.
- To explore the link between altered repolarization dynamics and the increased risk of arrhythmias and sudden death in diabetics with CAN.
Summary:
- Cardiac autonomic neuropathy (CAN) in diabetes is associated with myocardial disease and increased coronary artery disease incidence.
- While traditional markers like corrected QT interval and QT dispersion have limitations, repolarization dynamics offer better insights.
- The QT-heart rate relationship and its diurnal variations (QT/RR slope) effectively differentiate between incipient and advanced CAN (CAN+), with the latter showing a loss or inversion of the physiological QT/RR slope increase.
Impact:
- Identifies repolarization dynamics as a more sensitive indicator of myocardial disease in diabetic CAN.
- Provides a potential method to stratify risk in diabetic patients with CAN based on repolarization abnormalities.
- Highlights the pathophysiological basis for increased ventricular arrhythmias and sudden cardiac death risk in advanced diabetic CAN.
Abstract:
Diabetes is a cause of serious myocardial disease related to an increased incidence of coronary artery disease, probably aggravated by cardiac autonomic neuropathy (CAN). In its incipient form, CAN hardly changes the sinus rhythm with an increase in nocturnal heart rate but without an appreciable effect on the indices of variability. In more advanced forms, "CAN+", there are not only changes in the heart rate variability but also in ventricular repolarisation. It is classical to underline the value of the corrected QT interval 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 much more indicative of ventricular myocardial disease. They are studied by evaluating the QT-heart rate relationship and its increase distinguishes clearly CAN diabetics from CAN+ diabetics. In addition, in the latter subjects, diurnal physiological increase in the heart rate dependency of the QT interval (QT/RR slope) disappears or even inverse. It is probably this phenomenon which is responsible for the traditionally increased risk of ventricular arrhythmias and particularly sudden death in diabetics with autonomic neuropathy.