Prevalence of Q-T interval dispersion in type 1 diabetes and its relation with cardiac ischemia : the EURODIAB IDDM Complications Study Group.
OBJECTIVE
The interlead variation in duration of the Q-T interval on the surface electrocardiogram (Q-T interval dispersion [QTd]) has been shown to predict mortality in type 2 diabetic patients. We evaluated the prevalence of QTd prolongation in the EURODIAB population and its relation to corrected Q-T interval (QTc), sex, age, duration of diabetes, blood glucose control, and complications. RESEARCH DESIGN AND METHODS; A total of 3,042 type 1 diabetic patients were studied. QTc was calculated according to the Bazett's formula; QTc > 0.44 s was considered abnormally prolonged. QTd was calculated using the difference between the maximum and the minimum QTc in any thoracic lead. QTd >0.080 s was considered abnormally prolonged.


RESULTS
The prevalence of an increased QTd was 7%. A significant relation was observed between QTd prolongation and diastolic blood pressure (P < 0.05). A higher prevalence of QTd prolongation was observed in patients with ischemic heart disease (P = 0.004), whereas no relationship was observed with retinopathy, albumin excretion rate, or measures of somatic and autonomic neuropathy. QTc and QTd were significantly related (P = 0.001); however, a proportion of patients with normal QTd showed a prolonged QTc (>0.44 s).


CONCLUSIONS
In patients with type 1 diabetes, QTd is associated with ischemic heart disease and diastolic blood pressure but not neuropathy. Although QTd is statistically related to duration of QTc, increased QTd and increased QTc identify different patients, and their predictive value deserves prospective evaluation.
Veglio
Massimo
M
Evangelico Valdese Hospital, Turin, Italy. veglio@onw.net
Giunti
Sara
S
Stevens
Linda K
LK
Fuller
John H
JH
Perin
Paolo Cavallo
PC
D000328:Adult; D000419:Albuminuria; D001824:Body Constitution; D015992:Body Mass Index; D003922:Diabetes Mellitus, Type 1 / Q000139:chemically induced / Q000503:physiopathology*; D003925:Diabetic Angiopathies / Q000453:epidemiology; D003928:Diabetic Nephropathies / Q000453:epidemiology; D003929:Diabetic Neuropathies / Q000453:epidemiology; D003930:Diabetic Retinopathy / Q000453:epidemiology; D006801:Humans; D008133:Long QT Syndrome / Q000453:epidemiology*; D017202:Myocardial Ischemia / Q000453:epidemiology*; D015995:Prevalence