Relationship between abnormal microvolt T-wave alternans and poor glycemic control in type 2 diabetic patients.
BACKGROUND
Abnormal microvolt T-wave alternans (TWA) predicts the risk of ventricular arrhythmias and sudden cardiac death. Although type 2 diabetes is associated with an increased risk of these events, there is a dearth of available data on microvolt TWA measurements in type 2 diabetic populations.


METHODS
We studied 59 consecutive type 2 diabetic outpatients without manifest cardiovascular disease (CVD) and 35 non-diabetic controls who were matched for age, sex, and blood pressure values. Microvolt TWA analysis was performed non-invasively using the CH-2000 system during a sub-maximal exercise with the patient sitting on a bicycle ergometer.


RESULTS
The frequency of abnormal TWA was significantly higher in diabetic patients than in controls (25.4 vs 5.7%; P < 0.01). Among diabetic patients, those with abnormal TWA (n = 15) had remarkably higher hemoglobin A1c (HbA1c) (8.1 +/- 0.9 vs 7.1 +/- 0.8%, P < 0.001) and slightly smaller time-domain heart rate variability parameters (i.e., RMSSD, root mean square of difference of successive R-R intervals) than those with normal TWA (n = 44). Gender, age, body mass index, lipids, blood pressure values, cigarette smoking, diabetes duration, microvascular complication status, QTc interval, and current use of medications did not significantly differ between the groups. In multivariate regression logistic analysis, HbA1c (OR 13.6, 95% CI 2.0-89.1; P = 0.0076) predicted abnormal TWA independent of RMSSD values and other potential confounders.


CONCLUSIONS
Our findings suggest that abnormal TWA is a very common condition (approximately 25%) among people with type 2 diabetes without manifest CVD and is closely correlated to glycemic control.
Molon
Giulio
G
Division of Cardiology, Sacro Cuore Hospital, Negrar (VR), Verona, Italy.
Costa
Alessandro
A
Bertolini
Lorenzo
L
Zenari
Luciano
L
Arcaro
Guido
G
Barbieri
Enrico
E
Targher
Giovanni
G
D000368:Aged; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis
D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human