Relationship Between Abnormal Microvolt T-Wave

Alternans and Poor Glycemic Control in Type 2

Diabetic Patients

GIULIO MOLON, M.D.,* ALESSANDRO COSTA, M.D.,* LORENZO BERTOLINI, M.D.,†

LUCIANO ZENARI, M.D.,† GUIDO ARCARO, M.D.,† ENRICO BARBIERI, M.D., F.A.C.C.,*

and GIOVANNI TARGHER, M.D.†‡

From the *Division of Cardiology and †Diabetes Unit, Sacro Cuore Hospital, Negrar (VR), and ‡Section of

Endocrinology, Department of Biomedical and Surgical Sciences, University Hospital of Verona, Verona, Italy

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 (∼25%) among

people with type 2 diabetes without manifest CVD and is closely correlated to glycemic control. (PACE

2007; 30:1267–1272)

microvolt T-wave alternans, arrhythmias, glycemic control, type 2 diabetes