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