Influence of diabetes and/or myocardial infarction on prevalence of abnormal T-wave alternans.
BACKGROUND
Subjects with microvolt-level T-wave alternans (TWA) in association with structural heart disease have an increased risk for sudden cardiac death. The presence of diabetes (DM) is associated with an increased risk of sudden death but there is limited data on the impact of DM and previous myocardial infarction (MI) on TWA prevalence.


METHODS
We performed a case-control cross-sectional study in 140 patients referred for routine exercise testing within a large multispecialty clinic. All patients with a history of DM and MI status within the past year were eligible: group 1 (no DM or MI), group 2 (DM only), group 3 (MI only), group 4 (DM and MI). Patients performed a symptom-limited Bruce protocol exercise test with assessment of TWA by the spectral method using commercially available equipment. We used published criteria for the blinded interpretation of TWA; all tests not unequivocally negative were considered abnormal.


RESULTS
Age and gender were similar in all groups. The prevalence of abnormal TWA in groups 1-4 was 24%, 20%, 48%, and 62%, respectively (between group P = 0.002). Logistic regression analysis in all patients showed that abnormal TWA was related to prior MI [OR (95% CI): 4.0 (1.8-8.9), P < 0.001] but not to prevalent DM [0.9 (0.4-1.8), P = 0.72]. In patients with DM, the prevalence of abnormal TWA was related to reduced ejection fraction (P = 0.034) but not to BMI, DM duration, glycemic control, insulin use, or the presence of microvascular complications.


CONCLUSIONS
The presence of DM alone does not increase risk of abnormal TWA. Prospective studies are required to establish the prognostic value of TWA in patients with DM.
Department of Cardiovascular Medicine, Lahey Clinic Medical Center, Burlington, MA 01805, USA. david.t.martin@lahey.org
David T
DT
Martin
Azadeh
A
Shoraki
Richard W
RW
Nesto
Martin K
MK
Rutter
D000704:Analysis of Variance; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D016022:Case-Control Studies; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D016757:Death, Sudden, Cardiac / Q000453:epidemiology; D003920:Diabetes Mellitus / Q000453:epidemiology / Q000503:physiopathology*; D005080:Exercise Test / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology / Q000503:physiopathology*; D015995:Prevalence; D012307:Risk Factors; D018487:Ventricular Dysfunction, Left / Q000453:epidemiology / Q000503:physiopathology