T Wave and QRS Complex Alternans During Stress ECG Testing According to the Presence or Absence of Diabetes Mellitus

Diabetes mellitus (DM) is a well recognised cardiovascular risk factor, associated with adverse clinical outcomes. Microvolt T wave alternans (TWA) and to some extent alternans of the QRS complex (QRSA) during stress ECG testing have the ability to detect patients at an increased risk for sudden cardiac death (SCD). The results about the influence of DM on TWA during stress testing are controversial, and studies regarding QRSA values during stress ECG testing according to the presence or absence of DM are lacking. The purpose of the present study is to evaluate the influence of DM on TWA and QRSA during stress ECG testing. Methods: Principal component analysis, combined with wave amplitude computation was used for TWA and QRSA quantification. We studied 107 patients (63 ± 10 years, 42% male). DM was present in 36% and angiographically significant coronary artery disease (AS-CAD) in 45%. Results: Patients with DM had higher QRSA compared to non-diabetics (P = 0.001); TWA did not differ significantly. Patients with positive stress ECG tests had higher TWA and QRSA compared to those with negative stress tests (P < 0.001), no matter of the presence or absence of DM. In non-diabetics TWA and QRSA values were significantly higher when percutaneous coronary intervention (PCI) was performed (P <= 0.001), while in the diabetic subgroup such a difference was attenuated to no significant. Conclusions: Diabetics had higher QRSA during stress ECG testing, while TWA values were not significantly influenced by the diabetic status. The presence of DM attenuates the observed differences of TWA and QRSA between patients with or without PCI.