T wave and QRS complex alternans during standard diagnostic stress ECG test

The aim of the present work was to study and analyse the presence of both T wave and QRS complex alternans (TWA&QRSA) during diagnostic stress ECG test using principal component analysis, and wave amplitude computation on a combined lead. We studied 57 patients at a mean age of 65 ± 12 y, 44% males. 28 of the patients had angiographically significant coronary artery disease (AS_CAD >= 50% stenosis of at least 1 epicardial coronary artery). The results showed that patients with positive stress ECG test had significantly higher TWA&QRSA values compared to patients with negative stress test (2.32 versus 1.66, p < 0.001 for TWA and 1.77 versus 1.11, p = 0.003, for QRS). Patients with AS_CAD had significantly higher QRSA, but not TWA, values (1.6 and 1.1, respectively; p = 0.017).