Is T-wave alternans T-wave amplitude dependent?

The possible dependence of T-wave alternans (TWA) on T-wave amplitude was investigated in 3 orthogonal leads (X, Y, Z) 20-min resting ECG recordings and in the derived vector magnitude (VM) from 176 healthy (H) subjects and 200 coronary-artery-disease (CAD) patients. After application of our adaptive-match-filter based method for parameterization of TWA in terms of its amplitude (TWA_A) and product-magnitude (TWA_PM, defined as the product of TWA A times TWA duration), and once a TW_A parameter was defined for T-wave amplitude quantification, the existence of intra- and intersubjects relationships of TWA_A and TWA_PM vs. TW_A was tested. Compared to the H-population, the CAD-population showed a significant (P < 0.05) increase of TWA_A (62±38 V vs. 54±25 microV) and TWA_PM (4029±2974 beat microV vs. 3107±1976 beat microV) and a significant decrease of TW_A (298±194 microV vs. 467±246 microV). These repolarization changes, however, occurred with no significant intra- or intersubjects relationships of TWA_A and TWA_PM vs. TW_A. Thus, in our CAD and H populations there was no evidence of TWA dependence on T-wave amplitude.