Improved robust T-wave alternans detectors
New statistical and spectral detectors, the modified matched pairs t test, the extended spectral method and the modified spectral method, were proposed for T-wave alternans (TWA) detection gaining robustness according to trend and single-frequency interferences. They were compared to classic detectors such as matched pairs t test, unpaired t test, spectral method, generalized likelihood ratio test and estimated TWA amplitude within a simulation framework and applied to real data. The optimal detection threshold was selected by using a full Monte-Carlo simulation where signals, with and without alternans episodes, were corrupted by Gaussian noise with different power and single-frequency interferences with different tones. All the combinations of noise and frequency were selected and repeated 500 times in order to compute probability of detection (\(P_{\mathrm{d}}\)) and the false alarm probability (\(P_{\mathrm{fa}}\)), providing ROC curves. The study group consisted of 50 patients with implantable cardioverter-defibrillator (age: \(55.3 \pm 16.4\); LVEF: \(42.8 \pm 15.5\)), who were paced (ventricular pacing) at 100 bpm. Two-minute recordings were analyzed. The XYZ orthogonal lead system was used. The best performance was reached by using the modified matched pairs t test (in comparison with the spectral method and other reference methods).
t-wave alternans detector electrocardiography ventricular arrhythmia