A new T-wave frequency based index for discrimination of abnormal repolarization

Aim of the present study was to propose an innovative TCE₁₀ index (defined as the T-wave cumulative normalized energy at 10 Hz, in %) as a useful tool to characterize the T wave in terms of its frequency content, and to test the TCE₁₀ ability to discriminate abnormal cases of repolarization. To this aim, ECG recordings (X, Y, Z leads and vector-magnitude signal, VMS) of 23 control healthy (CH) subjects and 23 antero-septal acute myocardial infarction (ASAMI) patients were analysed. Abnormal repolarization was identified when TCE₁₀ was below a threshold value, defined as the 25^th percentile of the TCE₁₀ distribution over the CH population. Results indicate that the ASAMI population was characterized by lower TCE₁₀ values than the CH population (X: 93.9±5.9% vs. 98.2±1.2%; Y: 95.2±4.5% vs. 97.8±1.4%; Z: 97.4±1.6% vs. 99.1±1.5%; VMS: 95.7±2.8% vs. 97.9±1.3%; P<;0.01). Moreover, the ASAMI patients were discriminated from the CH subjects with a lead-independent specificity of 74% and a lead-dependent sensitivity of 78%, 61%, 87% and 57% for lead X, Y, Z and VMS, respectively. In conclusion, compared to the CH subjects, the ASAMI patients show increased high-frequency spectral energy and were discriminated from the former with satisfactory values of sensibility and specificity.