# Electrocardiogram frequency characteristics study by processing and analysis of the signal in time domain and spectral domain

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## Abstract

This paper presents the results of a study in which cardiac signal of the first lead of a standard digital ECG system were processed. By filtering in the time domain, the cardiogram was clarified of noise that reduced influence of spectral harmonics by 10-15%. To present and classify frequency characteristics throughout the entire cardio signal, the QS section between the P and T peaks was smoothed. Due to the influence of sharp peaks on the results of spectral analysis, a result considerably differ from the sum of sinusoidal components is observed. The gap between the peaks is interpolated by the Lagrange polynomial since it did not show an influence on the resultant spectrum. The spectral representation revealed peaks with frequencies oddly even, 3.1 Hz and 6.2 Hz, corresponding to the P and T peaks. Based on the obtained results the frequencies corresponding to the remaining peaks of the cardiogram were also classified. The obtained results represent a spectrum of two regular harmonics what allows for further adequate diagnostics of ECG signals.

## Methods

We evaluated a total of 1078 consecutive anterior STEMI patients who underwent PPCI with deployment of new generations DES. The patients were divided according to the number of implanted stents into 2 groups; multiple-stents group having ≥2 overlapping stents (n =388) and single-stent group (n =690). We compared the rates of major adverse cardiovascular events (MACEs; composite of cardiac death, reinfarction, ischemia-driven target vessel revascularization (TVR), definite stent thrombosis (ST), and stroke) between the 2 study groups.

## Results

There was a non-significant trend toward increased in-hospital mortality in the multiple-stents group [3.4% vs 1.7%; P=0.096] related to a significant higher rate of cardiogenic shock [9.5% vs 6.1%; P=0.037] and post-procedural suboptimal TIMI flow [26.3% vs 19.4%; P=0.009] as compared to the single-stent group. Yet, there were no significant differences between the 2 groups in the incidence of 6-month MACEs: [9% vs 7.1%; P=0.259], cardiac death: [4.6% vs 3%; P=0.173], reinfarction: [3.6% vs 3.2%; P=713], TVR: [4.4% vs 4.1%; P=0.799], and definite ST: [3.6% vs 2.8%; P=0.43], respectively.

## Imprint

Vitaly O. Chereshnev, Sergey G. Proskurin. Electrocardiogram frequency characteristics study by processing and analysis of the signal in time domain and spectral domain. Cardiometry; Issue 17; November 2020; p.30-33; DOI: 10.12710/cardiometry.2020.17.3033; Available from: http://www.cardiometry.net/issues/no17-november-2020/electrocardiogram-frequency-characteristics