Trend extraction in functional data of R and T waves amplitudes of exercise electrocardiogram

TL;DR

This study analyzes R and T wave amplitudes in exercise ECGs using functional data techniques, revealing opposite stress responses and their relation to ventricular volumes.

Contribution

It introduces a functional data analysis approach to identify and characterize stress-induced trends in ECG wave amplitudes.

Findings

R and T wave amplitudes respond oppositely to stress

Identified a bump in R waves and a dip in T waves during early recovery

Supported a link between wave amplitudes and ventricular volumes

Abstract

The R and T waves amplitudes of the electrocardiogram recorded during the exercise test undergo strong modifications in response to stress. We analyze the time series of these amplitudes in a group of normal subjects in the framework of functional data, performing reduction of dimensionality, smoothing and principal component analysis. These methods show that the R and T amplitudes have opposite responses to stress, consisting respectively in a bump and a dip at the early recovery stage. We test these features computing a confidence band for the trend of the population mean and analyzing the zero crossing of its derivative. Our findings support the existence of a relationship between R and T wave amplitudes and respectively diastolic and systolic ventricular volumes.