Association Between Photoplethysmography Pulse Upslope and Cardiovascular Events in over 170,000 UK Biobank Participants

Abstract

Photoplethysmography (PPG) is used in many wearable devices and it is becoming the most commonly measured cardiovascular signal, but its association with cardiovascular events is undetermined. This study uses data from the UK Biobank to assess the association between PPG morphological features and risk of cardiovascular (CV) events. N=175,284 individuals without CV disease were included (44.6% male, $56.4\pm 8.1$ years old). A single finger PPG waveform of 101 data points, evenly sampled over the cycle length was available. The PPG waveforms were normalized between 0 and 1 and the maximum of the first derivative during the pulse's upslope was measured $(x_{MAX}^{\prime})$. Cox regressions were used to assess the association between $x_{MAX}^{\prime}$ and mortality and cardiovascular events. After a median follow-up period of 11.2 years, incidence of all-cause mortality (ACM), myocardial infarction (MI), heart failure (HF), atrial fibrillation (AF) and stroke (STR), ranged between 2.1% and 5.2%. A reduction of 1 standard deviation in $x_{MAX}^{\prime}$ was associated with increased risk of all outcomes with hazard ratio between 1.20 and 1.30. After adjusting for sex, age, and body mass index, associations remained significant for all outcomes except AF.