Circadian Modulation on T-wave Alternans Activity in Chronic Heart Failure Patients

Abstract

Average TWA activity has been shown to be an independent predictor of sudden cardiac death (SCD) in chronic hean failure (CHF) patients% flowerer the influence o f cireadian rhythms on TWA remains understudied. In this work, we assessed circadian TWA changes in a CHF population and evaluated whether the prognostic value of TWA indices Ls sensitive to the circadian pattern. Hotter ECG recordings from 626 consecutive CHF patients (52 SCD) were analyzed. The index of average altemans (IAA), quantiffing the average TWA level, was measured in 4 consecutive 6-hour intervals using a multi lead fully-cuttomated method. Survival analysis vvas performed considering SCD as an independent endpoint. IAA changed along the day,. with statistically significtmt lower values during the night than during daytime. This patterrt is similar to the one observed in the mean heart rate (HR). However, a low correlation (r= 18) was found between MA and HR in windows of 128 heats. After dichototnizatthn f patients based on the third quartile of IAA indices, IAA indices computed between hours 06-12 (IAA,) and 18-24 (1AA,) successfully predicted SCD (Hazard Ratio, HaR.-2.34( 1.33-4.13) per IN, and HaR:1.87(1.04-3.36) per ktV, respectively). In conclusion, circadian variation should be considered for SCD risk prediction.