Average T-wave alternans activity in ambulatory ECG records predicts sudden cardiac death in patients with chronic heart failure.
BACKGROUND
T-wave alternans (TWA) is a well-documented noninvasive electrocardiographic (ECG) method useful for identifying patients at risk for sudden cardiac death (SCD).


OBJECTIVE
The purpose of this study was to evaluate whether the long-term average TWA activity on Holter monitoring provides prognostic information in patients with chronic heart failure.


METHODS
Twenty-four-hour Holter ECGs from 650 ambulatory patients with mild-to-moderate chronic heart failure were analyzed in the study. Average TWA activity was measured by using a fully automated multilead technique, and 2 indices were proposed to quantify TWA: an index quantifying the average TWA activity in the whole recording (IAA), which was used to define a positive/negative TWA test, and an index quantifying the average TWA activity at heart rates between 80 and 90 beats/min (IAA(90)).


RESULTS
Patients were divided into TWA positive (TWA+) and TWA negative (TWA-) groups by setting a cut point of 3.7 μV for IAA, corresponding to the 75th percentile of the distribution of IAA in the population. After a median follow-up of 48 months, the survival rate was significantly higher in the TWA- group for cardiac death and SCD (p = .017 and p = .001, respectively). Multivariate Cox proportional hazards analysis revealed that both TWA+ and IAA(90) were associated with SCD with hazard rates of 2.29 (p = .004) and 1.07 per μV (p = .046), respectively.


CONCLUSIONS
The average TWA activity measured automatically from Holter ECGs predicted SCD in patients with mild-to-moderate chronic heart failure.
CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Zaragoza, Aragon, Spain. violeta@unizar.es
Violeta
V
Monasterio
Pablo
P
Laguna
Iwona
I
Cygankiewicz
Rafael
R
Vázquez
Antoni
A
Bayés-Genís
Antoni Bayés
AB
de Luna
Juan Pablo
JP
Martínez
D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000209:etiology / Q000401:mortality; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control*; D015716:Electrocardiography, Ambulatory / Q000379:methods / Q000592:standards; D005260:Female; D006333:Heart Failure / Q000150:complications / Q000175:diagnosis / Q000401:mortality; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology; D015996:Survival Rate