Index of T-wave variation as a predictor of sudden cardiac death in chronic heart failure patients with atrial fibrillation

Chronic heart failure (CHF) and atrial fibrillation (AF) are worldwide leading causes of morbidity and mortality in elders, a large part due to sudden cardiac deaths (SCD). The high irregularity of ventricular response in AF patients makes the use of standard SCD-risk markers inappropriate in this target population. The aim of this study was twofold: i) to propose a new index, suitable for AF patients, able to quantify ventricular repolarization changes; and ii) to evaluate its prognostic value in a CHF population with AF. Holter ECG recordings from 176 consecutive CHF patients with AF (22 SCD) were analyzed. The index of T-wave variation (I
_TV
), quantifying the average T-wave changes in pairs of consecutive beats under stable rhythm conditions, was computed using a fully-automatic method. Survival analysis was performed considering SCD as an independent endpoint. I
_TV
was higher for SCD than non-SCD victims (median (Q1;Q3): 24.9 (14.4;85.4) μV vs 17.1 (11.3;28.2) μV, p=0.06). In a survival analysis where the threshold was set on the third quartile of I
_TV
values, I
_TV
(+) outcome was successfully associated to SCD (Hazard Ratio (CI):3.22 (1.36, 7.58)per μV, p=0.008). In conclusion, we show in this work that Ijy stratifies CHF patients with AF according to their risk of SCD, with larger I
_TV
associated to lower survival probability.