“…Repolarization alternans (RA), an electrophysiologic phenomenon consisting on everyother-beat changes of the repolarization morphology (amplitude, shape, and, sometimes, polarity) unaccompanied by gross changes in the heart-cycle length, is generally recognized as a promising electrocardiographic (ECG) predictor of sudden cardiac arrest (SCA; Bloomfield et al, 2006, Chow et al 2006, Ikeda et al, 2006, Klingenheben et al, 2000, Leino et al, 2009, Maeda et al, 2009, Narayan, 2006, Rosenbaum et al, 1994, Sakaki et al, 2009, Salerno-Uriarte et al, 2007, Stein et al, 2008, that is one of the leading causes of death in developed countries (over 300,000 lives per year in the U.S.; Montagnana at al., 2008, Zheng et al, 2001). On the ECG tracing, RA consists of an alternation of either the ST-segment (Nearing et al, 1991, Rosenbaum et al, 1994, or the T-wave, or even the U-wave (Habbab & el-Sherif, 1992).…”