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. Author manuscript; available in PMC: 2010 Aug 1.
Published in final edited form as: Heart Rhythm. 2009 Jun 23;6(8 Suppl):S56–S61. doi: 10.1016/j.hrthm.2009.05.025

Figure 2.

Figure 2

T-wave alternans (TWA) is a marker of the sudden cardiac death phenotype. Upper Panel: Mortality rates from the main SCD Heart Failure Trial (SCD-HeFT). This plot shows that the beneficial effect of ICD therapy in SCD-HeFT begins to emerge between 18 and 24 months (dashed line). Lower Panel: Event rates from the TWA substudy of SCD-HeFT. The time base is scaled to match the survival curves from the main SCD-HeFT trial (upper), permitting comparison of the time course of an apparent prognostic TWA signal (i.e. separation of TWA + and TWA - curves) and the emergence of a detectable SCD phenotype in the same population. These data show that the TWA begins to develop at the same time as the SCD phenotype becomes detectable.28