Figure 1.

Prediction of events depends on definition of “events”. Comparison of prospective clinical trials evaluating T-wave alternans (TWA) measured using the spectral analytic method in primary prevention populations in which (1) few patients had implantable cardioverter defibrillators (ICD) and as a result none or a small fraction (≤ 15%) of the reported endpoint ventricular tachyarrhythmic events (VTEs) were ICD-detected (Low ICD Group) or (2) many of the patients had implanted ICDs and the majority of the reported endpoint VTEs were ICD-detected (High ICD Group). In the Low ICD Group comprising 3,682 patients, the hazard ratio associated with a TWA + vs TWA - was 13.6 (8.5 - 30.4) and the annual event rate (AER) among the TWA - patients was 0.3% (0.1% - 0.5%). In contrast, in the High ICD Group comprising 2,234 patients, the hazard ratio was only 1.6 (1.2 - 2.1) and the AER among the TWA - patients was elevated to 5.4% (4.1% - 6.7%). Adapted from Hohnloser et al.²⁰