Quantitative T-wave alternans analysis for sudden cardiac death risk assessment and guiding therapy: answered and unanswered questions: For: Proceedings of ICE2015 Comandatuba, Brazil, Sudden Death Symposium.

This review addresses current questions regarding use of T-wave alternans to stratify risk for sudden cardiac death. Both of the currently available commercial methodologies, namely, the frequency-domain spectral method and the time-domain modified moving average (MMA) method, are supported by guideline statements, cleared by the US FDA, and covered by the US Center for Medicare and Medicaid services. Similar numbers of patients have been enrolled in predictive studies; odds ratios generated by the two methods are similar including in a head-to-head study. However, in two prospective studies, prediction by TWA with the spectral method was negative, likely due to withdrawal of beta-blockade before the test with later resumption, while all studies with MMA have achieved prediction when the commercial software was used appropriately. Questions currently undergoing investigation include TWA's potential to guide ICD implantation, to track changes in risk during cardiac disease progression, and to evaluate the adequacy of medical therapy.