The coin toss: implications for risk stratification for sudden cardiac death.

A number of risk stratification techniques have been used to identify groups of patients at risk for sudden cardiac death. These tests applied in populations do not necessarily provide adequate differentiation of high versus low risk for an individual patient. For the individual patient, the physician must act on the observed results; hence, the positive and negative predictive values of the test become a major driver of its utility for the individual patient. The positive and negative predictive values of multiple tests from 2 trials are compared with the positive and negative predictive values of a "coin toss" to illustrate the limited ability of individual tests to adequately risk stratify. Alternative approaches to achieve better risk stratification are highlighted.