ABSTRACT
Among clinical conditions, heart rate (HR) variability, a measure of cardiac autonomic regulation, has been most widely studied in patients who have experienced acute myocardial infarction (AMI). The prognostic significance of several HR variability variables, including classic time- and frequency-domain parameters as well as some nonlinear and newer parameters, has been assessed in post-AMI patients. Schneider and Costiloe studied the prognostic significance of HR variability in ischemic heart disease and proposed that decreased HR variability in patients with AMI is associated with a worse prognosis. Some studies have suggested that some of the nonlinear parameters of HR variability may be slightly better predictors of mortality in post-AMI patients than the conventional measurements. HR variability values are dependent on HR, with values of nonlinear HR variability measurements being somewhat less dependent than those of the conventional measurements. The current evidence is strong about the predictive power of many HR variability indexes, when measured either early or late after AMI.
