Heart rate variability after myocardial infarction: what we know and what we still need to find out.

Heart rate variability (HRV) is represented by the variation of the time intervals between consecutive heartbeats or the instantaneous heart rates, and can be assessed with linear and non-linear parameters. It is a sensitive indicator of an overall system complexity and adaptability and can be used to diagnose the autonomic dysfunction and quantify the associated risk in a variety of cardiac and non-cardiac disorders. The aim of this review is to summarize the current literature on the value of HRV in predicting the risk of long-term all cause, cardiac, and arrhythmic mortality in survivors of myocardial infarction (MI). We also emphasize the lack of evidence on the role of therapeutic interventions such as medications, bio-behavioral treatments, cardiac rehabilitation, and exercise, in modifying the HRV in post-MI patients.