Clinical Application of Heart Rate Variability after Acute Myocardial Infarction

Heikki V Huikuri,Phyllis K Stein

doi:10.3389/fphys.2012.00041

Abstract

Heart rate (HR) variability has been extensively studied in patients surviving an acute myocardial infarction (AMI). The majority of studies have shown that patients with reduced or abnormal HR variability/turbulence have an increased risk of mortality within few years after an AMI. Various measures of HR dynamics, such as time-domain, spectral, and non-linear measures of HR variability, as well as HR turbulence, have been used in risk stratification of post-AMI patients. The prognostic power of various measures, except of those reflecting rapid R–R interval oscillations, has been almost identical, albeit some non-linear HR variability measures, such as short-term fractal scaling exponent, and HR turbulence, have provided somewhat better prognostic information than the others. Abnormal HR variability predicts both sudden and non-sudden cardiac death after AMI. Because of remodeling of the arrhythmia substrate after AMI, early measurement of HR variability to identify those at high risk should likely be repeated later in order to assess the risk of fatal arrhythmia events. Future randomized trials using HR variability/turbulence as one of the pre-defined inclusion criteria will show whether routine measurement of HR variability/turbulence will become a routine clinical tool for risk stratification of post-AMI patients.

Highlights

FOR ABNORMAL HR VARIABILITY Heart rate variability is a term that encompasses a large number of measures of different types that have been described in details in other articles of this Special Topic of the journal
Heart rate (HR) variability has been extensively studied in patients surviving an acute myocardial infarction (AMI)
The majority of studies have shown that patients with reduced or abnormal HR variability/turbulence have an increased risk of mortality within few years after an AMI

Summary

BACKGROUND

FOR ABNORMAL HR VARIABILITY Heart rate variability is a term that encompasses a large number of measures of different types that have been described in details in other articles of this Special Topic of the journal. Timedomain measures reflect “how much” HRV there is. If such measures are extremely low, it can be assumed that there is true autonomic dysfunction, but higher values for these various measures could reflect more healthy autonomic function or an unhealthy, highly irregular HR pattern (erratic rhythm). Low values are associated with a lack of autonomic modulation of HR, but higher values, without examination of their underlying organization using power spectral plots or other graphical methods, cannot be assumed to reflect better HR variability. Nonlinear measures like the short-term fractal scaling exponent and the power–law slope, appear to better differentiate between healthy and unhealthy organization of the heart’s rhythm and have proved to be more sensitive for risk stratification that some of the standard measures (Bigger et al, 1996; Huikuri et al, 2000).

ECG documental VT or VF

VLF power was the strongest predictor