Novel spectral indexes of heart rate variability as predictors of sudden and non-sudden cardiac death after an acute myocardial infarction.
BACKGROUND
Various indexes of 24-hour heart rate variability (HRV) have been able to predict all-cause mortality after an acute myocardial infarction (AMI), but their value in predicting specific modes of cardiac death has been limited.


OBJECTIVE
The aim of this study was to assess the role of two novel spectral indexes of HRV as predictors of either sudden (SCD) or non-sudden cardiac death after an AMI. Method. We used two novel methods of spectral analysis of HRV: 1) the high-frequency (HF) spectral component, V(index), calculated as an average HF power from the most linear portion of HF power versus the R-R interval regression curve, and 2) the prevalent low-frequency oscillation of heart rate (PLF). V(index), conventional HRV measures, and PLF were analyzed from 24-hour Holter recordings of 590 patients with a recent AMI.


RESULTS
During the mean follow-up of 39+/-14 months, SCD occurred in 3% (n = 17) and non-sudden cardiac death in 5% (n = 28) of the patients. In univariate analysis, V(index) was the most potent predictor of SCD (RR: 6.0, 95% CI: 1.7-20.7, P<0.01), also remaining the most powerful predictor of SCD after adjustment for clinical variables and ejection fraction (RR: 4.2, 95% CI: 1.2-15.2, P<0.05). PLF was a potent predictor of non-sudden cardiac death (RR: 13.9, 95% CI: 5.9-32.5, P<0.001), but it did not predict SCD.


CONCLUSIONS
Novel spectral HRV analysis methods, V(index) and PLF, provide significant information of the risk of the specific mode of death after an AMI.
Kiviniemi
Antti M
AM
Merikoski Rehabilitation and Research Centre, Oulu, Finland.
Tulppo
Mikko P
MP
Wichterle
Dan
D
Hautala
Arto J
AJ
Tiinanen
Suvi
S
Seppänen
Tapio
T
Mäkikallio
Timo H
TH
Huikuri
Heikki V
HV
D002940:Circadian Rhythm / Q000502:physiology*; D016757:Death, Sudden, Cardiac / Q000453:epidemiology* / Q000209:etiology; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000401:mortality* / Q000503:physiopathology; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate; D013997:Time Factors; D014630:Vagus Nerve / Q000503:physiopathology; D016277:Ventricular Function, Left / Q000502:physiology