Increased non-Gaussianity of heart rate variability predicts cardiac mortality after an acute myocardial infarction

Junichiro Hayano, Ken Kiyono, Zbigniew R. Struzik, Yoshiharu Yamamoto, Eiichi Watanabe, Phyllis K. Stein, Lana L. Watkins, James A. Blumenthal, Robert M. Carney

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31 Scopus citations

Abstract

Non-Gaussianity index (λ) is a new index of heart rate variability (HRV) that characterizes increased probability of the large heart rate deviations from its trend. A previous study has reported that increased λ is an independent mortality predictor among patients with chronic heart failure. The present study examined predictive value of λ in patients after acute myocardial infarction (AMI). Among 670 post-AMI patients, we performed 24-h Holter monitoring to assess λ and other HRV predictors, including SD of normal-to-normal interval, very-low frequency power, scaling exponent α 1 of detrended fluctuation analysis, deceleration capacity, and heart rate turbulence (HRT). At baseline, λ was not correlated substantially with other HRV indices (|r| <0.4 with either indices) and was decreased in patients taking β-blockers (P = 0.04). During a median follow-up period of 25 months, 45 (6.7%) patients died (32 cardiac and 13 non-cardiac) and 39 recurrent non-fatal AMI occurred among survivors. While all of these HRV indices but λ were significant predictors of both cardiac and non-cardiac deaths, increased λ predicted exclusively cardiac death (RR [95% CI], 1.6 [1.3-2.0] per 1 SD increment, P< 0.0001). The predictive power of increased λ was significant even after adjustments for clinical risk factors, such as age, diabetes, left ventricular function, renal function, prior AMI, heart failure, and stroke, Killip class, and treatment ([95% CI], 1.4 [1.1-2.0] per 1 SD increment, P = 0.01). The prognostic power of increased λ for cardiac death was also independent of all other HRV indices and the combination of increased λ and abnormal HRT provided the best predictive model for cardiac death. Neither λ nor other HRV indices was an independent predictor of AMI recurrence. Among post-AMI patients, increased λ is associated exclusively with increased cardiac mortality risk and its predictive power is independent of clinical risk factors and of other HRV predictors.

Original languageEnglish
Article numberArticle 65
JournalFrontiers in Physiology
Volume2 SEP
DOIs
StatePublished - 2011

Keywords

  • Ambulatory ECG
  • ENRICHD study
  • Heart rate variability
  • Mortality
  • Myocardial infarction
  • Non-gaussianity
  • Prospective study
  • Sudden cardiac death

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