Despite a well-established prognostic value in cardiac patients, HRV (heart rate variability) indexes have been used little in the clinical setting. Poor reliability of the measurements might be a possible explanation for this. In the present study, we assessed the reliability of short-term HRV indexes in post-MI (myocardial infarction) patients. We studied 61 MI patients [50 males; age, 59±8 years; and LVEF (left ventricular ejection fraction), 46±6%; values are means±S.D.], who underwent a 5+5 min ECG recording during spontaneous and paced breathing on two consecutive days. Standard time-domain [SDNN (S.D. of RR interval values) and RMSSD (root-mean-square of successive RR interval differences)] and frequency-domain [LF (low-frequency) and HF (high-frequency) power, and LF/HF] indexes of HRV were computed. Absolute and relative reliability were assessed by the 95% limits of random variation and by the ICC (intra-class correlation coefficient). The agreement between the two measurements in classifying patients at low or high risk, according to different cut-points, and the sample size needed to detect a clinically relevant change, were also assessed. During spontaneous breathing, individual changes in test–retest measurements ranged from −41 to +61% (SDNN; best case) and from −76 to +316% (LF/HF; worst case). The ICC ranged from 0.72 to 0.81. Most patients (79–90%) were assigned to the same class by the two measurements. Paced breathing did not improve reliability. In conclusion, short-term HRV parameters in MI patients may have large day-to-day variations, making the detection of treatment effects in individual patients difficult; however, the ICC values and the analysis of the consistency of classification between repeated tests indicate that HRV measurements fulfil the criteria required to be used for diagnostic or classification purposes.
Reliability of heart rate variability measurements in patients with a history of myocardial infarction
Roberto Maestri, Grzegorz Raczak, Ludmila Danilowicz-Szymanowicz, Antoni Torunski, Adam Sukiennik, Jacek Kubica, Maria Teresa La Rovere, Gian Domenico Pinna; Reliability of heart rate variability measurements in patients with a history of myocardial infarction. Clin Sci (Lond) 1 February 2010; 118 (3): 195–201. doi: https://doi.org/10.1042/CS20090183
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