Baroreflex
Sensitivity Determined by Spectral Method and
Heart Rate Variability, and Two-Years Mortality
in Patients After Myocardial Infarction
N. HONZÍKOVÁ1, B.
SEMRÁD2, B. FIŠER1,
R. LÁBROVÁ2
1Department
of Physiology, Faculty of Medicine and 2First
Department of Medicine, Faculty of Medicine, Masaryk University, Brno, Czech Republic
Received
February 14, 2000
Accepted August 7, 2000
Summary
Sympathetic
overactivity and low parasympathetic activity is
an autonomic dysfunction (AD) which enhances
cardiac mortality. In the present study, the
impact of AD on the mortality in patients after
myocardial infarction was evaluated. We examined
162 patients 7-21 days after myocardial
infarction, 20 patients of whom died in the
course of two years. Baroreflex sensitivity (BRS)
was estimated by spectral analysis of spontaneous
fluctuations of systolic blood pressure and
cardiac intervals (Finapres, 5 min recording,
controlled breathing 20/min). The heart rate
variability was determined as SDNN index (mean of
standard deviations of RR intervals for all 5-min
segments of 24-hour ECG recordings). BRS < 3
ms/mm Hg and/or SDNN index < 30 ms were taken
as markers of AD. The risk stratification was
performed according to the number of the
following standard risk factors of increased risk
of cardiac mortality (SRF): ejection fraction
< 40 %, positive late potentials and the
presence of ventricular extrasystoles > 10/h.
No difference in mortality between patients with
AD (4 %) and without AD (4.5 %) was found in 92
patients without SRF, the mortality in 6 patients
with three SRF was 66.6 %. Five of these patients
had AD. Out of 64 patients with one or two SRF,
32 had AD. The mortality of patients without AD
was 6.25 % and 31.2 % of those with AD
(p<0.025). It is concluded that AD enhanced
two-years mortality five fold in our patients
with moderate risks.
Key words
Baroreflex
sensitivity · Spectral analysis · Myocardial
infarction · Cardiac death · Risk
stratification
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Prof.
Dr. Nataša Honzíková, Department of
Physiology, Faculty of Medicine, Komenského nám.
2, 662 43 Brno, Czech Republic. Fax: +420-5-42126
561, E-mail: nhonziko@med.muni.cz
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