Association between physical activity and change in renal function in patients after acute myocardial infarction
RESEARCH ARTICLE
Association between physical activity and
change in renal function in patients after
acute myocardial infarction
Toshimi Sato ID1,2, Masahiro Kohzuki1*, Masahiro Ono3, Mitsuru Muto3, Taku Osugi3,
Keiichi Kawamura3, Wakako Naganuma3, Masayuki Sato4, Namiko Shishito3
1 Department of Internal Medicine and Rehabilitation Science, Tohoku University Graduate School of
Medicine, Sendai, Japan, 2 Department of Rehabilitation, Southern Tohoku General Hospital, Koriyama,
Japan, 3 Department of Cardiology, Southern Tohoku General Hospital, Koriyama, Japan, 4 Department of
Cardiology, Ohara General Hospital, Fukushima, Japan
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Abstract
Background
OPEN ACCESS
Citation: Sato T, Kohzuki M, Ono M, Muto M,
Osugi T, Kawamura K, et al. (2019) Association
between physical activity and change in renal
function in patients after acute myocardial
infarction. PLoS ONE 14(2): e0212100. https://doi.
org/10.1371/journal.pone.0212100
Editor: Tatsuo Shimosawa, International University
of Health and Welfare, School of Medicine, JAPAN
Received: October 20, 2018
Accepted: January 28, 2019
Published: February 19, 2019
Copyright: © 2019 Sato et al. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which
permits unrestricted use, distribution, and
reproduction in any medium, provided the original
author and source are credited.
Data Availability Statement: All relevant data are
within the manuscript and its Supporting
Information files.
Funding: The authors received no specific funding
for this work.
Competing interests: The authors have declared
that no competing interests exist.
Combined renal dysfunction worsens the subsequent prognosis in patients after acute myocardial infarction (AMI). Therefore, establishing a therapeutic modality to maintain or
improve renal function in AMI patients is necessary. This study aimed to elucidate the association between physical activity level and change in renal function in such patients.
Design
Prospective and observational study.
Methods
We enrolled 41 patients (35 men; average age, 67.5 ± 12.6 years) after AMI onset. Blood
biochemistry, urinalysis, and physical function tests were conducted at discharge and 3
months after discharge. Renal function was evaluated based on cystatin C based-estimated
glomerular filtration rate (eGFRcys). The number of steps was recorded for 3 months postdischarge. Generalized estimating equations (GEE) was used to test the association
between physical activity level and within-patient changes in eGFRcys.
Results
Patients were stratified into low (n = 21; number of steps, 2335 ± 1219 steps/day) and high
groups (n = 20; number of steps, 7102 ± 2365 steps/day). eGFRcys significantly increased
from baseline to after 3 months in the high group (76.5 ± 13.8 to 83.2 ± 16.0 mL/min/1.73
m2, q = 0.004), whereas no significant change was observed in the low group (65.1 ± 15.9 to
62.2 ± 20.2 mL/min/1.73 m2, q = 0.125). Result of GEE adjusted for potential confounding
variables showed a significant positive association between physical activity level and
within-patient changes in eGFRcys (p = 0.003). Changes in eGFRcys was -2.9 mL/min/1.73
m2 among low group versus +6.7 mL/min/1.73 m2 among high group.
PLOS ONE | https://doi.org/10.1371/journal.pone.0212100 February 19, 2019
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Physical activity and renal function after AMI
Conclusions
Physical activity level was positively associated with changes in renal function, demonstrating that high physical activity may suppress renal function decline in patients after AMI.
Introduction
Ischemic cardiac events, such as acute myocardial infarction (AMI), cause a decline in renal
function [1]. Furthermore, in patients after AMI, combined renal dysfunction increases subsequent total mortality and cardiovascular death [2]. The progression of chronic kidney disease
(CKD) worsens the success rate of percutaneous coronary intervention (PCI) and prognosis
[3,4]. Accordingly, establishing a therapeutic modality to maintain or improve renal function
in patients after AMI is important. In recent years, renal function has been recognized as a
new target for exercise-based cardiac rehabilitation [5], and we previously demonstrated the
renal-protective effects of chronic exercise in an experimental animal model [6]. Additionally,
cardiac rehabilitation focusing mainly on supervised exercise therapy for AMI patients [7], or
a group of patients with heart disease including those with AMI [8,9], was reported to be associated with maintaining and improving renal function. These reports suggest the possibility of
kidney protection through exercise in AMI patients. However, in Japan, the rate of cardiac
rehabilitation implementation for outpatients after AMI is very low [10,11]. In many cases,
patients select remote exercise management, such as maintaining physical activity level in
daily life and walking based on education by medical staff, such as doctors or physiotherapists.
Therefore, elucidating whether physical activity level in the daily life of AMI patients has an
effect on the changes in renal function is necessary, but there are no previous reports. Furthermore, most previous studies that examined the effect of exercise on renal function in AMI
patients estimated renal function with serum creatinine, which depends on skeletal muscle
mass [12]. Physical activity, including exercise, can change serum creatinine levels via changes
in skeletal muscle mass. Therefore, the use of cystatin C, which is independent of skeletal muscle mass, is recommended when examining the effects of physical activity on renal function
[13]. Accordingly, the aim of this study was to elucidate the association between physical activity level and changes in renal function in patients after AMI using cystatin C.
Materials and methods
Study design and patients
This study was a prospective observational study, as shown in Fig 1. In this study, the followup period was decided to be 3 months with reference to a previous study [12] that examined
the effect of exercise on renal function in AMI patients. Forty-one patients who were admitted
to Southern Tohoku General Hospital from May 2017 to June 2018 due to AMI onset and who
underwent PCI and cardiac rehabilitation during hospitalization were enrolled in the study.
Exclusion criteria were as follows: refusal or inability to provide informed consent; follow-up
not possible for 3 months after discharge; dependence on others for activities of daily living;
receiving maintenance hemodialysis therapy; complicated by other acute diseases; underwent
invasive treatments such as surgical operation during hospitalization or follow-up; and a diagnosis of dementia.
This study was conducted in accordance with the Helsinki Declaration. It was approved by
the Ethics Committee of Tohoku University Graduate School of Medicine (Approval No.
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