Association of Estimated Central Blood Pressure Measured Non-invasively with Pulse Wave Velocity in Patients with Coronary Artery Disease

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Letter to the Editor
Association of estimated central blood pressure measured non-invasively
with pulse wave velocity in patients with coronary artery disease
Daisuke Sueta
a
, Eiichiro Yamamoto
a,
⁎, Tomoko Tanaka
b
, Yoshihiro Hirata
a
, Kenji Sakamoto
a
, Kenichi Tsujita
a
,
Sunao Kojima
a
, Koichi Nishiyama
b
,KoichiKaikita
a
, Seiji Hokimoto
a
, Hideaki Jinnouchi
b
, Hisao Ogawa
a
a
Department of Cardiovascular Medicine, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan
b
Division of Preventive Cardiology, Department of Cardiovascular Medicine, Kumamoto University, Kumamoto, Japan
article info
Article history:
Received 9 May 2015
Accepted 12 May 2015
Available online 22 May 2015
Keywords:
Central blood pressure
Pulse wave velocity
Non-invasive measurement
Increased pulse wave velocity (PWV) is associated with incidence of
stroke and coronary diseases, independent of other cardiovascular risk
factors [1–3]. Therefore, the measurement of PWV is recommended in
many current guidelines for the management of hypertensive patients
[4,5]. Recently, we constructed a novel mathematical transformation
function (TF) for central blood pressure (CBP) values estimated by
non-invasive oscillometric blood pressure (BP) measurements [6].In
the present study, we reconstructed TF in coronary artery disease
(CAD) patients, who have different arteriosclerotic characteristics
from healthy subjects [7]. Furthermore, we examined whether there is
association of PWV with estimated CBP and pulse pressure (PP), obtain-
ed by new constructed TF in CAD patients.
We recruited 70 consecutive CAD patients (male: n = 54 [77%] and
female: n = 16 [23%], average: 70.7 ± 8.6 years old), who were referred
to Kumamoto University Hospital and diagnosed by coronary angiogra-
phy (CAG). The study protocol was in agreement with the guideline of
the ethical committee of Kumamoto University, and written informed
consent was obtained from each patient or the family of the subject.
PWV values in CAD patients were measured on admission using a de-
vice for PWV/ABI Form (Omron Colin Co., Ltd., Tokyo, Japan). The meth-
od of PWV measurements was reported previously [8].
During heart catheterization, we measured CBP and constructed TF
as reported previously [6]. Briefly, either a 5 or 6 French Judkins-type
catheter (Togo Medikit, Hyuga, Japan) was placed into the ascending
aorta of the patients, and the CBP was measured and recorded prior to
the initial CAG and administration of any cardiovascular agents. Simul-
taneously with the measurement of CBP by a catheter, we wrapped a
cuff around the left upper arm of supine-positioned patients and mea-
sured the brachial BP oscillometrically using a Pasesa AVE-1500 (Shisei
Datum, Tokyo, Japan). We also measuredan arterial velocity pulse index
(AVI) [6] and an arterial pressure-volume index (API) [9] in CAD
patients, and obtained TF between the invasive CBP values and non-
invasive oscillometric BP values in each patient. We made a correlation
matrix to investigate the correlation among several independent
variables. The independentvariables, which hadsignificant correlations
with aortic systolic BP (AoSBP) were age, systolic BP (= brachial BP,
PSBP), diastolic BP (PDBP), AVI and API values obtained in this matrix.
To examine multiple regression equation, we used AoSBP as a depen-
dent variable and adopted the five above-mentioned variables as inde-
pendent variables. We also adopted aortic pulse pressure (AoPP) as a
dependent variable for the five independent variables: age, PSBP,
pulse pressure (PPP), AVI and API. Using these statistical analyses, we
obtained intercepts and coefficients for each independent variable and
constructed the following formulas: estimated central SBP (eCSBP) =
0.1152 ∗age + 0.7512 ∗PSBP + 0.3095 ∗PDBP + 0.1884 ∗AVI +
0.4001 ∗API −0.1105, estimated central PP (eCPP) = 0.1496 ∗age +
0.1088 ∗PSBP + 0.7312 ∗PPP + 0.2163 ∗AVI + 0.3649 ∗API −
12.3859. Data, analyzed using the method by Bland and Altman, re-
vealed good agreement between AoSBP and eCSBP (mean difference:
0.010 ± 9.255) and between AoPP and eCPP (mean difference:
−0.001 ± 8.735) without any systematic bias (Fig. 1A). In addition,
both correlations were not statistically different (r = −0.222, p =
0.065 and r = −0.219, p = 0.068, Fig. 1A upper left panel and upper
right panel, respectively), indicating no statistical difference between
both methods. Thus, we clearly demonstrated the accuracy of eCSBP
and eCPP values calculated by TF of conventional non-invasive
oscillometric BP measurements. Moreover, the estimated CSBP and
CPP were significantly and strongly correlated with baPWV values
(r = 0.51, p b0.001 and r = 0.48, p b0.001, respectively, Fig. 1B
lower panel).
Augmentation index (AI) is also known to be an index of indicating
vascular stiffness [10]. This tonometry method generally needs to mea-
sure BP pulse wave from body surface, so it is required to detect artery
positionsaccurately and to press arteries which enable to make slightly
IJC Heart & Vasculature 8 (2015) 52–54
⁎Correspondin g author at: Department of Cardio vascular Medicine, Kumamoto
University Graduate School of Medical Sciences, 1-1-1 Honjo, Kumamoto 860-8556,
Japan. Tel./fax: +81 96 373 5175.
E-mail address: eyamamo@kumamoto-u.ac.jp (E. Yamamoto).
http://dx.doi.org/10.1016/j.ijcha.2015.05.004
2352-9067/© 2015 The Authors. Published by Elsevier Ireland Ltd. This is an open access article under theCC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Contents lists available at ScienceDirect
IJC Heart & Vasculature
journal homepage: http://www.journals.elsevier.com/ijc-heart-and-vasculature

flat position without occlusion of arteries. The tonometry methods are
not always easy, and are prone to examiner-dependent manner. In
this study, hence, we proposed new TFs estimating accurate CBP by
oscillometric measurements, which have less measurement errors de-
pendent on the examiner. Moreover, AI is generally influenced by
aging, and it is less significant to monitor in the elderly [11]. Because
the average age of patients in this study was 71 years old, AIs of these
patients have possibility to reach a plateau. Hence, we further examined
13 relatively younger patients (less than 60 years old; male: n = 9
[69%]; average: 52.4 ± 10.5 years old), and applied TFs in relatively
younger patients to examine the accuracy of these TFs. As a result,
both estimated CSBP and CPP were significantly and strongly correlated
with AoSBP and AoPP respectively (r = 0.86, p b0.001 and r = 0.84,
pb0.001, respectively, figures not shown) also in these patients. Thus,
we demonstrated the accuracy of estimated CSBP and CPP values, inde-
pendent of aging. Furthermore, the brachial BP, aortic BP and eCSBP
were 139.71 ± 20.5 mm Hg, 153.9 ± 22.3 mm Hg, and 153.9 ±
20.3 mm Hg, respectively, and these associations with baPWV were
shown in Table 1. The associations of PWV with eCBP and eCPP were
stronger than those with other BP parameters.
(mmHg)
(mmHg)
(mmHg)
(mmHg)
-30
-20
-10
0
10
20
30
50 100 150 200 250 050 100 150 200
-30
-20
-10
0
10
20
30
mean
0.010
-1.96SD
-18.130
+1.96SD
18.150
mean
-0.001
-1.96SD
-17.121
+1.96SD
17.119
Average of two measurements Average of two measurements
Difference
Difference
Fixed error Proportional error
Difference of mean 95% CI
Existence of
error
Correlation
coefficient
P-value
Existence
of error
b-a 0.010 -2.197 , 2.217 No -0.222 0.065 No
d-c -0.001 -2.084 , 2.082 No -0.219 0.068 No
95% CI, confidence interval.
a, AoSBP ; b, eCSBP ; c, AoPP ; d, eCPP.
40
60
80
100
120
140
160
40 60 80 100 120 140 160
eCPP
AoPP
r=0.91, p<0.001
100
120
140
160
180
200
100 120 140 160 180 200
eCSBP
AoSBP
r=0.91, p<0.001
(mmHg)
(mmHg)
(mmHg)
(mmHg)
800
1300
1800
2300
2800
3300
40 60 80 100 120 140 160
baPWV
eCPP
r=0.48, p<0.001
800
1300
1800
2300
2800
3300
100 120 140 160 180 200
baPWV
eCSBP
r=0.51, p<0.001 (cm/sec)
(mmHg)
(cm/sec)
(mmHg)
A
B
Fig. 1. The correlationsof estimated CBP with AoBP and baPWV Panel Ashows Bland–Altmanplots between AoSBP and eCSBP (upper left panel), and AoPP and eCPP (upper right panel).
B upper panelshows the correlations between estimatedCSBP and AoSBP(upper leftpanel), and between estimatedCPP and AoPP (upper rightpanel). Blower panel shows the correlations
between estimated CSBP and baPWV (lower left panel), and between estimated CPP and baPWV (lower right panel). CBP; central blood pressure, AoBP; aortic blood pressure, baPWV;
brachial-ankle pulse wave velocity, CSBP; central systolic blood pressure, AoSBP; aortic systolic blood pressure, CPP; central pulse pressure, AoPP; aortic pulse pressure.
53D. Sueta et al. / IJC Heart & Vasculature 8 (2015) 52–54

Increased CBP causes vascular wall stress in peripheral vessels, such
as the cerebral, coronary and renal arteries, and accelerates atheroscle-
rosis in these arteries, resulting in various cardiovascular diseases. As
described above, accumulating clinical evidence showed a close associ-
ation between CBP and the occurrence of cardiovascular diseases in CAD
and other vascular diseases [12,13]. Because direct CBP measurements
are invasive procedures using a catheter, it is very useful to measure
CBP in CAD patients precisely and non-invasively demonstrated in this
study for risk stratification of CAD. Furthermore, PP, as well as PWV, is
associated with adverse cardiovascular events in CAD patients [10].
This study demonstrated that not only eCSBP but also eCPP had strong
correlation with PWV, indicating the accuracy eCPP values calculated
by new TF in CAD patients. Moreover, there were strong and significant
associations of PWVwith eCSBP and eCPP, suggesting the clinical signif-
icance of estimated CBP by TF, which we firstly constructed.
In conclusion, the associations between PWV and the BP parameters
were calculated by usingnew reconstructedTF, indicating the validity of
these TFs in CAD patients.
Funding sources
None.
Potential conflict of interest
None.
Acknowledgments
We would like to thank Shin-ichiro Tatae, all paramedical staff,
and all medical secretaries for their kind support during this study.
We would like to thank Kazuo Watanabe in the Japan Medical Fund
Corporation, Tokyo, Japan, for his technical support in the mea-
surements of the equations.
References
[1] Vlachopoulos C, Aznaouridis K, Stefanadis C. Prediction of cardiovascular events and
all-cause mortality with arterial stiffness: a systematic review and meta-analysis.
J Am Coll Cardiol 2010;55:1318–27.
[2] Vlachopoulos C, Aznaouridis K, Terentes-Printzios D, Ioakeimidis N, Stefanadis C.
Prediction of cardiovascular events and all-cause mortality with brachial-ankle
elasticity index: a systematic review and meta-analysis. Hypertension 2012;
60:556–62.
[3] Masugata H, Senda S, Yoshikawa K, Yoshihara Y, Daikuhara H, Ayada Y, et al. Rela-
tionshipsbetween echocardiographic findings, pulse wavevelocity, and carotid ath-
erosclerosis in type 2 diabetic patients. Hypertens Res 2005;28:965–71.
[4] ManciaG, Fagard R, Narkiewicz K, Redon J,Zanchetti A, Bohm M, etal. 2013 ESH/ESC
Guidelines for the management of arterial hypertension: the TaskForce for the man-
agementof arterial hypertension of the EuropeanSociety of Hypertension (ESH) and
of the European Society of Cardiology (ESC). J Hypertens 2013;31:1281–357.
[5] Shimamoto K, Ando K, Fujita T, Hasebe N, Higaki J, Horiuchi M, et al. The Japanese
Society of Hypertension Guidelines fo r the Management of Hypertension
(JSH 2014). Hypertens Res 2014;37:253–390.
[6] Sueta D, Yamamoto E, Tanaka T, Hirata Y, Sakamoto K, Tsujita K, et al. The accuracy
of central blood pressure waveform by novel mathematical transformation of non-
invasive measurement. Int J Cardiol 2015;189:244–6.
[7] Hata J, Kiyohara Y. Epidemiology of stroke and coronary artery disease in Asia. Circ J
2013;77:1923–32.
[8] Yamashina A, Tomiyama H, Takeda K, Tsuda H, Arai T, Hirose K, et al. Validity, repro-
ducibility, and clinicalsignificance of noninvasivebrachial-ankle pulse wave velocity
measurement. Hypertens Res 2002;25:359–64.
[9] Komine H, Asai Y, Yokoi T, Yoshizawa M. Non-invasive assessment of arterial
stiffness using oscillometric blood pressure measurement. Biomed Eng Online
2012;11:6.
[10] Goto T, Ohte N, Fukuta H, Wakami K, Tani T, Kimura G. Relationship between effec-
tive arterial elastance, total vascular resistance, and augmentation index at the as-
cending aorta and left ventricular diastolic function in older women. Circ J 2013;
77:123–9.
[11] McEniery CM, Yasmin, Hall IR, Qasem A, Wilkinson IB, Cockcroft JR, et al. Normal
vascularaging: differential effectson wave reflection and aortic pulse wavevelocity:
the Anglo-Cardiff Collaborative Trial (ACCT). J Am Coll Cardiol 2005;46:1753–60.
[12] Williams B, Lacy PS, Thom SM, Cruickshank K, Stanton A, Collier D, et al. Differential
impact of blood pressur e-lowering drugs on central aortic pressure and clinical
outcomes: prin cipal results of th e Conduit Artery F unction Evaluation (CAFE)
study. Circulation 2006;113:1213–25.
[13] Roman MJ, Devereux RB, Kizer JR, Lee ET, Galloway JM, Ali T, et al. Central pressure
more strongly relates to vascular disease and outcome than does brachial pressure:
the Strong Heart Study. Hypertension 2007;50:197–203.
Table 1
The relationships among brachial,aortic BP and eCSBP, and between baPWV andthese BP
parameters.
Correlations r value p value
Brachial BP vs. eCSBP 0.99 p b0.01
Aortic BP vs. eCSBP 0.91 p b0.01
eCSBP vs. baPWV 0.51 p b0.01
Brachial BP vs. baPWV 0.51 p b0.01
Aortic BP vs. baPWV 0.48 p b0.01
BP; blood pressure, baPWV; brachial-ankle pulse wave velocity, eCSBP; estimated central
systolic blood pressure.
54 D. Sueta et al. / IJC Heart & Vasculature 8 (2015) 52–54