Download LEFT VENTRICULAR DIASTOLIC FUNCTIONAL STATUS AFTER

Acta Medica Mediterranea, 2016, 32: 1965
LEFT VENTRICULAR DIASTOLIC FUNCTIONAL STATUS AFTER CORONARY ARTERY BYPASS
GRAFTING
NAHID SALEHI*, ALIREZA RAI*, MOHAMMAD-RAZA SAIDI*, AZAM KIANI*, PARISA JANJANI*,**, HOOMAN TADBIRI***
*
Department of Cardiology, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran - **Student of PhD
Psychology, faculty of social sciences, Razi University, Kermanshah, Iran - ***Iran University of Medical Sciences, Tehran, Iran
Abstract
Background: Improving or deteriorating effects of cardiac revascularization on left ventricular diastolic dysfunction especially concurrent with left ventricular systolic dysfunction is still controversial.
Objectives: We aimed to compare diastolic functional status after coronary artery bypass grafting (CABG) with the baseline in
patients with known coronary artery disease.
Methods: Sixty consecutive patients with known coronary artery disease according to coronary angiography findings who
were candidates for elective CABG were enrolled in a before-after interventional study. Before and also three months after CABG,
the parameters of left ventricular diastolic function were measured by Doppler and tissue Doppler echocardiography by the Paired t
test with considering p-value of less than 0.05 as significant.
Results: The mean±SD age of the participants was59.6±8.7 years (range: 46-78 years) and 75% were men. With regard to the
changes in echocardiography parameters, significant improvement in mean DT index (from 224±54 msec to 192±42 msec, p <
0.001), IVRT (from 104 ± 22 msec to 85±13 msec, p < 0.001), E/Ea Ratio (from 11.19±3.74 to 9.30±2.67, P<0.001), and LV ejection
fraction (from 47.59±6.94% to 49.36±7.77%, P=0.007) was observed. Among all subjects, 56.6% experienced improvement in cardiac diastolic function index with more improvement in men than in women, non-diabetics compared with diabetics, normotensive
compared with hypertensive individuals (57.1% versus 36.6%), and nonsmokers than in smokers. Younger patients also experienced
more improvement in diastolic function index than the patients older than 60 years, however the improvement of these functional
parameters remained independent to the number of involved coronary vessels.
Conclusions: Improvement of left ventricular diastolic function can be achieved about three months after CABG surgery, independent to the severity of coronary artery diseas
Keywords: Ventricular, Systolic, Diastolic, Heart failure.
Received April 30, 2016; Accepted July 02, 2016
Introduction
Left ventricular (LV) diastolic dysfunction that
precedes ventricular systolic function impairment
can be developed following myocardial ischemia
and progress to chronic heart failure leading to poor
prognosis (1,2). This abnormality is the result of
inhibiting uptake of sarcoplasmatic reticulum calcium, left ventricular aneurism, ventricular chamber
stiffness, and change in ventricular remodeling(3-5).
Even, LV diastolic function seems to be more sensitive to cardiac injury than systolic dysfunction(6,7).
Several studies have demonstrated a significant long-term improvement in LV diastolic function assessed by tissue Doppler imaging following
cardiac revascularization(8). Moreover, some other
studies have shown that LV diastolic dysfunction
might persist early after cardiac surgeries even for
up to one month after operation(9). These changes
seems to be directly associated with reduced LV
systolic dysfunction characterized by lowering LV
ejection fraction, cardiopulmonary bypass time,
number of grafts used and even severity and extension of coronary involvement(10,11).
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The abnormal changes in LV diastolic dysfunction especially concurrent with LV systolic
dysfunction may be interestingly found following
coronary artery bypass grafting (CABG). However,
LV diastolic functional changes following cardiac
revascularization have not been well defined. We
aimed to compare diastolic functional status after
CABG with the baseline (before surgery) in
patients with known coronary artery disease.
Patients and methods
Sixty consecutive patients with known coronary artery disease according to coronary angiography findings who were candidates for elective
CABG were enrolled during 2013-2014 at Imam
Ali Heart Center in a before-after interventional
study. The included subjects all had LV ejection
fraction more than 30% with some degrees of LV
diastolic dysfunction.
In this regard, those with known causes for LV
diastolic dysfunction such as uncontrolled hypertension (resting SBP/DBP>140/90 mmHg), hypertrophic cardiomyopathy, LV hypertrophy, increased
serum creatinine level, cardiac blocks, atrial fibrillation, pace maker implantation, or history of
CABG were not included. The research protocol of
this study was approved by the research and ethics
committees of Kermanshah University of Medical
Sciences. On admission, baseline characteristics
including demographics, medical history, and oral
medications were collected through interviews and
recorded in medical charts.
Before CABG and according to the American
Society of Echocardiography guidelines, the parameters of left ventricular diastolic function including Isovolumic relaxation time (IVRT), E/A Ratio
of Mitral Inflow Velocity, MVA duration, PVA
duration, PVs/PVd, DT, Ea, and E/Ea were measured by Doppler and tissue Doppler echocardiography in all subjects. All participants underwent
elective CABG by a single surgeon and similar
techniques. Three months after CABG, the echocardiography parameters were reassessed by the same
diagnostic tool. The study endpoint was to assess
the changes in echocardiography parameters of LV
diastolic function after CABG and to compare it
with the baseline.
Results
Results were expressed as mean±standard
deviation (SD) for quantitative variables and were
Nahid Salehi, Alireza Rai et Al
summarized by absolute frequencies and percentages for categorical variables. Continuous variables
were compared using t test, or non-parametric
Mann-Whitney U test, whenever the data did not
appear to have normal distribution or when the
assumption of equal variances was violated across
the groups. Categorical variables were compared
using Chi-square test or Fisher’s exact test when
more than 20% of cells with expected count of less
than 5 were observed. The change in echocardiography parameters after CABG were compared with
the baseline that was assessed using the paired t test
or non-parametric Wilcoxon test. For the statistical
analysis, the statistical software SPSS version 20.0
for windows (SPSS Inc., Chicago, IL) was used. P
values of 0.05 or less were considered statistically
significant.
Baseline Data
The mean±SD age of the participants
was59.6±8.7 years (range: 46-78 years) and 75%
were men.
Female gender
15 (25.0)
Diabetes mellitus
12 (20.0)
Hyperlipidemia
25 (41.6)
Current smoking
15 (25.0)
Hypertension
30 (50.0)
Number of diseased coronary artery
One
5 (8.3)
Two
15 (25.0)
Three
40 (66.7)
Medication
Clopidogrel
50 (83.3)
Aspirin
57 (95.0)
HMG CoA RI
51 (85.0)
Beta Blocker
41 (68.3)
ACE inhibitors
25 (41.7)
Calcium Chanel
Blocker
14 (23.3)
ARB
10 (16.7)
Nitrocontine
20 (33.3)
Hydrochlorothiazide
2 (3.3)
Warfarin
2 (3.3)
Aldacton
2 (3.3)
Lasix
2 (3.3)
Digoxin
2 (3.3)
Table 1: Baseline characteristics of study population.
Left ventricular diastolic functional status after coronary artery bypass grafting
Regarding the cardiovascular risk profile, 50%
were hypertensive, 25% were current smokers,
41.7% had hyperlipidemia and 20% had diabetes
mellitus. With respect to the number of diseased
coronary arteries based on angiography evidences,
8.3% had single-vessel disease, 25% had two-vessel disease, and 66.7% had three-vessel disease
(table 1).
Change In Echocardiography Parameters
With regard to the changes in echocardiography parameters (table 2), mean DT index significantly improved within three months follow-up
time from 224±54 msec to 192±42 msec (p <
0.001), IVRT also reduced significantly from
104±22 msec to 85±13 msec (p < 0.001).
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(47.6% versus 33.3%), normotensive compared
with hypertensive individuals (57.1% versus
36.6%), and nonsmokers than in smokers (69.2%
versus 36.8%). Moreover, of the 15 patients with
LV ejection fraction <45%, the improvement in cardiac diastolic function index was seen only in 4
(26.7%) patients, while this improvement was
found in 30 (66.7%) out of 45 patients with LV
ejection fraction >45%. Younger patients experienced more improvement in diastolic function
index than the patients older than 60 years (72.4%
versus 41.9%), however improvement of these
functional parameters remained independent to the
number of involved coronary vessels (60% in single-vessel disease, 66.7% in two-vessel disease, and
52.5% in three-vessel disease).
Index
Before surgery
After surgery
P-value
DT(msec)
224 ± 54
192 ± 42
< 0.001
IVRT(msec)
104 ± 22
85 ± 13
< 0.001
Total population
E / A Ratio
0.83 ± 0.35
0.85 ± 0.27
0.64
MVA dur / PVA dur
1.13 ± 0.25
1.19 ± 0.23
PVs / PVd
1.45 ± 0.38
Ea ( E' )
Improvement in DFI after CABG
DFI before CABG
Total
Normal
1 grade
2 grades
3 grades
I
28
22
0
0
50
0.158
II
1
4
3
0
8
1.56 ± 0.32
0.096
III
0
0
1
1
2
6.11 ± 1.12
7.49 ± 1.54
< 0.001
Total
29
26
4
1
60
E / Ea Ratio
11.19 ± 3.74
9.30 ± 2.67
< 0.001
Men
LVEF %
47.59 ± 6.94
49.36 ± 7.77
0.007
I
22
17
0
0
39
II
1
3
1
0
5
III
0
0
1
0
1
Total
23
20
2
0
45
I
6
5
0
0
11
II
0
1
2
0
3
III
1
0
0
1
1
Total
6
6
2
1
15
Because we did not have the source of data, we could not
analyze the data and thus obtain the p-values.
Table 2: The change in diastolic functional parameters
after operation compared with before that.
Women
However the change in E/A Ratio remained
unchanged postoperatively (from 0.83±0.35 to
0.85±0.2, P=0.64). Among other indices, MVA
dur/PVA duration (from 1.13±0.25 to 1.19±0.23,
P=0.16), and PVs/PVd (from 1.45±0.38 to
1.56±0.32, P=0.09) remained unchanged.
Following CABG, Ea index (from 6.11±1.12
cm/sec to7.49±1.54 cm/sec, P<0.001), E/Ea Ratio
(from 11.19±3.74 to 9.30±2.67, P<0.001), and LV
ejection fraction (from 47.59±6.94% to
49.36±7.77%, P=0.007) were also significantly
improved.
Change in diastolic function index
With regard to the improvement in cardiac
diastolic function index (table 3), 56.6% of the
patients experienced improvement in this index
with more improvement in men than in women
(40.0% versus 33.3%), non-diabetics than diabetics
Table 3: Improvement in diastolic function index (DFI)
after operation.
Discussion
Previous studies assessing changes in LV diastolic dysfunction following cardiac operations
yielded contradictory findings. Although some
studies showed significant improvement in almost
all parameters of LV diastolic dysfunction after
CABG, some others showed deterioration of LV
diastolic function assessed by tissue Doppler imaging. Researchers also found time- dependent
changes in LV diastolic indices so that early deteri-
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orating LV diastolic function, but long-term decompensated LV diastolic function was observed.
According to these paradoxical results, we attempted to evaluate changes in LV diastolic function
three months after CABG in patients without severe
LV systolic dysfunction. We found improvement in
most LV diastolic functional indices including DT,
IVRT, and E/Ea Ratio. The improvement in LV
diastolic function indices was also parallel to the
increase in LV systolic function assessed by
increase in LV ejection fraction. Regardless of LV
systolic dysfunction, LV diastolic dysfunction is a
serious determinant for cardiac-related mortality
and morbidity(12).
Especially in patients undergoing CABG, the
measurement of some diastolic indices such as LV
diastolic diameters have been shown to be associated with worsen postoperative outcome(13,14). Thus,
assessing improvement or deterioration of LV diastolic function can also help predict long-term outcome in patients undergoing CABG.
In total, our study confirmed improvement of
LV diastolic function 3 months after CABG.
Although early assessment of LV diastolic function
after CABG has shown reducing diastolic functional state, but it seems that the time of 3 months can
be enough for compensating LV surgery-related
diastolic dysfunction. In this regard, previous studies had considered different follow-up times for
assessing LV diastolic function following CABG.
In a recent study by Ashes and colleagues(15), new or
worsened diastolic dysfunction was revealed in
31% of operated patients after cardiopulmonary
bypass. In another recent study by Ferreira et al(16),
the authors showed high risk for diastolic dysfunction early after CABG with higher risk ratio for
women than in men. Castelvecchio et al(17) showed
LV diastolic function in most patients that was significantly dependent to abnormal changes in LV
shape and residual volume.
In a study by Luk’ianov(18) in the elderly, significant improvement in diastolic function of the
left ventricle was found following surgical revascularization of myocardium in advanced age subgroups. Bacior et al (19) also indicated notable
improvement in both LV systolic and diastolic function following CABG independent to the effect on
global right ventricular performance.
Finally, in a study assessing LV diastolic
function by color M-mode Doppler echocardiography(20), improvement in LV diastolic indices was
shown. The contradictory results related to the
Nahid Salehi, Alireza Rai et Al
effects of CABG on LV diastolic indices may be
due to the time points of assessing LV diastolic
function, baseline characteristics of cardiac functional status before surgery such as presence of systolic dysfunction, surgical technique and the use of
cardiopulmonary bypass, severity of coronary
involvement, and even the number of grafts used
intraoperatively.
In conclusion, according to our findings,
although worsening LV diastolic function may
occur early after CABG, it seems that this change
is temporary and thus improvement or compensation of LV diastolic function is predictable about
three months after operation. Thus, the assessment
of LV diastolic function preferably concomitantly
with assessing LV systolic function at different
time points after surgery and with considering preoperative and intraoperative characteristics is essential.
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Corresponding author
HOOMAN TADBIRI
Iran University of Medical Sciences, Tehran
Email: [email protected]
(Iran)
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