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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4048_Библиотеки_им_академика_М_И_Перельмана
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201
Fig. 5.24. The accuracy of predicting adverse outcomes by blood flow velocity in
the proximal portions of the left coronary artery.
ROC analysis did not provide a significant distribution of patient velocity in the
middle portions of the left coronary artery to predict adverse outcomes.
In multivariate analysis, only the maximum velocity in the proximal portions of the
left coronary artery (OR 1.04, 95% CI 1.02–1.05, p<0.0001) determined the
cumulative point of all adverse outcomes.
5.4.5.5. The role of revascularization in changing the prognosis of patients with
high blood flow velocities in the left coronary artery.
In the group under study, revascularization was made in 184 patients – the
"Surgery" group (45% of the total patients in three groups), 79 (43%) – coronary
artery bypass grafting, 97 (53%) – percutaneous coronary intervention with
stenting, and 8 (4%) patients underwent both procedures. Accordingly, 173
patients were without percutaneous intervention or coronary artery bypass
grafting – the "ODT" group.
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Comparative characteristics of patients with and without revascularization are
given in Table 5.6.
Table 5.6.
"Surgery" group
N=184
"ODT" Group
N=173
P value
Age (years)
61,3±9
63,3±13
NS
Sex (M/F)
138/46
101/72
0.0008
BMI (kg/m2)
28,8±4
28,5±5
NS
Hypertension
157 (85%)
141 (82%)
NS
Previous CAD
107 (58%)
68 (39%)
0.0005
Previous PCI
60 (33%)
30 (17,4%)
0.001
Diabetes mellitus
37 (20%)
19 (11%)
0.02
Previous MI
82 (45%)
39 (23%)
0.00001
Echocardiography
EF, %
60,5 ±10
61,4±11
NS
EDV, ml
109±37
110±35
NS
Exercise test
Maximal HR
(beats/min)
103±13
114±22
0.000001
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Exercise capacity
(W)
65±24
81±37
0.00003
Maximal blood
pressure, mmHg
166±24
177±26
0.002
Coronary artery velocity at rest
Max velocity in
LM/proximal
LAD/proximal LCx
101±29
100±33
NS
Max velocity in
middle LAD/middle
LCx
92±43
89±27
NS
LM – left main artery; pLAD – proximal portion of left anterior descending artery; pLCx –
proximal portion of left circumflex artery; mLAD – middle portion of left anterior descending
artery; mLCx – middle portion of left circumflex artery.
Deaths were recorded in 17 cases in the entire study sample (4.7%), in the
"Surgery", "ODT" groups and in the control group – 1.6; 8.1 and 0%, respectively
(p1<0.009, p2<0.03; p1 – differences in the "Surgery" and in the control group,
p2 – differences in the "ODT" and in the control group).
Death/acute coronary events were observed in 27 patients in the "Surgery", "ODT"
groups and in the control group in 4.9, 11.0 and 0%, respectively (p1<0.05,
p2<0.006; p1 – differences in the "Surgery" and in the control group, p2 –
differences in the "ODT" and in the control group).
Using the Kaplan-Meier method, the curve of the combined point "death/acute
coronary events" of patients of all studied groups was determined – Fig. 5.25.
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Fig. 5.25 Kaplan-Meier curves of survival of patients with altered coronary blood
flow depending on myocardial revascularization.
5.5 Discussion
In this part of the study, we obtained prognostic results of changes in coronary
blood flow detected during echocardiography. High velocity parameters in the
proximal portions of the left coronary basin were associated with a subsequent
high risk of adverse events over a short follow-up period of 10.5 months. Mortality
for this averaged period was recorded in 6.4% of patients only in the group of
patients with high velocities in the proximal portions of the left coronary artery. In
terms of death/acute coronary events, 10% of patients in this group reached the
endpoint, and in patients with high velocities in the middle portions of the studied
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205
arteries only in 1.11% of cases the achievement of the combined death/acute
coronary events point was recorded. It is known that with the chances of
developing acute coronary syndrome or death over 3% within a year, patients with
coronary artery disease are at high risk [41]. In our study, the risk of developing
such adverse outcomes was three times higher within 10.5 months, with 25% of
them reaching the death/acute coronary syndrome control point within the next 62
days. Therefore, ultrasound of the coronary arteries among all patients referred for
echocardiography allows to identify a group at risk of death/ACS with a
probability 3 times higher than the high risk limit value in the coming months. In
the control group during the observation period, the incidence of death and
death/ACS was 0 (0%) patients. It should be noted that the patients of the control
group were comparable with the patients of the studied groups in terms of age and
the main echocardiographic parameters, including the prognostically important
parameter of the left ventricular ejection fraction. Attention is drawn to the great
prognostic significance of blood flow velocities in comparison with the left
ventricular ejection fraction. This is due to several factors. First, the left ventricular
ejection fraction plays a serious prognostic role only when it is reduced. In patients
before myocardial infarction with significant narrowing of the coronary arteries,
the ejection fraction at rest is in the normal range in most cases, although the
immediate prognosis of adverse outcomes may be poor. It is the change in blood
flow with narrowing of the arteries, which can be measured directly with
echocardiography, that indicates the immediate threat to the patient. Therefore,
with a normal ejection fraction, but abnormal blood flow in the heart arteries, the
adverse prognosis for the patient seems logical. Second, a small decrease in the
ejection fraction is more important for a distant rather than a direct forecast. In our
study, patients were followed up for a short period of time.
To date, studies associating high rates of coronary blood flow with the
development of further adverse coronary events and the effect on the prognosis of
such patients have appeared in the available literature only in the last year. To date,
in the available literature, simultaneously with our study, only one work has been
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published on this topic: a single-center analysis of a cohort of patients, Morofuju T.
et al. [92]. However, this work has serious limitations imposed by the retrospective
design of that study. Nevertheless, based on a large sample of patients, the authors
showed that high blood flow velocities in the proximal portion of the left main
coronary artery and the anterior descending artery are associated with death and
are an independent predictor of adverse outcomes (myocardial infarction, heart
failure, sudden cardiac death in the period up to 6.3 years on average). The limit
values obtained in this study for predicting further adverse events cannot be
compared with the work of Morofuju T. et al., since they used not the peak, but
the average velocity in the LAD. The above paper still did not analyze the effect of
myocardial revascularization on further adverse events in groups of patients with
high coronary blood flow velocities visualized using transthoracic ultrasound.
In this study, it was possible to prove a reliably favorable effect of
myocardial revascularization and its positive impact on the survival rate and
incidence of acute coronary events in patients with altered coronary blood flow
according to ultrasound data. Death was recorded in 1.6% vs. 8.1% vs. 0%,
p1<0.005, in the "Surgery" group vs. "ODT" group vs. the control group,
respectively. Death/acute coronary events – 4.9% vs. 11.0% vs. 0%, p1 <0.04, in
the "Surgery" group vs. "ODT" group vs. the control group, respectively.
In this study, the groups with and without revascularization were not randomized,
no significant differences were obtained when comparing the baseline
characteristics of these groups in terms of such parameters as age, body mass index,
hypertension, left ventricular ejection fraction, as well as parameters of maximum
blood flow rates in the coronary arteries. However, according to its clinical
characteristics (proven coronary artery disease, previous myocardial infarction,
diabetes mellitus), the group with revascularization was more severe, but the
survival rate of patients in the "Surgery" group was significantly higher, and the
number of acute coronary events was lower.
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Despite the fact that all patients were offered further follow-up, followed by
coronary angiography and possible myocardial revascularization, almost half of the
patients were not revascularized, which is partially due to the absence of symptoms
of coronary artery disease and patients' refusal to be further diagnosed. While in
group 1, patients more often had proven coronary artery disease and previous
myocardial infarction, and were ready for cardiac surgery.
CAD may not have specific symptoms, and the first manifestation of the
disease is often myocardial infarction or death, and the method of transthoracic
ultrasound diagnostics of coronary blood flow can help to identify changes in
coronary blood flow during routine echocardiography, and the data obtained, given
their high prognostic value, can be considered an indication to coronary
angiography with further revascularization of the artery concerned.
Limitations
There are some limitations in the work. The groups were not subdivided into
types of revascularization (coronary artery bypass grafting, percutaneous coronary
intervention with stenting) due to the small number of patients in the subgroups.
Further prospective study is required to compare the types of revascularization and
to determine their effect on the prognosis in patients with high coronary blood flow
velocities.
Patients were not randomized in the "Surgery" group, the "ODT" group for ethical
reasons, which, in theory, could affect the result. However, the groups did not
differ n terms of significance by baseline echocardiographic characteristics, and the
group with revascularization was significantly more severe in terms of clinical
parameters. A study in which a part of patients will be randomized to a group
without revascularization seems to be ethically questionable in the future as well.
This is due to a proven severe prognosis in patients with pathologically altered
blood flow in the coronary arteries, with a high probability of significant stenosis
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of these arteries, which requires surgical correction according to the current
recommendations.
We used absolute values of velocities, and not the ratio of pretenotic/stenotic blood
flow velocity. Doppler sonography method is angle-dependent. However, despite
using only absolute values of coronary blood flow velocities, a strong relationship
with further clinical outcomes was shown prospectively.
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Conclusions
1. A significant positive correlation was found between the value of the maximum
velocity in the left main coronary artery / proximal portion of the left anterior
descending artery and the end-diastolic volume of the left ventricle at rest r =
0.20, p = 0.024, and a positive stress echocardiographic test r = 0.35, p<0.0001,
and the peak exercise ejection fraction r = -0.39, p<0.0001.
2. A significant positive correlation was determined between the coronary blood
flow velocities according to ultrasound data and the percentage of coronary
artery stenosis in the corresponding segment – r=0.52; p<0.0000001.
3. The limit value blood flow velocity in the left main coronary artery to determine
≥50% stenosis is 67 cm/s; sensitivity – 69%, specificity – 89%, accuracy – 79%,
p<0.0004. Velocity of coronary blood flow in the left main coronary artery over
67 cm/s, according to ultrasound, may be an indication for coronary
angiography.
4. A velocity of more than 97 cm/s in the proximal portions of the left coronary
artery is a predictor of death and acute coronary events with an accuracy of 76%,
p<0.001. Patients with a blood flow velocity greater than 70 cm/s in the
proximal portion of the left coronary artery have a risk of death/acute coronary
events of 10% (95% CI 7-13; p<0.0001) within 10.5 months.
5. It was possible to prove a reliably favorable effect of myocardial
revascularization on the survival rate and incidence of acute coronary events in
patients with altered coronary blood flow according to ultrasound data. Death,
death/ acute coronary events occur less frequently during surgical tactics in
patients with blood flow velocities over 70 cm/s in the proximal portion of the
left coronary artery, p<0.04.
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Practical Guidelines
1. It is recommended to additionally measure the coronary blood flow velocity
during routine coronary angiography at least in the proximal portions of the left
coronary artery.
2. Before stress echocardiography, it is advisable to examine the flow velocity in
the main/proximal portions of the left coronary artery. If the blood flow velocity
in these portions is more than 70 cm/s, it is advisable to abandon the provocative
stress test in favor of invasive coronary angiography.
3. When detecting coronary blood flow velocities above 70 cm/s in the proximal
portions of the left coronary artery according to ultrasound diagnostics, it is
recommended to treat the coronary artery disease even in the absence of a
typical clinical pattern.
4. Surgical revascularization of the myocardium in the blood supply zone of this
coronary artery is recommended for patients with increased coronary blood flow
velocities more than 70 cm/s in the proximal portions of the left coronary artery,
along with optimal drug therapy.
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