MINISTRY
OF EDUCATION AND TRAINING
MINISTRY OF
DEFENCE
108 INSTITUTE OF CLINICAL MEDICAL AND
PHARMACEUTICAL SCIENCES
--------------------------------------------------------
NGUYEN THITHANH TRUNG
STUDY OF CLINICAL CHARACTERISTICS AND LEFT
VENTRICULAR DYSSYNCHRONY IN PATIENTS AFTER
ACUTE MYOCARDIAL INFARCTION USING GATED-SPECT
IMAGING
Specialty: INTERNAL CARDIOVASCULAR
CODE: 62.72.01.41
DOCTOR DISSERTATION
Ha Noi - 2020
THIS DISSERTATION WAS COMPLETED AT
108 INTSTITUTE OF CLINICAL MEDICAL AND
PHARMACEUTICAL SCIENCES
Scientific supervisors:
1. Associate Professor. Dr.Le Ngoc Ha
2. Associate Professor. Dr. Pham Thai Giang
Reviewers:
1. Associate Professor. Dr. Dinh Thi Thu Huong
2. Associate Professor. Dr. Luong Cong Thuc
3. Associate Professor. Dr. Tran Van Riep
The dissertation was examined and assessed by Institutional Scientific
Council at 108 Institute of Clinical medical and Pharmaceutical
sciences at ..... on ......, ......
The disse rtation can be found at:
1. National Library
2. Library of 108 Institute of Clinical medical and
Pharmaceutical sciences
1
INTRODUCTION
1. Necessity of the study
Left ventricular dyssynchrony is one of the consequences of coronary
artery disease. After early myocardial infarction, 56.0% and 61.0% of
patients had left ventricular dyssynchrony based on evaluation of Tissue
Doppler Imaging. According to Ko (2009), the rate of patients with left
ventricular dyssynchrony after myocardial infarction is generally 32.6%.
Left ventricular dyssynchrony is closely associated with heart
failure,increasing major adverse cardiovascular events (MACE) as well
as mortality in patients after myocardial infarction. Following 197
patients with myocardial infarction, Pazhenkottil (2011) showed that the
rate of patients with MACE in the group with left ventricular
dyssynchrony was much higher than that in the group without left
ventricular dyssynchrony (62.9% compared with 24.7%) and proved that
left ventricular dyssynchrony is one of the three independent predictors
of MACE.
There have been many methods for assessing left ventricular
dyssynchrony such as: electrocardiogram, Tissue Doppler ultrasound of
cardiac muscle tissue, 3D ultrasound, and myocardial perfusion scan, etc.
in which myocardial perfusion imaging proved to be superior in
assessing left ventricular dyssynchrony by its accuracy and objectivity.
In Vietnam, some studies have applied Gated-SPECT to evaluate
residual myocardial ischemia, myocardial infarction scars, cardiac wall
motion and cardiac function. Several domestic studies published on the
use of electrocardiography, Tissue Doppler ultrasound in evaluating left
ventricular dyssynchrony. However, there have not been any studies to
assess the dyssynchrony performed with myocardial perfusion scan by
Gated-SPECT method with specialized software for analyzing left
ventricular dyssynchronyin patients after myocardial infarction.
Therefore, the study of this issue is controversial, scientific and brings
about a lot of benefits for physicians in the prognosis and treatment of
patients after myocardial infarction.
2. Meanings of the study
The use of myocardial perfusion imaging (MPI) in assessing left
ventricular dyssynchrony will help overcome some disadvantages of
Tissue Doppler ultrasound methods. For example, MPI could assess 17
myocardial regions simultaneously including the cardiac apex, whereas
the Tissue Doppler ultrasound can not assess the dyssynchrony at the
heart apex region, and this method has an increase in the unit. This
method of MIP, using degrees to assess, also corrects errors when
2
evaluating patients with different heart rates. In addition, MPI also
assesses the status of residual myocardial ischemia, cardiac wall motion,
heart function, cardiac muscle survival status. Therefore this method
helps clinicians predict and offer better treatments for patients.
3. Objectives of the study
- To investigate some clinical, laboratory characteristics and left
ventricular dyssynchrony using Gated-SPECT imaging in patients after
acute myocardial infartion.
- To assess the relationship between left ventricular dyssynchrony
on Gated-SPECT imaging and some clinical features, echocardiography
in patients after acute myocardial infarction.
4. Structure of the disse rtation
The dissertation consists of 128 pages (excluding references and
indexes) including 4 main chapters: Introduction: 02 pages, Chapter 1 –
Literature review: 36 pages, Chapter 2 - Subjects and methodology: 19
pages, Chapter 3 –Research results: 32 pages, Chapter 4 - Discussions:
32 pages, Conclusion and recommendations: 03 pages. The dissertation
has 29 tables, 13 schemes and figures, 20 illustration, 157 references
with 17 in Vietnamese and140 in English.
CHAPTER I: LITERATURE REVIEW
1.1. Lesions after myocardial infarction
Myocardial infarction (MI) is a condition when atherosclerosis
blocks the coronary arteries, stop supply of blood and oxygen to the
heart muscle. Although there have been many advances in diagnosis,
treatment and monitoring, myocardial infarction remains a challenging
issue for the health sector. The more patients rescued from acute
myocardial infarction, the more patients have to accompany the post-MI
disorders such as residual myocardial ischemia, left ventricular
remodelling, left ventricular dyssynchrony, arrhythmia, heart failure, re-
infarction.
1.2.Cardiac dysynchrony
In cardiology, dyssynchrony is the phenomenon in which the different
parts of the heart contract in a non-rhythmic physiological sequence,
leading to a decrease in ejection efficiency.Left ventricular mechanical
dyssynchrony is the differences in the timing of contraction or relaxation
between different myocardial segments or the contraction of the heart
muscle areas that are delayed in the systole.Mechanical
dyssynchronyusually appears in the late stages of some heart conditions,
associated with hypertrophy and left ventricular dysfunction. Left
3
ventricular mechanical dyssynchrony is particularly common after
myocardial infarction. Left ventricular dyssynchronyreduces the ejection
fraction, aggravates heart failure, and increases myocardial oxygen
demand, increases left ventricular remodelling. The detection of left
ventricular dyssynchrony also plays an important role in the designation
and prognosis of the treatment success of resynchrony.
1.2.1. Methods for evaluating left ventricular dyssynchrony
Routine ECG
This method is simple, easy to implement and can be implemented in all
health facilities. However, it is only possible to assess the electrical
dyssynchrony and does not reflect the mechanical dyssynchrony.
According to the North American Heartbeat Association and the
American Society of Echocardiography when PR≥160 ms, QRS≥120 ms
is considered to have electrical dyssynchrony and this is a criterion for
the selection of patients after MI designated as cardiac resynchronization
therapy (CRT).
M-mode echocardiography
This method can only assess the dyssynchrony of the ventricular
septum and left posterior ventricle by measuring the maximum
difference in time of inoculation of the ventricular septum and left
posterior ventricular wall. When this index is ≥130 ms, it is an indicator
to evaluate intraventricular dyssynchrony.
Tissue Doppler imaging
Pulse-Doppler Ultrasound: This method assesses by measuring
the time interval Ts is the time from the beginning of the QRS complex
to the start of the S wave or to the S wave peak of each region, then
based on the difference in Ts of the myocardial regions, it will evaluate
th level of left ventricular dyssynchrony. If the Ts difference between the
wall and lateral wall is>65 ms, there is a left ventricular dyssynchrony.
Ultrasound Tissue velocity imaging (TVI):In this method, each
cross section will assess simultaneously the movement of two or more
cardiac muscle regions in the same cycle. By visual observation, the time
when the peak velocity of two regions overlap or close to each other is
considered as the opposite two regions contracting synchronously and
vice versa.
Tissue synchronization imaging (TSI):The ultrasound can
automatically calculate the time difference to reach the maximum
systolic wave velocity of the opposite myocardial regions and the 12
myocardial regions as well as the standard deviation of the time to reach
the maximum systolic wave velocity of 12 cardiac muscle regions (Ts -