3. Luan An Tom Tat - Eng.pdf

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF DEFENCE 108 INSTITUTE OF CLINICAL MEDICAL AND PHARMACEUTICAL SCIENCES NGUYEN DUNG LATE POTENTIALS CHARACTERISTICS AND VENTRICULAR ARRHYTHMIAS IN CHRONIC[.]

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF DEFENCE

108 INSTITUTE OF CLINICAL MEDICAL AND PHARMACEUTICAL SCIENCES

-

NGUYEN DUNG

LATE POTENTIALS CHARACTERISTICS AND

VENTRICULAR ARRHYTHMIAS IN CHRONIC ISCHEMIC

HEART DISEASE PATIENTS

Majors/Speciality: Internal medicine/Internal cardiology

Code: 9720107

SUMMARY OF MEDICAL PhD THESIS

Hanoi – 2023

The thesis was done at:

108 Institute of Clinical Medical and Pharmaceutical sciences

Supervisors:

1 Assoc Prof PhD Pham Thai Giang

2 Assoc Prof PhD Pham Nguyen Son

Reviewers:

1

2

3

This thesis will be presented at the Institute Council at:

108 Institute of Clinical Medical and Pharmaceutical sciences

Day Month Year 20

This thesis can be found at:

1 National Library of Vietnam

2 Library of 108 Institute of Clinical Medical and Pharmaceutical sciences

INTRODUCTION

1 Necessity of the thesis

Chronic ischemic heart disease (IHD) or stable coronary artery disease (CAD) and chronic coronary artery syndrom as Consensus of the European Society of Cardiology 2019 This disease affected about 126 million individuals (1,655/100,000), about 1.72% of the world population, of which about 9 million deaths caused by: arrhythmia, heart failure, or heart attack Arrhythmias, especially ventricular arrhythmias, including ventricular tachycardia, ventricular fibrillation, can cause cardiac arrest, even sudden death

Stratification and risk prediction for ventricular arrhythmias in patients with chronic IHD was important, and late potentials could help predict dangerous arrhythmias and predict cardiovascular disease There were many studies on late potential, but no study on late potential and its association with ventricular arrhythmias in patients with chronic IHD

2 Meaning of the study

The assessment, prediction, and risk stratification would help prevent and treat effectively Late ventricular potential recording was an effective, inexpensive, noninvasive, bedside technique that contributes to risk stratification for dangerous ventricular arrhythmias in patients with chronic IHD

3 Objectives of the study

1 To investigate of clinical, subclinical and late potential characteristics

in patients with chronic IHD

2 To assess the relationship between late potential and clinical characteristics, subclinical and ventricular arrhythmias in patients with chronic IHD

4 The layout of the thesis

The thesis had 125 pages, including: introduction and study objectives (2

pages), overview (35 pages), research objects and methods (19 pages), research

results (28 pages), discussion (36 pages), conclusion (2 pages) and recommendations (1 page) The thesis had 50 tables, 3 charts, 12 images, 170

references, 17 of which were Vietnamese and 153 English

CHAPTER 1: OVEVIEW

Chronic IHD, also known as chronic CAD, was a condition that occured when blood flow to the heart was reduced, usually dued to a partial or completed blockage of the coronary arteries that feed the heart, reducing the heart's ability

to pump, leading to heart failure, to heart attacks or serious arrhythmias

1.1 Causes

- Atherosclerosis: Atherosclerotic plaque accumulated on the thickened coronary artery wall, narrowing the coronary artery, obstructing blood flow, this was the most common cause

- Blood clots: Atherosclerotic plaques could rupture causing blood clots, blocking the coronary arteries leading to myocardial ischemia Sometimes blood clots traveled from somewhere else

- Coronary artery spasm: Prinzmetal's syndrome

- Other causes: exertion, emotional stress, cold, stimulant abuse, overeating, violent sex

1.2 Symptoms

1.2.1 Symptoms

- Angina: the most important clinical symptom The pain was usually behind the sternum and was an area (not a point), could spread to the neck, shoulder, hand, jaw, epigastric, back, commonly opened out to the left shoulder, then spread to the inner surface of the left hand, sometimes down to the fingers

4, 5 It occured while exertion, strong emotions, cold, after a lot of meals or smoking and quickly decreased/ disappeared within a few minutes when the above factors decreased

- Dyspnea: In patients with high risk of CAD, dyspnea was an important clinical indicator and was recommended by the ESC 2019 in addition to angina

of ischemic arrhythmias

- Assess the prior probability and the likelihood of disease

- Select the appropriate diagnostic exploration method

1.5 Complications of chronic IHD

- Myocardial infarction (MI): A coronary artery was completely blocked

leading to MI, which was one of the serious complications, which could be fatal

- Heart failure: Over time, IHD could lead to heart failure

- Arrhythmias: Abnormal heart rhythms could disrupt the heart's

contractile activity, which could be life-threatening Includes: tachyarrhythmias (ventricular tachycardia, ventricular fibrillation) and bradyarrhythmias (sick sinus syndrome )

 Mechanism of arrhythmia in patients with chronic IHD

Ischemia caused electrophysiological changes in myocardial cells, dispersed the repolarization and refraction time between the ischemic and healthy myocardium, changed electricity in ischemic hypertrophic myocardium, as well as after repolarization refraction, decreased conduction velocity At the same time there was an extracellular accumulation of potassium, the action of the sodium - potassium pump was incompletely inhibited in the ischemic myocardium, reducing the ability to maintain the potassium concentration difference The process of ischemia changed cell membrane permeability, changed the entry and exit mechanism of ions, changed intracellular Ca++, increased extracellular K+, decreased intracellular and extracellular pH, increased Ca++ and Na+ influx Accumulation of lysophospholipids inhibited some ion channels, causing changes in action potentials, causing cardiac arrhythmias In addition,

4myocardial ischemia also increased catecholamine release, adrenorecepter activation leading to an increased risk of ventricular arrhythmias

1.6 Late potential and signal averaged electrocardiogram (SAECG)

Late potential was considered to be the body surface expression of late conduction in the heart, caused by ischemic or damaged myocardial areas, in patients with chronic ischemic heart disease or chronic heart failure In many studies, it had been found that there was a high rate of coronary artery disease in patients with dangerous ventricular arrhythmias Therefore, late potential was a prognostic indicator of patients at high risk of developing dangerous ventricular arrhythmias such as ventricular tachycardia, ventricular fibrillation in patients with chronic ischemic heart disease

Ventricular late potentials are high-frequency, low-amplitude waves (1 to

40 µV), occurring in the terminal part of the QRS complex, recorded by a signal averaging and amplifying electrocardiogram (SAECG) Late potential parameters include:

+ HFQRS: The QRS duration based on the filtered high frequency signal

+ LAHF: Duration of the high frequency, low amplitude portion at the end

CHAPTER 2: RESEARCH OBJECTS AND METHODS

2.1 Objects

 Selection criterias

Selection criterias for patients

162 old MI patients with or without revascularization, or patients had coronary angiography with stenosis greater than 50% of the diameter of the coronary artery

Selection criterias for control group

87 people with no history and/or no cardiovascular disease or conditions affecting the heart: physical examination, 12-lead ECG at rest, routine echocardiography showed normal results

 Exclusion criterias

Who need of immediate treatment: acute coronary syndrome, persistent ventricular tachycardia, ventricular fibrillation, high-grade atrioventricular block, severe electrolyte disturbances… Who was taking drugs that affect the heart rhythm a lot, such as: Digoxin, Atropin, Amidarone but could not be stopped Who had results

of SAECG and Holter were too noisy, the time of wearing the Holter electrocardiogram machine was less than 22 hours Not agreeing to participate in the study

2.2 Methods

Methods: Cross-sectional, descriptive, controlled study Objects were

asked about the disease, taking history and risk factors for CAD

Time: from 3/2016 to 10/2018

Place: 108 Military Central Hospital

Research steps

- Step 1: Made a medical record (Appendix I)

- Step 2: Explained and requested to patients to participate in the study Collected information on history, examined for symptoms

- Step 3: Laboratory tests: blood test, electrocardiogram, echocardiogram

- Step 4: Recording 24-hour Holter ECG, recording SAECG

- Step 5: Collecting and processing research data

 Signal averaged electrocardiogram recording procedure

- Preparing the SAECG

- Attaching electrodes on the skin:

according to the specified positions

- Measuring late potential parameters

on SAECG:

+ HFQRS: (ms)

+ LAHF: (ms)

+ RMS40: (µV)

+ Noise: Required less than 1µV, if above 1µV would be removed

Diagram of parameters of late potential

5 E (brown): Intercostal space 5, mid5 thoracic (near the nasopharynx)

- A (black): Same level as E in the left midaxillary line

- S (red): The apex (hilt) of the sternum

- I (white): Same level as E and A, right mid-axillary line

- Ground (green): in the middle of the

sternum or any other convenient location

- Attaching the electrode and connecting

the 24-hour Holter recorder

- Setting program for Holter system

- Unplug the device after 24 hours

 Analysing 24 - hour Holter ECG result

Analyzing parameters: mean heart rate, fastest, slowest heart rate, ventricular and supraventricular arrhythmias, number of extrasystoles, features

of ventricular arrhythmias according to Lown's classification

CHAPTER 3: RESULTS OF THE STUDY 3.1 General features of study objects

3.1.1 Features of age, gender

The number of patients with chronic IHD was more common in the 61-75 age group (79.4% women and 64.1% men in this age group) Rarely in women under 60 years of age, and no young women < 45 years with chronic IHD Meanwhile, the number of male patients under 45 years old with chronic IHD accounted for 2.3%

Location of electrodes

Table 3.1 Comparison of age and gender of the study objects

Parameters Patients group

(n = 162)

Control group

Age (year) 66,91 ± 8,92 64,15 ± 7,82 > 0,05* Gender Male 128 (79%) 60 (69%) > 0,05**

(*: t-test, **: χ2 -test)

3.2 Clinical, subclinical and late potential features in study objects

3.2.1 Clinical features

 Heart rate, blood pressure of study objects

Table 3.3 Heart rate, blood pressure of study objects

Parameters Patients group

(n = 162)

Control group

Heart rate (bpm) 78,25 ± 8,66 76,47 ± 7,14 > 0,05 Systolic BP (mmHg) 125,74 ± 10,91 119,60 ± 6,30 < 0,05

Table 3.4 Features of heart failure of chronic IHD patients

80

09 00

 Other symptoms

Table 3.5 Other clinical manifestations in patients with chronic IHD

Percentages in total of patient (n=162)

3.2.2.5 Features of 24-hour Holter ECG results

Table 3.13 24-hour Holter ECG results in 2 groups

Parameters Patient group

Control group (n = 87)

arrhythmias/

complicated VPCs

Grade 3 4 (2,5%) 0 (0%)

- Grade 4 (a, b) 42 (25,9%) 0 (0%)

Grade 5 9 (5,6%) 0 (0%)

(χ2- test)

3.2.3 Ventricular late potential features

3.2.3.1 Ventricular late potential features of chronic IHD and control group

Table 3.15 Results of late potential parameters

Parameters Patient group

(t – test)

Table 3.16 Late potential classification in patient and control groups

Classification Patient group

3.2.3.2 Late potential features in patients with chronic IHD

Table 3.17a Parameters of abnormal late potential and normal late potential

Các thông

số

Nhóm ĐTM bất thường (n = 62)

Nhóm ĐTM bình thường (n = 100) p

HFQRS (ms) 111,71 ± 17,39 82,30 ± 11,51 < 0,001

LAHF (ms) 41,11 ± 6,54 28,87 ± 9,39 < 0,001

RMS40 (µV) 16,84 ± 3,91 29,86 ± 12,75 < 0,001

(t – test)

 The incidence of abnormal LP in different age groups

Table 3.18 Compared incidence of abnormal LP in age groups

Age groups Normal LP

 Late potential features related with gender

Table 3.19 Compared incidence of abnormal LP in 2 subgroups

 Late potential features in chronic IHD patients with smoking

Table 3.22 Late potential features related with smoking

 Late potential features in chronic IHD patients with alcohol abuse

Table 3.23 Late potential features related with alcohol abuse

Parameters Alcohol abuse

 Late potential features in chronic IHD patients with reduced EF

Table 3.28 LP features in group with EF < 40% and group with EF ≥ 40%

3.3.1 The relationship between late potential with some clinical features

3.3.1.2 Risk of abnormal LP associated with some clinical features and risk factors in patients with chronic IHD

Table 3.30 Risk of abnormal LP associated with clinical features

Clinical features

Normal LP (n=100)

3.3.2 The relationship between late potential with some subclinical features

3.3.2.1 The relationship between late potential with ECG features

Tabel 3.32 The relationship between ischemic location on ECG and late

Front wall

Back wall

Lateral wall

Multi region

Normal

(n, %)

67 (72,8%)

7 (41,2%)

9 (56,3%)

6 (60%)

11 (40,7%) Abnormal

(n, %)

25 (27,2%)

10 (58,8%)

7 (43,7%)

4 (40%)

16 (59,3%)

Abnormal LP (n = 62) OR 95%

3.3.2.4 Risk of abnormal LP associated with wall dyskinesia

Table 3.35 Risk of abnormal LP in patients with wall dyskinesia

Features

Normal LP (n = 100)

Abnormal LP (n = 62) OR 95%CI p

3.3.3 Relationship between late potential and ventricular arrhythmias (VA) in patients with chronic IHD

3.3.3.2 Evaluation of the risk of VA in patients with abnormal LP

 Risk of couplet ventricular premature complexes (VPCs)

Table 3.37 Risk of couplet VPCs in chronic IHD

Parameters

Without couplet VPCs (n = 108)

With couplet VPCs (n=54)

HFQRS Normal 97 89,8 26 48,1 9,50

4,18-21,58 < 0,001 Abnormal 11 10,2 28 51,9

LAHF Normal 89 82,4 10 18,5 20,61

8,84-48,06 < 0,001 Abnormal 19 17,6 44 81,5

RMS40 Normal 73 67,6 5 30,4 20,44

7,49-55,81 < 0,001 Abnormal 35 32,4 49 69,6

(χ2- test)

 Risk of ventricular tachycardia in chronic IHD

Table 3.38 Risk of ventricular tachycardia in chronic IHD

Parameters

Without ventricular tachycardia (n = 127)

With ventricular tachycardia (n=35)

HFQRS Normal 106 83,5 17 48,6 5,35

2,37-12,03 < 0,001 Abnormal 21 16,5 18 51,4

LAHF Normal 95 74,8 4 11,4 23,01

7,54-70,21 < 0,001 Abnormal 32 15,2 31 88,6

RMS40 Normal 77 60,6 1 2,9 52,36

6,95-394,78 < 0,001 Abnormal 50 39,4 34 97,1

(χ2- test)