4. Luan An Tom Tat (Eng).Pdf

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF DEFENCE 108 INSTITUTE OF CLINICAL MEDICAL AND PHARMACEUTICAL SCIENCES VIEN HOANG LONG CLINICAL, PARACLINICAL CHARACTERISTIC, ELECTROPHYSIOLOGICAL FEATURE[.]

OF EDUCATION AND TRAINING OF DEFENCE

108 INSTITUTE OF CLINICAL MEDICAL AND

PHARMACEUTICAL SCIENCES

VIEN HOANG LONG

CLINICAL, PARACLINICAL CHARACTERISTIC, ELECTROPHYSIOLOGICAL FEATURES AND RESULT OF PERSISTENT ATRIAL FIBRILLATION ABLATION WITH

INSTITUTE OF CLINICAL MEDICAL AND

PHARMACEUTICAL SCIENCES

Supervisor 1: Assoc.Prof.PhD: Pham Quoc Khanh

2: Assoc.Prof.PhD: Pham Nguyen Son

- National Medical Informatics Library

- Library of 108 institute of clinical medical and pharmaceutical sciences

1 Long V H., Khanh P Q., & Son P N (2023) Clinical

characteristics and electrophysiological features in patients with persistent atrial fibrillation undergoing radiofrequency

energy ablation Journal of 108 - Clinical Medicine and Pharmacy, 17(TA) https://doi.org/10.52389/ydls.v17iTA.1639

2 Long V H., Khanh P Q., & Son P N (2023) The results of

persistent atrial fibrillation ablation with radiofrequency

energy after a six-month follow-up Journal of 108 - Clinical Medicine and Pharmacy, 17(TA) https://doi.org/10.52389/

ydls v17iTA.1636

INTRODUCTION

1 Urgency of research

Over the past 20 years, atrial fibrillation (AF) has become one

of the most investigated arrhythmias and has incurred significant healthcare costs in developed countries Besides causing symptoms and affecting quality of life, AF is a leading cause of systemic thromboembolism, stroke, heart failure, mortality, and increased hospital readmission rate in patients with cardiovascular disease According to the European Society of Cardiology statistics in 2016, there are approximately 43.6 million AF patients worldwide, and the incidence of AF increases with age and coexisting cardiovascular risk factors Unlike other arrhythmias, AF tends to progress from paroxysmal AF to persistent and eventually long-standing persistent

AF over time Early rhythm control intervention for paroxysmal and persistent AF would reduce the progression to long-standing persistent AF Until now, there have been many advances in the management of AF with promising results In 1994, Haissenguerre

M first applied radiofrequency energy to treat AF patients, but the success rate was low (33-60%), the complication rate was high, and the procedure took up to 5-6 hours From 1996, Pappone C used the three-dimensional CARTO cardiac mapping system to treat AF with radiofrequency energy Despite many advances and improvements in tools, techniques, and success rates in maintaining sinus rhythm after intervention for patients with persistent AF, the success rate is not as high as those with paroxysmal AF In addition, the cost of an ablation procedure for AF (especially in Vietnam) is also high Therefore, ablation intervention for persistent AF has not been widely performed and researched in Vietnam

3 The scientific and practical significance of the research

- Identifying associated atrial arrhythmias and accompanying substrate abnormalities in persistent atrial fibrillation patients, assessing cardiac electrophysiological characteristics after sinus rhythm restoration

- Determining the success rate of maintaining sinus rhythm and changes in clinical symptoms of patients in the 6-month following-up persistent atrial fibrillation ablation using radiofrequency energy

- Evaluating the correlation between early recurrence of atrial fibrillation (≤ 3 months post-intervention), time from atrial fibrillation diagnosis to intervention, and the success rate of maintaining sinus rhythm after 6 months This helps in selecting and predicting patients with a higher success rate for the treatment method

4 The structure of the dissertation

- The thesis consists of 87 pages (excluding references and appendices), structured into 7 sections: Introduction (2 pages), Literature overview (9 pages), Subjects and Methods (18 pages), Results (30 pages), Discussions (25 pages), Conclusions (2 pages), Recommendations (1 page), and List of published papers of the dissertation (1 page)

- Number of tables and figures: 39 tables, 16 figures, 17 pictures

- The references of the dissertation include 108 sources, comprising 9 Vietnamese references and 99 English references

CHAPTER 1: LITERATURE OVERVIEW

1.1 Diagnosis of atrial fibrillation

1.1.1 Definition of atrial fibrillation: A supraventricular

tachyarrhythmia with uncoordinated atrial electrical activation and consequently ineffective atrial contraction

1.1.2 Diagnostic criteria for atrial fibrillation

The diagnosis of AF is based on an ECG tracing heart rhythm with no discernible repeating P waves and irregular R-R intervals ECG tracing of ≥ 30 seconds is diagnostic of clinical AF

- Long-standing persistent AF: Continuous AF of >12 months’ duration when decided to adopt a rhythm control strategy

- Permanent AF: AF that is accepted by the patient and physician, and no further attempts to restore/maintain sinus rhythm will be undertaken

1.2 Atrial fibrillation management

1.2.1 ACB pathway:

According to ESC AF guideline 2020, the simple Atrial fibrillation Better Care (ABC) was recommended for AF management

A: Anticoagulation/Avoid Stroke

B: Better symptom control (choose rhythm control or rate control strategy)

C: Cardiovascular risk factors and concomitant diseases control

1.2.2 Indications for atrial fibrillation catheter ablation

According to 2017 HRS/EHRA/ECAS/APHRS/SOLAECE guideline: Indications for symptomatic paroxysmal AF was Class I-

A, persistent AF was IIa-B In ESC 2020 guidelines recommend persistent AF ablation in symptomatic patients with low risk of recurrence and failure of medical therapy as a class I recommendation

1.3 Recent studies about atrial fibrillation catheter ablation

1.3.1 Overview of study about atrial fibrillation in Vietnam

Currently, in Vietnam, the majority of research on AF is conducted on patients with other comorbidities Only one study by Pham Tran Linh has evaluated the effectiveness of ablative intervention in paroxysmal AF patients There has been no research conducted on ablative intervention in persistent AF patients

1.3.2 Overview of studies about persistent atrial fibrillation

ablation

AF ablation intervention is also one of the outstanding issues

of concern in the world Author groups have proposed new ablation strategies to improve success rates for the AF patient group, especially for persistent AF (Verma A., He X., Kottkamp H Stavakis S )

CHAPTER 2: OBJECTS AND METHODS

2.1 Study objects

Our study included 40 persistent atrial fibrillation patients, all

of these patients were hospitalized and underwent catheter ablation of atrial fibrillation at Vietnam National Heart Institute - Bach Mai Hospital from October 2017 to November 2021

2.1.1 Inclusion criteria

According to 2016 atrial fibrillation guidelines of the European Society of Cardiology (ESC) and the Vietnam Society of Cardiology / Vietnamese Society of Cardiology Electrophysiology (IIa recommendation with level of evidence C), patients who meet the following conditions are indicated for catheter ablation:

- Patients with clinical symptoms who are unresponsive or intolerant to at least one antiarrhythmic drug in group I or III

- Patients with clinical symptoms despite the use of antiarrhythmic drugs in group I or III and who desire a rhythm control strategy

2.1.2 Exclusion criteria

- Paroxysmal AF, permanent AF, age < 18 years old, elderly patients (age ≥ 80 years), thrombus in the heart chamber, heart failure with reduced ejection fraction (EF ≤ 49%), recent stroke, Acute infection and blood clotting disorder

2.1.3 Diagnostic criteria used in the study

Arterial hypertension: is defined according to 2018 ESC guidelines Diabetes is defined according to American Diabetes Association

2017 Excessive alcohol is defined according to U.S CDC guidance

2.2 Methods

2.2.1 Design and sample size

A prospective intervention study with a 6-month follow-up using a convenient sample size

2.2.2 Data collection

2.2.2.1 Clinical examination and investigations

All the patients were examined, recorded 12 – lead ECG Other investigations were done before procedures such as blood tests, chest X-ray, transthoracic echocardiography, trans esophagus echocardiography, multi-sliced CT scanner of left atrium and pulmonary veins

2.2.2.2 Catheter ablation and electrophysiology study

- Place of procedures: Catheterization Laboratory, Vietnam Heart Institute, Bach Mai Hospital

-Equipment: angiography system, stimulator, electrophysiological recording system, ablation generator, three-dimensional mapping system (ENSITE system) and varieties of diagnostic catheters and ablation catheters

+ Criteria of success: confirmed both directional blocked after ablation

2.2.2.3 Follow-up after radio frequency catheter ablation

+ All the patients underwent 24-hour Holter ECG, transthoracic cardiac echo within 24 hours after catheter ablation + Patients were received antiarrhythmic 3 months after procedures

+ Follow-up was carried out with 24 – hour ECG, cardiac echo, blood test after 1 month, 3 months, 6 months

Chart 2.1 Study's protocol

2.3 Statistical analysis

The t-test was used to compare two mean values, and the

chi-square test (2) was used to compare two percentages p-value<0.05 was considered statistically significant Statistical analysis was facilitated by software package SPSS 20.0 and STATA 17.0

2.4 Study ethics

Patients were required to sign an informed consent form acknowledging their understanding of these risks The AF ablation was performed as in “Guidance for cardiovascular technique procedures” issued by the Ministry of Health in 2014

CHAPTER 3: RESULTS 3.1 General characteristics of the study group

From October 2017 to November 2021, we collected 40 symptomatic persistent AF patients underwent catheter ablation with 3D mapping system at Vietnam National Heart Institute - Bach Mai Hospital We obtained the following results

3.1.1 Baseline characteristics

The average age in the study group was 54.25 ± 12.54 years, with 80% of the patients being male The average BMI (Body Mass Index) was 23.63 ± 3.09 (kg/m2)

3.1.2 Age and sex distribution: In our study, the age group ≥ 60

years old accounted for the highest rate of 40%, the age group < 50 and the age group 50 - 59 had the same rate of 30% 80% of patients

in the study were male, 20% of patients were female

3.2 Clinical and paraclinical characteristics

3.2.1 Clinical characteristics

3.2.1.1 Risk factors and cardiovascular diseases history: the most

common risk factor and history of cardiovascular disease in our study group were hypertension (42.5%) and excess alcohol use (37.5%)

3.2.1.2 Clinical symptoms: The most common symptoms in our

study were palpitations (65%) and chest pain (27.5%).100% of patients have symptoms of AF, 67.5% of patients have symptoms at level IIb, 32.5% of patients have symptoms at level III (according to modified EHRA score)

prior to the intervention, with an additional 25% using beta-blockers for rate control The average CHA2DS2-VASc score was 0.9 ± 0.778, and the average HAS-BLED score was 0.65 ± 0.622

3.2.2 Paraclinical characteristics

3.2.2.1 Blood test: All patients in the study were routinely tested

before the intervention of AF treatment with radiofrequency energy The blood test results were within normal limits

3.2.2.2 2D Transthoracic cardiac echo: The proportion of left atrial

dilatation in our study was 35% (cut-off: LA diameter ≥ 40 mm on 2D transthoracic cardiac echo)

3.2.3 Electrophysiological features of persistent atrial fibrillation patients

3.2.3.1 Electrical connection between the pulmonary veins and the left atrium: Four patients had no electrical connection between the

RIPV and the left atrium One patient was unable to convert to sinus rhythm after ablation despite undergoing cardioversion multiple times This patient was considered PVI unsuccessful 39/40 patients got completed PVI

3.2.3.2 Some other atrial arrhythmias and substrates besides AF

In our study, there were 12 cases (accounting for 30%) had specific arrhythmias and substrates involved in the formation of AF, including:

- Low voltage zone (LVZ) (4 cases): Scar zone at anterior and posterior of mitral valve (1 case) (Voltage <0.2 mV), LVZ at anterior wall of LA (1 case), LVZ at anterior wall near roof of RSPV (1 case), scar zone at anterior wall of right PVs (1 case) (Voltage <0.2 mV)

- Atrial flutter (AFL) (5 cases): Roof based atypical AFL + typical AFL (1 case), roof based atypical AFL (2 cases), mitral isthmus based atypical AFL (1 cases), typical AFL (1 case)

- Ganglionated plexi (1 case): Posterior of RIPV

- Non-PVs foci (1 case): Posterior inferior of LIPV

- Rotor (1 case): Anterior lateral of RIPV

3.2.3.3 Electrophysiological features after sinus rhythm recovered

Table 3.11 Basic intervals after sinus rhythm recovered

177.7

34.97  14.44

101.86  32.43

57.89  9.36

85.44  17.47

381.23  43.26 SNRT with stimulation cycles of 500 ms (1235.0  325.62 ms), 400 ms (1291.89  276.63 ms), 330 ms (1445.11  547.33) and SNRTc (667.03  517.21), respectively, tended to be longer than normal subjects The longest SNRT in our study were recorded with atrial stimulation cycle length 300 ms

Table 3.14 Effective refractory period of atrial, ventricular, atrial -

of AVN (ms)

Anterogr ade Wenckeb ach type

AV block occurred (ms)

Retrogra

de ERP

of AVN (ms)

Retrogra

de Wenckeb ach type

AV block occurred (ms)

428.39  75.72 (n=36)

375.0  96.69 (n=9)

443.33  79.84 (n=9)

3.3 Results of catheter ablation for persistent atrial fibrillation

3.3.1 Technique index in catheter ablation for persistent atrial fibrillation

Number

of lesions (points)

Ablation time (minutes)

Number of cardiovers -ion (time)

119.9  38.55

60.42  20.59

1.43  1.13 PVI and

171.4  74.43

75.14  33.29 0.4  0.52

Overall 256.25 

48.61

29.55  14.29

132.77  53.79

64.10  24.76 1.17  1.1 Patients in group PVI and plus strategy had more ablation lesions (p = 0.007) and less time of cardioversions (p=0.009)

3.3.2 The proportion of maintaining sinus rhythm and clinical and paraclinical changes after intervention

3.3.2.1 The proportion of maintaining sinus rhythm

The proportion of maintaining sinus rhythm based on 24h Holter ECG was highest at 3-month follow-up (68.2%), at 6-month follow-up was 60.7%

Figure 3.9: Rate of maintaining sinus rhythm after catheter

ablation for persistent atrial fibrillation

The proportion of maintaining sinus rhythm in the group of isolated pulmonary vein with additional lesions tended to be higher than the group of patients with isolated pulmonary vein alone

3.3.2.2 Changes in clinical symptoms

Figure 3.11 Comparing clinical symptoms between

AF recurrence and AF freedom