P WAVE
DISPERSION AND ITS ASSOCIATION WITH DIASTOLIC DYSFUNCTION IN ASYMPTOMATIC
POPULATION OF THE URBAN AND RURAL MALAYSIA
MOHD FARID BIN MOHD TAUFIK
MSc
2016
Chapter One
INTRODUCTION
1.1
INTRODUCTION
Atrial fibrillation
(AF) enforce consequential concern of morbidity and impaired health related to general
well-being of individuals, and extremely increases sufferer’s risk of obtaining
a cardiovascular event, especially a stroke (apoplexy). Occurrence of atrial
fibrillation in Asia and the associated medical care expenses are likely to
have been underestimated and are required to improve due to increasing
awareness, population ageing and higher prevalence of associated risks and
comorbidities [1].
AF is the most persistent cardiac arrhythmia, and its
occurrence in the population is increasing [2]. AF shares many common
risk factors with left ventricular diastolic dysfunctio (LVDD), including age [3][4][5], hypertension [3][6][4][7], obesity [8], and
diabetes [9][10]. Patients given the
diagnosis of LVDD are more likely to have AF at the time [11]. LVDD has significant
pathological effects on atrial structure and atrial function especially LA,
many are proarrhythmic that can induce arrhythmias such as AF. Nevertheless, there
are so many aspects to be learned about the specific mechanisms through which LVDD
induced development of AF [12].
There is growing understanding that
congestive heart failure (CHF) caused by a significant LVDD that recognised as
diastolic heart failure (HF). Common and causes significant morbidity and
mortality is Diastolic HF [5]. Maintainance of sinus rhythm and normal atrial electrical conductions is
vital for stability of cardiac output in individual with significant LVDD. Occurrence of AF causing atrial output
to decreases. This will results in an increase of LVDD and progression of
diastolic HF the patient’s clinical condition deteriorates [6].
There are many noninvasive
electrocardiographic parameters have been applied to predict the occurrance of cardiac
arrhytmias in individual with LVDD. It has been demonstrates that P wave
dispersion as a noninvasive parameter that
enables the evaluation of AF risk on the 12 lead surface ECG. This is because
of its association to the nonhomogenous and interrupted conduction of sinusal electrical
impulses both intra-atrially and inter-atrially [13][14].
LVDD is an
important risk factor of AF, because LVDD has fundamental pathological influences
on atrial structure and atrial function. Vranka et al. [15] attempted to determine how LVDD increases LAP and LA
diameter, both of which influence atrial conduction times measured noninvasively
by electrocardiography of P wave.
Researcher will investigate the
association between P wave dispersion and the presence of LVDD as detected by
Doppler echocardiography, the stage, origin, and other echocardiographic
indicators of LVDD that includes LA volume, LA volume index, LA dimension, LA active
emptying fraction, LA total emptying fraction and other echocardiography
parameters that can represent performance of LA in individual with asymptomatic
AF, individual with type 2 diabeties melitus (DM), individual with hypertension
and individual that is asymptomatic
healthy individual.
1.2
PROBLEM STATEMENT
P wave dispersion can be used in predicting the risk of AF [13] in LVDD patient. Gunduz et al. [16] in their finding noted that the presence of LVDD
is an important factor affecting P wave duration. The goal of the proposed
study is to investigate association between LVDD, P wave dispersion and AF.
P wave measurement by 12 lead ECG have been stated to be applicable tools
for assessing the risk of LA enlargement and LVDD [16][17]. Gunduz et al. [16] in their finding noted that prolongation in P
wave dispersion is related to LA diameter or to stage of LVDD. Gunduz et al. [16] in their finding also noted as LVDD stage of
patient progressed, LA dimensions increased significantly. However, Dilaveris et
al. [13] have found that LA diameter is not an
important predictor for AF and that P wave duration is unrelated to LA
diameter. The purpose of the proposed study is to determine the effect of LVDD
on LA diameter and its association with P wave dispersion.
Earlier Tsang et al. [18] have done an early study to examine LVDD and
incident AF. They followed 840 elderly men and women, of whom 80 (9.5%)
developed atrial fibrillation over a average follow up of 4.1 years. With the
use of a derived classification system for LVDD based on transmitral Doppler
patterns and LA volume index. They found that more severe LVDD was related with
an elevated risk of AF incident. Tsang et al. [18] in their study of 840 elderly men and women also
suggest that the strongest predictor of AF was LA volume index.
Later Tsang et al. [19] have done follow-up study that
examined only patients with impaired relaxation based on transmitral peak E/A
(0.75) and deceleration time (240ms) and found an increased risk of the
combined outcome of AF and HF with impaired relaxation, although this effect
was not significant in the absence of an increased LA volume index (27 mL/m2).
This finding again suggesting that it was LA size, rather than any particular
diastolic parameter, that increases risk of AF. In addition, normal LA volume
in a patient with advanced LVDD is most unusual unless the LV filling pressure
increase abruptly because of the sudden onset of a structural abnormality, such
as severe mitral regurgitation or aortic regurgitation due to sudden valvular
disruption or valvular abnormalities. LA volume is a good predictor of the
development of AF and long term outcome in various cardiac disorder [19]. The purpose of the
proposed research is to determine the effect of LVDD on LA volume and LA volume
index and its association with P wave dispersion.
Faggiano et al. [20] in their study show the relationship between LAP
or pulmonary capillary wedge pressure (PCWP) obtain by right sided heart catheterization
and obtain by echocardiography to signal averaged P wave duration in patients
with CHF. The
author believes that in patients with chronic HF, P wave duration in signal
average ECG seems to depend more on the level of LAP compare to LA dimension.
Vranka et al. [15] supports Faggiano et al. [20] with their result that high left atrial
pressure expressed by increased E/E’ ratio, may be play an important role in
prolonging P wave duration, as was shown by Doppler parameters. The author
suggest that prolonged atrial conduction was not associated with LA
enlargement. The goal of the proposed study is to examine association between LVDF
and its effect on P wave dispersion and LA.
Morris et al [21] mentions that individuals with HF with normal
LVEF had more impaired LA systolic function compared to asymptomatic
population. The author states that noninvasive LV filling pressure were
modestly related with LA systolic function. The goal of the proposed study is
to investigate association between LVDD and its effect on P wave dispersion and
LA systolic function.
In essential hypertension in adult individuals, a significant relationship
has been showed between changes in LV geometry and P wave dispersion. P wave dispersion is the difference between
maximum and minimum P wave duration measured on 12 lead ECG [13]. Hypertension is one of the causes of AF. LVDD
in a hypertrophic LV results in an increase in LV end diastolic pressure and in
LA dimension [22]. De Marchi et al. [23] showed an important association between the
extent of hypertrophy and LVDD. The target of the proposed study is to examine
the relationship between LVDD, LV hypertrophy, P wave dispersion and its effect
on LA dimension, LA volume and LA
volume index in hypertensive population.
Patil and colleagues [10] in their finding stated that preclinical LVDD
is common in patient with DM. Soldatos et al. [24] in their case control study of individuals
with Type 2 DM found that LVDD, present in a significant proportion with Type 2
DM. Boyer et al. [25] stated that the prevalence of LVDD in
asymptomatic, normotensive patients with Type 2 DM disease is high. Yazici et
al. [26] also manage to show that prolongation of P
wave dispersion can be seen in Type 2 DM cases without hypertension and
ischemic heart disease. They found that slightly prolong P wave dispersion in
the Type 2 DM group compare to the control group but diastolic relaxation
parameters, such as early diastolic rapid filling and isovolumic relaxation
time (IVRT) were within normal value and mean LA diameter were similar in both
groups. Depends on these findings, P wave dispersion is not affected by
these diastolic parameters. The aim of the proposed study is to examine the
relationship between LVDD, LV hypertrophy, P wave dispersion and its effect on LA
dimension, LA volume and LA volume index in diabetic population.
1.3
OBJECTIVES
1.3.1
Main
Objective
To investigate
association between Left Ventricular Diastolic Dysfunction (LVDD), P wave
dispersion and AF.
1.3.2
Objectives
1. To investigate association
between LVDD and its effect on P wave dispersion, LA dimension, LA volume and LA
volume index.
2. To investigate
association between LVDD and its effect on P wave dispersion, LA systolic
function and LAP.
3. To examine the
effect of LVDD on LA dimension, LA volume, LA volume index, LA systolic
function and LAP with presence of increased P wave dispersion compared to
healthy controls.
4. To examine the
effect of LVDD on LA dimension, LA volume, LA volume index, LA systolic
function and LAP with presence of increased P wave dispersion compared to
hypertensive population.
5. To examine the
effect of LVDD on LA dimension, LA volume, LA volume index, LA systolic
function and LAP with presence of increased P wave dispersion compared to
diabetic population.
1.4
RESEARCH QUESTION
Does prolonged P
wave dispersion cause AF?What is the
relationship between P wave dispersion and LVDF?
3.
What is the association
between LVDD and its effect on P wave dispersion, LA dimension, LA volume and LA
volume index?
4.
What is the association
between LVDD and its effect on P wave dispersion, LA systolic function and LAP?
What is the effect
of LVDD on LA dimension, LA volume, LA volume index, LA systolic function and LAP
with presence of increased P wave dispersion compared to healthy controls?
What is the the
effect of LVDD on LA dimension, LA volume, LA volume index, LA systolic
function and LAP with presence of increased P wave dispersion compared to
hypertensive population?
What is the the
effect of LVDD on LA dimension, LA volume, LA volume index, LA systolic
function and LAP with presence of increased P wave dispersion compared to
diabetic population?
1.5
RESEARCH HYPOTHESIS
1.
Normal P
wave duration, LVDD, LA dimensions, LA area, LA volume, LA volume index, LA
active emptying fraction and LA total emptying fraction in control group.
2.
Prolong P
wave duration and dispersion in study
group with hypertension.
3.
Prolong P
wave duration and dispersion study
group with type 2 diabetes mellitus.
4.
Prolong P
wave duration and dispersion with
evidence of LV hypertrophy in study group with hypertension and diabetes
mellitus.
5.
The LVDD
worsens in study group with
hypertension.
6.
The LVDD
worsens in study group with type 2 diabetes
mellitus.
7.
LA
dimensions, LA area, LA volume, LA volume index and LAP were significantly
increased in study group with
hypertension.
8.
LA
dimensions, LA area, LA volume, LA volume index and LAP were significantly
increased in study group with type 2
diabetes mellitus.
9.
LA active
emptying fraction and LA total emptying fraction were significantly reduced in study group with hypertension.
10. LA active emptying fraction and LA total
emptying fraction were significantly reduced in study group with type 2 diabetes mellitus.
1.6
SIGNIFICANCE OF THE STUDY
AF is the most common persistent cardiac arrhythmia, and increasing in prevalence.
AF occurs in 0.3% to 0.4% of the adult group [9]. The impact of AF on morbidity and mortality is high.
It will give socioeconomic burdened to the society. AF is most commonly seen in
patients with underlying structural heart disease, including hypertensive population,
cardiomyopathy, ischemic heart disease, valvular heart abnormalities and HF [27].
Early identification of patients at risk of AF may help to reduce
potential health risks, costs and other related complications. P wave
dispersion analysis has been shown to classified between individuals at risk of
AF and those without risk of AF. P wave prolongation on may be associated with left
ventricular diastolic dysfunction and following an increase of LAP, LA
enlargement and reduced LA systolic function; therefore, P wave prolongation should be assessed in individuals
at risk of AF. Combining P wave duration with other predictors of AF may
improve the diagnostic value of P wave dispersion analysis [15].
In condition of ncreased in LV end diastolic pressure with LVDD, the
maintainance of normal sinus rhythm and atrial contractions is essential for
the maintainance of cardiac output. If AF occurs, the loss of efficient atrial contraction,
which accounts for 40% of atrial output during diastolic phase. This will
results in worsening of LVDD and in progression of diastolic HF [6].
Identifying association of P wave dispersion with early echocardiographic
changes especially on LVDF assessment allow physicians to intervene and manage
underlying illnesses more aggressively to reduce risk of development of AF.
Potential health risk such as hypertension and Type 2 DM nowadays have
increasing in Malaysia population has been proved to be risks factors of LVDD
and P wave dispersion. Early treatment of this potential risk can also reduced risk
of developing AF.
1.7
DELIMITATIONS OF THE STUDY
The study will be limited to an investigation of respective knowledge
specifically on non invasive LVDD evaluation by 2D echocardiography and Doppler
echocardiography modalities analysis. The study also will be limited to an
investigation of respective knowledge on non invasive 12 lead surface ECG
analysis specifically on P wave characterictic. Invasive LVDD and intra cardiac
electrophysiology study evaluation will not be obtain and tested.
1.8
LIMITATIONS OF THE STUDY
The LA function will only focusing on systolic
function. Left atrial diastolic function evaluation has to be done by strain
imaging. Strain imaging did not included in raw database to be obtain, test and
evaluate.
