Correlation between left atrial electromechanical delay and degree of left ventricular diastolic dysfunction in patient with sinus rhythm and preserved systolic function

Ossama Maadarani*, Hany Alfayed¹, Zouheir Bitar², Rashed Alhamdan³, Mohammad Alrashidi⁴

1,2,3,4. Internal Medicine Division, Cardiology Unit, Ahmadi Hospital, Kuwait Oil Company, Ahmadi, Kuwait.

Corresponding Author: Ossama Maadarani, Internal Medicine Division, Cardiology Unit, Ahmadi Hospital, Kuwait Oil Company, Ahmadi, Kuwait.

Copy Right: © 2022 Ossama Maadarani. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received Date: December 27, 2021

Published Date: January 01, 2022

Abstract

Background: The Atrial electromechanical delay (AEMD) is defined as the delay between the onset of electrical activity and the initiation of atrial contraction and measured using Tissue Doppler imaging (TDI) and electrocardiogram(ECG). Diastolic dysfunction of the left ventricle (LV) is defined as a condition caused by increased resistance to the filling of LV which may cause symptoms of heart failure. Determining the degree of LV diastolic dysfunction is an important step in echocardiographic laboratory and required the assessment of several parameters according to guidelines of the American Society of Echocardiography (ASE) and the European Association of Cardiovascular Imaging (EACVI) in 2016.
 

Aim: To investigate the relationship between left atrial electromechanical delay, measured using ECG and TDI and the presence, degree of left ventricular diastolic dysfunction in patients with sinus rhythm and preserved systolic function

Methods: This paper reports a prospective observational study of 30 patients who underwent two-dimensional (2D) transthoracic echocardiography (TTE) to assess the degree of LV diastolic dysfunction and to measure left atrial electromechanical delay in a patient with sinus rhythm and preserved systolic function. AEMD was defined as the time-interval between P-wave on ECG and the beginning of the averaged spectral TDI-derived A’ (septal and lateral sides of the mitral annulus)

Result: 30 participants were included in the study. 6 patients had normal diastolic function (Group 1), 8 patients had diastolic dysfunction grade I (group 2), 11 patients had diastolic dysfunction grade II (group 3) and 5 patients had grade III diastolic dysfunction (group 4). The mean value of AEMD for group 1 was 41 milliseconds whereas the mean AEMD for groups 2, 3 and 4 were 53, 74.8 and 98.6 milliseconds respectively.

Conclusion: Worsening of LV diastolic dysfunction is probably associated with prominent prolongation of atrial electromechanical delay. AEMD may predict the degree of diastolic dysfunction.

Keywords: left ventricular Diastolic dysfunction, atrial electromechanical delay, Tissue Doppler imaging.

Background

Assessment of LV diastolic dysfunction in a patient presenting with symptoms of dyspnea or heart failure is an important part of the echocardiographic study. In 2016 An Update from the American Society of Echocardiography (ASE) and the European Association of Cardiovascular Imaging (EACVI) recommended Several two-dimensional (2D) and Doppler parameters to grade diastolic dysfunction (1). Despite the presence of these several parameters in the flow chart grading diastolic dysfunction, still few patients had labeled as unable to determine the grade of their diastolic dysfunction. Introducing a parameter like left atrial electromechanical delay may help to assess LV diastolic dysfunction in patients with sinus rhythm and preserved systolic function.

Methods

Study Design:

This study is a prospective, observational study that includes an adult patient who was referred to an echocardiography laboratory to undergo a transthoracic echocardiographic study for clinical indication within a 2-month period that ended in august 2021. The study was performed at echocardiography laboratory in Ahmadi hospital, a subsidiary of Kuwait Oil Company. The 30 patients enrolled were of various age groups and both sexes. Most of the patients used for this study had one or more of the following problems: diabetes mellitus, Hypertension, stable coronary artery disease.

The inclusion criteria were patients above 18 years with normal LV systolic function and a sinus rhythm on electrocardiogram. Exclusion criteria were patients with LV ejection function of less than 50%, chronic atrial fibrillation, severe mitral annulus calcification on Echocardiographic study, patients with the pericardial disease, restrictive and constrictive cardiomyopathy.

Protocol

All the patients underwent a full 2-dimensional transthoracic echocardiographic examination using a transducer 5 MHZ Philips iE33 device. No contrast material was used. The echocardiography scan was performed by a well-trained echocardiographer. The echocardiographic images were saved to a hard drive and reviewed in the system by the expert echocardiographer who supervises the echocardiography laboratory. The echocardiographic examination is consistent with obtaining standard views of the parasternal long axis as well as apical 4-and 5-chamber views. A full echocardiographic examination including two-dimensional (2D) and spectral Doppler study in addition to Tissue Doppler imaging (TDI) as per current American Society of Echocardiography (ASE) guidelines.

Left AEMD was measured from the beginning of the electrocardiogram P-wave to the initial point of the spectral TDI-derived A’ (2) (Figure 1). In this study, left AEMD was obtained for the septal (septal EMD) and lateral (lateral EMD) sides of the mitral annulus. Averaged AEMD was calculated for each patient.

To assess LV diastolic dysfunction the following parameters were measured according to the 2016 update of ASC and EACVI recommendation:

1-Mitral flow velocities using pulsed Doppler including early rapid filling ( E wave ) and late filling with atrial contraction (A wave )  and their ratio (E/A) from apical 4- chamber view. ( Figure 2)

2- Mitral annular early (E’) and late (A’) filling velocities using tissue Doppler imaging from apical 4-chamber view and pulsed Doppler.

3- E/E’ ratio

4- Peak velocity of Tricuspid Regurgitation (TR) jet from apical 4- chamber view using color Doppler flow

5- Left atrium volume indexed from apical 2, 4-chamber views.

Patients were categorized according to the grade of diastolic dysfunction into 4 groups. Group 1 when the diastolic function is normal, group 2 –patient with grade I diastolic dysfunction, group 3 –patients with grade II diastolic dysfunction and group 4 patients with grade III diastolic dysfunction.
 

Results

30 participants were included in the study. 14 patients were male and the rest of the patients were female. The average age was 62 years. 25 patients had diabetes mellitus, 15 patients had stable coronary artery disease and hypertension. 6 patients had normal diastolic function (Group 1), 8 patients had diastolic dysfunction grade I (group 2), 11 patients had diastolic dysfunction grade II (group 3) and 5 patients had grade III diastolic dysfunction (group 4). The mean value of AEMD for group 1 was 41 milliseconds whereas the mean AEMD for groups 2, 3 and 4 were 53, 74.8 and 98.6 milliseconds respectively. We found a tendency of more prominent prolongation of AEMD whenever the diastolic dysfunction grade increased (figure 3). Worsening in diastolic dysfunction may be associated with prolongation of left AEMD.
 

Discussion

Atrial electromechanical delay demonstrates atrial conduction abnormalities between the surface electrocardiographic and tissue Doppler echocardiographic measurements. AEMD is measured from the beginning of the electrocardiogram P-wave to the initial point of the spectral TDI-derived A’ wave (2). In general electromechanical delay has been defined as the temporal interval between the onset of cardiac electrical activity and myocardial contraction (3). Demir et al reported in one study a significant prolongation of AEMD in patients with Type 2 diabetes mellitus as compared with healthy volunteers (4).  Atrial conduction abnormalities can happen in elderly patients who suffered from diseases like hypertension and diabetes mellitus in addition to metabolic syndromes (5). The majority of these patients had a degree of diastolic dysfunction on echocardiographic examination. It was reported in many studies that prolongation of left AEMD was a predictor of new-onset Atrial Fibrillation (AF) and recurrence of AF (6). The exact mechanism of prolongation of left AEMD in patients suffering from Diabetes mellitus type 2 and hypertension is not well known, but it is thought that structural and electrophysiological changes in the atrial myocardium caused by might play a role. Diastolic dysfunction was reported up to 75% in diabetic and hypertensive patients (7). In one study the duration of left atrial EMD was prolonged in patients with preeclampsia which is characterized by new-onset hypertension and proteinuria (8).

The structural and electrical changes that happened in the left atrium inpatient with diastolic dysfunction due to variable conditions might explain the prolongation of left atrial electromechanical delay (8) and based on this assumption our hypothesis suggests that with worsening of diastolic dysfunction we may observe more prolongation of left atrial EMD. In another word, the measurement of left AEMD may help determine the presence of diastolic dysfunction and possibly the grade when other parameters are undetermined. To our knowledge, no study assessed left atrial conduction abnormalities using both TDI and ECG in patients with diastolic dysfunction. In our study, the prolongation of left atrial EMD was more prominent in a patient with advanced diastolic dysfunction.

Conclusion:

Worsening of LV diastolic dysfunction is probably associated with prominent prolongation of left atrial electromechanical delay. AEMD may predict the degree of diastolic dysfunction. 
 

Limitation:

The small number of patients recruited is one of the major limitations but the study can be considered as a pilot one.

References

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