Abstract:
Objectives: To assess the correlation between left
atrial (LA) longitudinal strain and occurrence of atrial fibrillation
(AF) in patients with dilated cardiomyopathy (DCM).
Methods: 100 patients with DCM
were evaluated. Conventional and
speckle tracking echocardiography were done to evaluate LA diameters,
volumes and longitudinal strain.
Results: Left atrial dimensions and volumes were
significantly greater in AF group. LA longitudinal strain and LA
emptying fraction were significantly lower in AF group. LA longitudinal
strain and LA minimal volume are independent predictors for AF presence.
ROC curve showed that LA longitudinal strain cut-off value
<11.1% can predict the presence of AF in DCM patients with
96% sensitivity and 95.3% specificity (AUC 0.982, 95% CI 0.959–1.0,
P < 0.001)
Conclusion: Left atrial longitudinal strain was
significantly reduced in AF in the setting of DCM. LA longitudinal
strain and LAVmin are independent predictors for AF occurrence in this
group of patients with LA strain values <11.1% can be used to
predict AF in DCM.
Keywords: Left atrial longitudinal strain, dilated
cardiomyopathy, atrial fibrillation.
Introduction:
Atrial fibrillation (AF) and dilated cardiomyopathy (DCM) are very
closely linked. AF is the most common sustained arrhythmia in patients
with DCM. Patients with DCM have higher probability to develop AF than
those without heart failure [1] .
There is a rising concern about understanding left atrial structure and
function in patients with DCM and AF; due to their different clinical
implications in heart failure as deterioration of LA function during AF
diminishes LV stroke volume that may result in developing of HF
symptoms. In turn, the result of abnormal LV function is increased
filling pressure, negatively affecting LA volume and function[2]. Deterioration of LA function in patients with AF and
DCM is associated with greater risk for cardiovascular events especially
thromboembolic events, hence assessment of LA structure and function is
important to predict both risk for these events and the success of
preventing them [3].
Assessment of left atrial function in patients with DCM and AF with
speckle tracking echocardiography (STE) can explain its role in the
pathogenesis, diagnosis, prognosis and management of this group of
patients [4]. Thus, we aimed at evaluating the correlation
between left atrial strain assessed by speckle tracking echocardiography
and the occurrence of AF in patients with DCM.
Patients and methods:
Study design:
This is a single center cross sectional study that included 100
consecutive patients with DCM refered for echocardiographic evaluation
at cardiology depatment of Benha University Hospitals, Egypt during the
period from January to December 2019. DCM was defined as enlargement and
dilation of the left ventricle with impaired systolic function defined
as left ventricular ejection fraction (LVEF) less than 40%. They were
classified into two groups: group I, 50 patients with DCM and sinus
rhythm and group II, 50 patients with DCM and AF. All the patients of
group I didn’t report any previous episode of AF. ECG was performed for
all patients to confirm the rhythm. The study was approved by the local
ethics committee at our institution, with informed consent from all
patients. Exclusion criteria included organic valvular disease,
prosthetic valves, intra-cardiac shunts, implanted medical devices,
atrioventricular conduction disturbances, rhythm other than SR or AF.
Echocardiography:
Echocardiography was performed with the commercially available system
(Philips EPIQ 7 Ultrasound System, Andover, MA, USA) equipped with
3.5-MHz phased array transducer. LVEF was calculated using the modified
biplane Simpson’s method [5] . LA antero-posterior diameter
was measured in the parasternal long axis view. Transverse and
longitudinal LA diameters were measured in apical four- chamber view[6]. LA volumes were measured at end systole (LA maximal
volume ”LAVmax”) and end diastole (LA minimal volume ”LAVmin”), in
apical four-chamber view. LA emptying fraction (LAEF) was calculated
using the following formula, LAEF = (LAVmax – LAVmin)/LAVmax ×100%[7] . For two-dimensional speckle tracking echocardiography
(2DSTE), sector depth and size were optimized to achieve perfect
visualization of LA in the apical 4-chamber view with a frame rate
between 60 and 100 fps. End-systole was defined by the aortic valve
closure in the apical long-axis view. The LA endocardial border was
manually traced and the region of interest was adjusted to the thickness
of the LA wall [8] . Left atrial reservoir strain was
measured as the peak positive longitudinal strain during ventricular
systole [9] (Figure 1) . All measurements were
performed by an experienced operator. To determine the interobserver
variability, all measurements were repeated by a second operator blinded
to the values obtained by the first operator.
Statistical analysis:
Data were analyzed using the statistical package for the Social Sciences
(SPSS) version 25 (IBM Corp., Armonk, NY, USA). Data was summarized
using mean and standard deviation for quantitative variables.
Qualitative data were expressed as frequency and percentage. Comparisons
between groups were done using unpaired t test. Multivariant Logistic
regression was done to detect the predictors of AF. Receiver operating
characteristic (ROC) curve was used to identify optimal cut-off values
of LA strain for prediction of AF. Area Under Curve (AUC) was also
calculated. Criteria to qualify for AUC were as follows: 0.90 – 1 =
excellent, 0.80-0.90 = good, 0.70-0.80 = fair; 0.60-0.70 = poor; and
0.50-0.6 = fail. The optimal cutoff point was established at point of
maximum accuracy. p <0.05 was considered significant.
Results:
Patients’ demographics and clinical data:
A total of 132 patients with DCM were evaluated. Thirty-two patients
were excluded due to the presence of organic valvular disease (n = 16),
prosthetic valve (n = 9), and poor image quality (n = 7). The final
study population comprised 100 patients who were classified into 2
groups based on the rhythm whether sinus or atrial fibrillation.
Demographic variables and risk
factors are presented in (table
1) . Group II had significantly
greater heart rate (88.48±5.13 vs. 78.04±6.21 bpm; P <0.001).
3.2. Echocardiographic parameters:
LA diameters (anteroposterior, longitudinal and transverse) were
significantly greater in group II
(5.37±0.38 vs. 4.53±0.29 cm; 6.79±0.40 vs. 6.23±0.30 cm and 5.6±0.38 vs.
4.72±0.31 cm, respectively, P < 0.001). Also, LA volumes
(maximal and minimal) were significantly greater in group II
(128.2±24.53 vs. 97.34±20.45 ml and
84±19.11 vs. 68.52±23.54 ml,
respectively, P <0.001). While, LA emptying fraction was
significantly lower in group II
(27.76±4.54 vs. 36.24 ±3.47 %; P
< 0.001).
There was no significant statistical differences between both groups as
regarding left ventricular end systolic volume (LVESV), left ventricular
end diastolic volume (LVEDV) and left ventricular ejection fraction
(LVEF) (130.74±11.28 vs. 129.66±19.01 ml; P =0.730, 158.70±12.43 vs.
166.88±26.46 ml; P =0.051, and 30.90±3.63 vs. 29.94±4.28 %; P =0.229) ;
respectively.
Left atrial longitudinal strain was significantly reduced in group II
(7.55 ±1.59 vs. 19.83 ±3.26; P <0.001) (table 2) .
Inter-observer variabilities were 4.6 ± 2.8% for LA emptying fraction,
3.6 ± 1.1% for LVEF, and 5.6 ± 3.1% for LA longitudinal strain.
Left Atrial diameters, volumes and function indexes showed significant
differences between AF and SR group, as anteroposterior, longitudinal,
transverse LA diameters, LAVmax and LAVmin were significantly greater in
the AF group, whereas LAEF and PALS were significantly lower in AF group.
Multivariate logistic regression analysis showed that LA longitudinal
strain (OR 0.322, 95% CI 0.206–0.503, P < 0.001) and LAVmin
(OR 0.922, 95% CI 0.855–0.993, P < 0.033) were independent
predictors for AF occurrence in DCM patients.
The receiver-operator
characteristic (ROC) curve showed that LA longitudinal strain cut-off
value <11.1% has the best diagnostic accuracy (sensitivity =
96%; specificity = 95.3%) in predicting presence of atrial
fibrillation in DCM patients (AUC 0.982, 95% CI 0.959–1.0, P
< .001) (Figure 2) .
Discussion :
Development of AF in patients with dilated cardiomyopathy is an
independent marker of worse outcome. Previous studies demonstrated that
new onset AF in the setting of cardiomyopathy was independently
predicted by a more severe left ventricular dysfunction and a more
dilated left atrium [10] .
Normal ranges for LA deformation and cut-off values to diagnose LA
dysfunction with different diseases have been reported, but data are
still conflicting [4] . Therefore, we aimed at evaluating
the correlation between left atrial strain and the occurrence of AF in
patients with DCM and to detect a cut-off value that can predict
presence of atrial fibrillation in this group of patients.
The present study demonstrated that PALS which represent the dynamic
reservoir function of LA was impaired in DCM patients and it is more
significantly lower in AF group. Multivariate logistic regression showed
that PALS and LAVmin were independent predictors for the presence of AF
in patients with DCM. Also, we demonstrated that LA longitudinal strain
cut-off value <11.1% has the best diagnostic accuracy
(sensitivity = 96%; specificity = 95.3%) in predicting presence of
atrial fibrillation in DCM patients (AUC 0.982, 95% CI 0.959–1.0, P
< .001). Therefore, we can use left atrial longitudinal as a
simple measure to detect DCM patients at risk to develop AF. Similarly,
Kurzawski et al. [11] demonstrated that LA conduit strain
less than 5.43% and contractile less than − 1.97% distinguished sinus
rhythm from AF in patients with LVEF <25%.
Motoki et al. [12] demonstrated that total LA strain
< 23.2% was an independent risk factor for AF recurrence in
256 patients with preserved LVEF after ablation due to AF.
LA strain and strain rate during ventricular systole is a marker of
atrial distensibility and can be used as an index of LA reservoir
function [13] . Left atrial strain is a strong and
independent predictor of AF recurrence after catheter ablation of
paroxysmal AF in patients with preserved EF [14] . Schotten
et al. [15] demonstrated that atrial compliance is impaired
by AF even before structural remodeling.
One of the other important predictors of new onset AF in HF patients is
LA size. Increased LA volume is associated with a greater risk of AF in
elderly, hypertrophic cardiomyopathy, and HF [16] . This
study demonstrated that LA diameters and volumes were significantly
greater in patients with AF. Moreover, LA minimal volume was found to be
a good predictor of AF presence in patients with DCM. However LA
emptying fraction (LAEF) was significantly lower in AF group. Matei et
al. [17] found that increased LA diameters proved to be
good predictive factors for the presence of permanent AF in a group of
348 DCM patients with sinus rhythm who followed for a mean of 60 months.
Similarly, Tuomainen et al. [18] showed a significant
increase in LA anteroposterior diameter in AF patients in the setting of
DCM. Cho et al. [19] reported that patients who developed
new AF had larger LA dimensions and volumes with lower LAEF.
Limitations:
Our study had some limitations. Firstly, the sample size was relatively
small. Secondly, the lack of standardization in the left atrial strain
measurement together with differences in software between manufactures.
Moreover, there is no dedicated software for atrial strain and all
calculations were performed by the software initially dedicated for the
left ventricle.
Conclusion:
Left atrial longitudinal strain was significantly reduced in AF in the
setting of DCM. LA longitudinal strain and LAVmin are independent
predictors for AF occurrence in this group of patients with LA strain
values <11.1% can be used to predict AF in DCM.
Author contributions:
Al-Shimaa Mohamed Sabry: Concept/design, Data analysis/ Drafting
article.
Hesham Mohamed Abo El-Enin: Critical revision of article.
Taha Motamed Abdelwahab: Data collection and statistics.
Hany Hasan Ebaid: Data interpretation, revision of article.
References:
- Aleksova A, Merlo M, Zecchin M, et al: Impact of Atrial Fibrillation
on Outcome of Patients with Idiopathic Dilated Cardiomyopathy: Data
from the Heart Muscle Disease Registry of Trieste. Clinical Medicine
& Research 2010: 8(3-4):142–9.
- Lee PK and Anter E: Atrial Fibrillation and Heart Failure: A Review of
the Intersection of Two Cardiac Epidemics. Journal of Atrial
Fibrillation 2013:6(1):751.
- Garg A and Akoum N: Atrial fibrillation and heart failure. Current
Opinion in Cardiology 2013: 28(3):332–336.
- Rimbaş RC, Dulgheru RE, & Vinereanu D: Methodological Gaps in Left
Atrial Function Assessment by 2D Speckle Tracking Echocardiography.
Arquivos brasileiros de cardiologia 2015: 105(6):625–636.
- Lang RM, Badano LP, Mor-Avi V, et al: Recommendations for cardiac
chamber quantification by echocardiography in adults: an update from
the American Society of Echocardiography and the European Association
of Cardiovascular Imaging. European Heart Journal - Cardiovascular
Imaging 2015:16(3):233–71
- Wharton G, Steeds R, Allen, J, et al: A minimum dataset for a standard
adult transthoracic echocardiogram: a guideline protocol from the
British Society of Echocardiography. Echo Research and Practice 2015:
2(1):9–24.
- Nistri S, Galderisi M, Ballo P, et al: Determinants of
echocardiographic left atrial volume: implications for normalcy.
European Journal of Echocardiography. 2011:12:826-33
- Badano LP, Kolias TJ, Muraru D, et al: Standardization of left atrial,
right ventricular, and right atrial deformation imaging using
two-dimensional speckle tracking echocardiography: a consensus
document of the EACVI/ASE/Industry Task Force to standardize
deformation imaging, European Heart Journal - Cardiovascular Imaging
2018: 19(6):591–600.
- Cameli M, Lisi M, Righini FM, et al: Novel echocardiographic
techniques to assess left atrial size, anatomy and function.
Cardiovasc Ultrasound 2012: 10:4.
- Aleksova
A,
Merlo
M,
Zecchin
M, et al: Impact of Atrial Fibrillation on Outcome of Patients with
Idiopathic Dilated Cardiomyopathy: Data from the Heart Muscle Disease
Registry of Trieste.
Clin Med
Res. 2010: 8(3-4): 142–149.
- Kurzawski J, Sadowska AJ, Gackowski A, et al: Left atrial longitudinal
strain in dilated cardiomyopathy patients: is there a discrimination
threshold for atrial fibrillation? The International Journal of
Cardiovascular Imaging 2018: 35:319–325
- Motoki H, Negishi K, Kusunose K, et al: Global left atrial strain in
the prediction of sinus rhythm maintenance after catheter ablation for
atrial fibrillation. Journal of the American Society of
Echocardiography 2014: 27(11):1184-92.
- Inaba Y, Yuda S, Kobayashi N, et al: Strain rate imaging for
noninvasive functional quantification of the left atrium: comparative
studies in controls and patients with atrial fibrillation. J Am Soc
Echocardiogr 2005: 18:729–36.
- Vrsalovic M, Hummel S, Ghanbari H, et al: Left atrial strain predicts
atrial fibrillation recurrence in patients with paroxysmal atrial
fibrillation and preserved ejection fraction treated with catheter
ablation. JACC 2015: 65(10): doi: 10.1016/S0735-1097(15)61205-0.
- Schotten U, de Hann S, Neuberger HR, et al: Loss of atrial
contractility is primary cause of atrial dilatation during first days
of atrial fibrillation. Am J Physiol Heart Circ Physiol 2004:
287:H2324–31.
- Tsang TS, Barnes ME, Gersh BJ, et al: Risks for Atrial Fibrillation
and Congestive Heart Failure in Patients ≥ 65 Years of Age with
Abnormal Left Ventricular Diastolic Relaxation. Am J Cardiol 2004:
93:54–8.
- Matei C, Pop I, Badea M, et al: Predictive Factors for Atrial
Fibrillation Appearance in Dilated Cardiomyopathy. Romanian Journal of
Cardiology 2012: 22(2):97-106.
- Tuomainen PO, Magga J, Fedacko J, et al: Idiopathic Dilated
Cardiomyopathy and Chronic Atrial Fibrillation. Clinical Physiology
and Functional Imaging 2013: 34(2):133–7.
- Cho GY, Jo SH, Kim MA, et al: Left Atrial Dyssynchrony Assessed by
Strain Imaging in Predicting Future Development of Atrial Fibrillation
in Patients with Heart Failure. International Journal of Cardiology
2009: 134(3):336–41.