Echocardiographic Predictors of Symptomatic Atrial Fibrillation In Patients with Rheumatic Mitral Stenosis and Normal Sinus Rhythm
Credits:Fahriye Vatansever Agca1,Ozan Kinay1,Mustafa Karaca2,Muge Ildizli Demirbas2,Serdar Biceroglu2,Baris Kilicarslan1,Cem Nazli 1,A. Oktay Ergene1
1 Ataturk Training and Research Hospital Cardiology Department,2 Atakalp Heart Hospital Cardiology Department,Turkey
of Correspondence:Mustafa Kraca,Atakalp Kalp Hastanesi,1418 sok.No.:16,Kahramanlar ,Turkey.
state that they have no interests which may be perceived as posing a conflict
doi : 10.4022/jafib.v1i1.394
mitral stenosis (RMS) increases the risk of both atrial fibrillation (AF) and
thromboembolism. Methods: Patients with mitral stenosis and normal sinus rhythm
were enrolled in the study prospectively.The present study was designed to
study whether echocardiographic evaluation in patients with mitral stenosis and
normal sinus rhythm could predict the occurrence of symptomatic AF . Results:
Sixty-two patients (51 females) with mitral stenosis and normal sinus rhythm
were included in the study. Seven patients (11.3%) developed symptomatic AF and
the remaining 55 were free of AF during a followed-up of 22±5 months. The
following echocardiographic parameters were significantly increased and
predicted the development of AF; left atrial (LA) mediolateral diameter (5.5 ± 0.5 cm vs 4.7 ± 0.7 cm), right atrial mediolateral diameter (4,7 ± 1.0 cm vs 3.6 ± 1.3 cm), LA area in the apical two chamber view ( 31 ± 3.2 cm2 vs 25 ± 5.8 cm2),
right atrial volume (52 ± 22 cm3 vs 34 ± 19 cm3), and interatrial conduction
time (IACT) (142 ± 22 msec vs 115 ± 16 msec). Conclusion: This study revealed
that echocardiography can be used to predict symptomatic AF in patients with
RMS and sinus rhythm.
rheumatic mitral stenosis (RMS), mitral valve area is reduced, creating an obstruction
to the blood flow between the left atrium (LA) and the left ventricle (LV),
causing an elevation in LA pressure. Elevation in LA pressure has several
important effects including enlargement of the LA, atrial arrhythmias, and an
increase in pulmonary venous pressure. RMS increases the risk of both atrial
fibrillation (AF) and thromboembolism, causing an important health care problem
in developing countries. The prevalence of AF in patients with MS is between
17 to 80% and related to both the severity of valve obstruction and patient age
. The incidence
of systemic embolism is greater in rheumatic mitral valve disease than in any
other common form of valvular heart disease.
with AF and mitral stenosis have high incidence of thrombus formation in the LA
[,]. AF is the most commonly
encountered cardiac arrhythmia in this subset of patients with an increased risk of thromboembolism . Although mitral
stenosis is considered as a strong risk factor for AF, the parameters in mitral
stenosis that predict the risk of future AF have not been determined.
Echocardiography is the primary and relatively simple tool to follow up the
patients with RMS. AF is generally associated with structural changes in the
atria and echocardiography provides a detailed anatomical evaluation. In
addition, flow characteristics and chamber pressure can also be detected by
aim of the present study was to investigate cardiac parameters that may predict
prospectively in preceeding symptomatic AF in patients with mitral stenosis and
normal sinus rhythm. Clinical and
echocardiographic parameters were studied in prediction of AF.
with mitral stenosis and normal sinus rhythm have been selected prospectively
among a total of 1512 patients seen in our out-patient clinic between July 2003
and July 2004. Any patient with a new or previous diagnosis of mitral stenosis
was evaluated for the study. Patients with a history of AF or valve disease
other then RMS (with an exception of mild tricuspid or pulmonary valve
regurgitation), who had undergone valve replacement, or those with poor echocardiographic
images were excluded. None of the patients included in this study were on
anti-arrhythmic drugs. The initial evaluation of the patients included history,
physical examination, electrocardiography (ECG) and trans-thoracic
echocardiography. At the end of the follow-up, patients were grouped into those
who developed AF (group 1) and those who were free from AF (group 2).
evaluation was performed by transtohoracic approach (General Electrics-Vivid 3
USA) and included standard parameters and atrial volumes, mitral valve area, transmitral
pressure gradient and interatrial conduction time (IACT).
volumes were calculated by the ellipse formula: Atrial volume: 4 Π /3
x D1/2 x D2/2 x D3/2, where D1
(mm) is anteroposterior, D2 mediolateral and D3
superoinferior dimension . The anteroposterior
dimension of the left atrium (LA) was measured in the parasternal view, and the
mediolateral and superoinferior dimensions of LA were measured in the apical
four-chamber view. For the right atrium (RA), the mediolateral diameter was
used for both D2 and D3
in the formula. Mitral valve area was calculated by planimetry and the pressure
Interatrial conduction time was defined as the
time interval between the onset of the P-wave and the LAA (left atrial
appendage) ejection flow . After the apical
two-chamber view was obtained, the transducer was angulated anteriorly until LAA came into the view. A pulse
Doppler sample volume in 1/3 proximal portion of LAA was used to obtain
flow recordings. The ECG was recorded simultaneously via a single lead. The IACT was measured as the time interval between
the beginning of the P wave on the ECG and the onset of LAA flow. The mean IACT value over 5 cardiac cycles was used
in the data analysis ().
Figure 1 RInteratrial conduction time is calculated as the time interval between the beginning of the surface p wave and the onset of LAA ejection flow. (LV: Left Ventricle, LA: Left Atrium, LAA: Left Atrial Appendage ).
patients in the study were followed up with clinical evaluation every three
months. The patients were asked to visit their primary physician if they
experienced any palpitations. Patients who reported palpitations at their
follow-up visits were subjected to 24-hour Holter monitoring. Episodes of AF
were defined to be relevant if they exceeded duration of 30 seconds per day and
coincided with the symptoms. The patients who underwent cardiac surgery have
not been excluded from the study but not been followed-up for further.
Percutaneous valvuloplasty was not a criterion for exclusion from the study or from
Mann-Whitney U test was used for comparison of data between those with AF and
without AF. Multiple logistic regression analysis was used to assess whether
clinical and echocardiographic parameters and IACT
were related to AF occurrence. Spearman’s test was used to detect whether any of the assessed parameters correlated with AF
occurrence. P value less than .05 was regarded as significant.
total of 64 patients (11 males and 53 females) with mitral stenosis and normal
sinus rhythm were initially enrolled in the study. Two patients were excluded
from the study due to poor visualization of LAA by trans-thoracic
echocardiography. The remaining 62 patients were followed prospectively for a
mean period of 22±5 months. Seven (11.3%, 7/62) patients developed symptomatic
AF during follow-up and were assigned to Group 1. Six of the group 1 patients
were demonstrated to have an AF episode by ECG recordings obtained when they
were admitted to an emergency room due to palpitations. 10 patients presented
palpitation and received Holter monitoring. A mbulatory
Holter ECG monitoring revealed an AF episode in one patient. Group 2 consisted
of the remaining 55 (88.8%) patients who did not develop AF during
follow-up. The demographics, drug usage,
and other characteristics of the patients are listed and compared between
groups (). Age, functional capacity and
follow-up periods were similar between groups. During the follow-up period,
eight patients underwent percutaneous mitral balloon valvuloplasty. One patient
had anterior myocardial infarction. Six patients underwent mitral valve surgery
and were not followed-up further. In these patients, the mean time of follow-up
from the time of inclusion to the surgery was 13±6 months in those patients. No
other major cardiac events have been reported.
Table 1 The comparison of the demographics and patient characteristics between groups. (CVA: Cerebrovascular accident).
basal echocardiographic parameters of the study population are summarized in . Mitral valve area, trans-mitral pressure gradients, the
degree of mitral regurgitation, LA volume, LA and RA superoinferior diameters
and volumes obtained in apical 4-chamber and 2-chamber views did not differ
between the groups. However, the following four echocardiographic parameters
were found to be associated with AF occurrence: left atrial mediolateral
diameter (LAML2), right atrial mediolateral diameter (RAML2),
right atrial volume (RAV) in apical 4-chamber view, and left atrial area in
apical 2-chamber view (LA area3). Those parameters were found to be
independent predictors of symptomatic AF.
statistically significantly prolonged in group 1 (Mean IACT value was 142 ± 22 msec in group 1, 115 ± 16 msec in group
2, p = 0.04). No significant correlation was detected between IACT and other AF-predictive
Table 2 Comparison of echocardiographic parameters and interatrial conduction time between groups.
the best of our knowledge this is the first prospective study that
determined the echocardiographic parameters that predict symptomatic AF in
patient with rheumatic mitral valve disease and sinus rhythym. Previous
studies have provided information about AF recurrence or have compared chronic
AF patients to control subjects with a normal sinus rhythm . Some clinical,
electrocardiographic and echocardiographic parameters have been proposed as
predictors of AF recurrence such as advanced age, left atrial enlargement and
structural heart disease, although the results are conflicting [,]. The role of left atrial
diameter in predicting AF remains controversial. Kinay et al found no
significant difference in left atrial diameter in patients with and without
recurrent AF .
In contrast, Diker et al has suggested that age, left atrial diameter and mean
trans-valvular gradient may predict AF occurrence in their retrospective study . In our study, left and
right atrial mediolateral diameters at apical 4-chamber view were significantly
large in group 1. But only the volume of right atrium was found to be
significantly high in group 1. This can be explained by that the mediolateral
diameter of the right atrium has been used for both D2 and D3 in the volume formula.
Additionally, an eccentric enlargement of the atria can also contribute these
appears to be predictive of AF recurrence only in patients older than 70-year
old . However, age cannot be
considered as a predictive parameter for AF recurrence in patients with mitral
presence of an interatrial conduction delay has been shown to be associated
with occurrence and recurrence of AF and some authors claim that clinically
reducing interatrial conduction time via bi-atrial pacing could reduce AF
recurrences in patients with interatrial conduction delay . Interatrial conduction
delay may endorse AF by facilitating micro-reentry circuits . There is an ongoing
debate concerning the mechanism of these issues. A standard non-invasive method
of measuring interatrial conduction time is missing. Fuenmayor et al
demonstrated that IACT measured invasively by electrode catheters, correlated
with IACT measured by trans-thoracic echocardiography as the time interval from
the beginning of the P wave to the beginning of the mitral A wave . Dilation of LA
structures in patients with mitral stenosis makes it easy to view the LAA by
trans-thoracic echocardiography, abolishing the need of more invasive trans-esophageal
echocardiography . Although an
electrophysiological test has not been performed in our patients, a significant
correlation between IACT and
electrophysiological IACT was previously reported by our group . In this study, IACT determined by trans-thoracic
echocardiography correlated with symptomatic AF occurrence in patients with
mitral stenosis, independent of any other clinical and echocardiographic
parameters. Kinay et al. found that IACT
was prolonged in patients with recurrent AF
. But our study reveals
that IACT has been prolonged before the episodes of symptomatic AF have been
There are conflicting results regarding whether enlarged
atrial diameter predicts AF or occurs as a result of atrial remodeling due to
AF. The present results support that atrial enlargement may be a
structural substrate enabling symptomatic AF to occur. However large scale
studies are needed to confirm this hypothesis.
design of our study does not include those patients without symptom due to AF,
since we detected episodes of AF based on the symptoms. None of the patients who
developed AF was detected coincidently. This may cause underestimation of the
patients with AF, and the patients with asymptomatic AF will be listed in group
2, instead of group 1. This will reduce the power of the statistics. For these
reasons, conclusions of our study can not be applied to asymptomatic AF
patients with MS. Asymptomatic AF is a clinical challenge and causes
underestimation of the incidence of AF in clinical studies. The incidence of
asymptomatic patients has been reported to be 17%  In the literature,
absence of symptoms are escpecially evident in old patients. In contrary, the
average age of the patients in our study is around 40 and represents a relatively
young population. Fortunatelly, the patients with mitral stenosis are tent to
be symptomatic when they develop AF, since rapid heart rate causes relatively
more hemodynamic deterioration. On this assumption and according to the above
data, we expect less asymptomatic patients with AF in this particular group on
comparison to general AF population. Termination of the follow-up of the
patients who underwent the surgery may interfere the results. Following surgery
the incidence of AF due to pericardial irritation reaches 50% in some series
with normal LA. Finally, due to the limited number of the subjects studied and
short time of follow-up, effects of gender, age, and surgery could not be
conclusion, the present study showed that echocardiographic IACT measurement and the other four
echocardiographic atrial parameters may
predict the development of symptomatic AF in patients with mitral stenosis and
sinus rhythm. These parameters may point out the group of patients prone to symptomatic
AF and those who need close clinical follow-up. These parameters may be new
targets for studies to address novel approaches to identify patients who
require additional attention and modified treatment, such as early
anti-coagulation and anti-arrhythmic medications. Large scale studies are
necessary before making a certain comment on these issues.
patients with rheumatic mitral valve disease and sinus rhythm still has a
substantial risk of systemic embolism and is, therefore, they are possible
candidates for long-term warfarin therapy. There are no reliable clinical
markers in such cases. Based on our study, prolonged IACT and enlarged atrial
diameter can be used to select a subgroup of patients who may actually benefit
from anticoagulant therapy in patients with RMS and sinus rhythm.
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