Thromboembolic events are a major cause of morbidity and mortality in patients of mitral stenosis (MS).^1,2 While LA/LLA thrombus formation has been reported in 33 % patients of rheumatic mitral stenosis in atrial fibrillation ³,it has also been reported in 6.6-13.5% in patientsof MSpatients in normal sinus rhythm (NSR)^4,5,6,7.

The left atrial appendage (LAA) is the most common site of thrombus formation. The stasis of blood flow in LAA, which occurs in the absence of forcible atrial contraction during AF, initiates the clot formation process and leads to the occurrence of arterial thromboembolic events.^7,8Serkan et al.⁶ in an interesting study, have shown that in patients of severe MS, there is an impairment of LA/LAA contractility to a similar extent, irrespective of whether a patient is in SR or AF. Impairment of LA/LAA contractility leads to stasis of blood with the formation of smoke in LA/LAA(LASEC), which in turn has been found to be a positive predictor of LA/LAA thrombus in patients of severe rheumatic MS in NSR.^7,9,10,11 A number of small studies have also reported that patients with severe rheumatic MS (RMS) in normal sinus rhythm (NSR) with associated LASEC have raised atrial and systemic levels of procoagulants. ^9,12,13

However, a large Indian study by Manjunath et al⁴ has reported that LASEC is not an independent predictor of thrombus formation in patients of rheumaticMS in SR. Hence, the ACC/AHA 2020 guideline on valvular heart disease¹⁴ still does not recommend oral anticoagulants in patients of severe rheumatic MS in NSR with associated LASEC. Manjunath et al⁴ also reported that thrombus incidence was 6.6 % in MS in NSR and they were associated with LASEC.They did not study the procoagulant levels in these MS patients in NSR with LASEC and associated LAA inactivity. Stasis of blood (LASEC being a marker of stasis) and hypercoagulable state are prerequisites for thrombus formation. Therefore, we hypothesized thatpatients of severe MS in NSR with LAA inactivity with associated LASEC have a hypercoagulable state comparable to patients of severe MS in atrial fibrillation.

This was a prospective observational study conducted from August 2021 to January 2023 at the Govind Ballabh Pant Institute of Postgraduate Medical Education and Research (GIPMER) and Maulana Azad Medical College (MAMC), New Delhi.

The study aimed to assess and compare the level of procoagulants between patients of severe rheumatic MS in NSR with LAA inactivity and associatedleft atrial spontaneous echo contrast versus those of severe mitral stenosis with atrial fibrillation. The ethics committee at our institution approved this study, and all patients provided written informed consent.

Primary and secondary objectives

The primary objective was to assess the level of procoagulant prothrombin fragment 1+2 (PF1+2) in the left atrium and peripheral blood of patients of rheumatic MS in NSR with associated LASEC compared MS in AF. The secondary objectives were to assess the level of plasminogen activator inhibitor- PAI (marker of fibrinolytic system activation), fibrinogen, and D dimers compared to MS in AF.

Sample size: It was an exploratory study to assess and compare the level of procoagulants between two groups of patients compared to healthy controls; Group I: patients of severe rheumatic mitral stenosis in sinus rhythm with left atrial appendage inactivity and associated smoke; Group II: patients of severe rheumatic mitral stenosis in atrial fibrillation. As it was a pilot study, we decided to study a total of 105 subjects; 35 patients of severe rheumatic MS in sinus rhythm, 35 patients of severe rheumatic MS in atrial fibrillationand 35 healthy controls.

Patients

The participants in the study group were men or women with an age greater than 18 years with severe rheumatic MS {mitral valve area (MVA) ≤ 1.5 cm² by planimetry} and a valve suitable for balloon mitral valvuloplasty and associated LAA inactivity.

Patients were excluded from the study if they had LA/LAA thrombus on echocardiography, paroxysmal AF atrial fibrillationin patients of MS in NSR,coexisting left ventricular dysfunction (ejection fraction <50%), congenital heart disease, or any contraindication for transesophageal echocardiography (TEE).Patients were also excluded if they haddiabetes mellitus, hypertension, renal or hepatic dysfunction, overt malignancy, pregnancy, chronic inflammatory disease such as systemic lupus erythematosus, rheumatic arthritis, human immunodeficiency virus infection, a history of systemic or pulmonary embolism, or an associated COVID-19 infection.

Controls30 healthy volunteers were taken as controls for the study. The controls had no echocardiographic evidence of structural heart disease, were in sinus rhythm, and had all other exclusion criteria identical to those of the study patients.

Transthoracic echocardiography

 All patients underwent detailed Trans Thoracic Echocardiography in order to evaluate valvular involvement in the study group and to exclude cardiac disease in control subjects using Philips EPIQ 7C fitted with a commercially available 5 MHz transducer. Two-dimensional and Doppler echocardiographic studies were performed in the left lateral decubitus position in conventional views (parasternal long, short-axis, and apical two and four-chamber view) according to American Society of Echocardiography guidelines.¹⁵

All patients were evaluated using two-dimensional M-mode, pulsed- and continuous-wave Doppler echocardiography. The mitral valve area was calculated using planimetry and pressure half-time methods. Mean pressure gradient and pulmonary artery systolic pressure were also measured by Doppler studies. The left ventricular end-diastolic and end-systolic diameters, interventricular septum and posterior wall thickness, and left atrial diameter (LAD) were recorded from the parasternal long-axis view in M mode at the end of systole. The left ventricular ejection fraction was measured using the modified Simpson method in the apical 4 chamber method. Modified parasternal short-axis view (as described by Herzog et al¹⁶) was used to visualize the left atrial appendage. All echocardiographic examinations were performed at least 5 times for patients who were in AF¹⁷ and at least 3 times for patients with sinus rhythm and the mean values of the replicated measurements were recorded. Patients with severe MS (MVA<1.5 cm²) with concomitant mild and/or absent MR were included in the study.

Transesophageal echocardiography

A one-lead electrocardiogram was recorded continuously during the TEE (informed written consent was obtained from all patients before the multiplane TEE) using a Philips EPIQ 7C fitted with a commercially available 5 MHz X7-2t transducer at admission and on the day of the BMV procedure. The LA and LAA imaging were begun in the horizontal plane at 0°, then the transducer was rotated progressively to 60° and 90°, in the same plane, and images were also evaluated after a slight and more pronounced counterclockwise rotation of the probe. Rotation of the transducer to 110° and 130° was coupled with more pronounced counterclockwise rotation of the probe. All images were recorded by optimizing the gain settings to minimize gray-noise artefacts. We examined the LAA in the short and long axis. It has been shown that transesophageal echocardiography is highly sensitive for the detection of left atrial clot, especially in the left atrial appendage.¹⁸

LA or LAA thrombus was diagnosed by the presence of a clearly defined echogenic intracavitary mass different from the underlying endocardium. SEC was diagnosed by the presence of dynamic smoke-like echoes in the LA cavity and LAA with a characteristic swirling motion. Patients with LA/LAA thrombus were excluded from the study. The severity of SEC was graded from 0 to 4+ as proposed by Fatkin et al.¹⁹

Left atrial appendage (LAA) velocity

The LAA flow profiles were obtained by placing the sample volume of the pulsed Doppler 1 cm below the LAA orifice where there were no wall artefacts and a net flow could be recorded using pulse wave Doppler. The positive flow observed after the P-wave of surface ECG, was taken as LAA emptying velocity LAAEV, representing the LAA contractile function. Inactive LAA was defined as late peak LAAEV<25cm/sec.^20,21 LAAEV wad performed at least 5 times for patients who were in AF⁴⁹ and at least 3 times for patients with sinus rhythm. The mean values of the replicated measurements were recorded. All echocardiograms were independently evaluated by two observers and any difference of opinion was settled by mutual consensus.

24-hours holter ecg monitoring

After preliminary evaluation, eligible patients were subjected to 24-hour Holter ECG monitoring. We defined controlled ventricular rate as patients having average heart rate ≤100/min along with no individual rate >110% of maximum predicted heart rate for the age of the patient over a 24-hour period as was used in an AFFIRM trial.²² Patients who had baseline increased heart rate, were put on rate control medication such as beta blocker, calcium channel blocker or digoxin. They were reevaluated after one week. If their resting one-minute heart rate was <100 beats/minute, they were subjected to 24-hours Holter ECG monitoring,²³a day prior to balloon valvuloplasty. If the average heart rate (AHR) on 24 hours Holter ECG monitoring was <100 beats/minute, they were enrolled in the study and posted for balloon mitral valvuloplasty.

Anticoagulation

All patients of MS who met our study inclusion criteria and were on oral anticoagulation for AF were admitted and their oral anticoagulation was stopped at least 4 days before valvuloplasty.⁹They were put on low molecular weight heparin until 24 hours before BMV and prothrombin time with INR and aPTT were assessed in the morning 1-2 hours before the BMVand TEE.Patients with normal INR and aPTT were posted for percutaneous mitral balloon valvuloplasty.

Valvuloplasty procedure

In the catheterization laboratory, introducer sheaths were inserted into the right femoral artery and vein. A 6F polymer pigtail catheter was inserted into the left ventricle for pressure measurement. A transseptal puncture was performed with the help of a Brocken borough needle in an 8F Mullin sheath, and the mitral valve was dilated with an Inoue balloon. No thromboembolic events occurred in any patient during or after the valvuloplasty procedure.²⁴

Blood sampling

Prevalvuloplasty peripheral blood samples were drawn from a femoral vein sheath and immediately transferred to an EDTA tube containing 3.8% sodium citrate. Immediately after transseptal puncture, left atrial prevalvuloplasty samples were withdrawn from all 70 patients through the transseptal catheter (Mullin of Fast Cath), after at least twice the dead space volume was withdrawn and collected before administration of heparin. In controls, peripheral venous blood samples were collected through a needle puncture after the initial 3 mL of blood was discarded. Blood samples for procoagulants were immediately (within 2 hours) centrifuged at 3000 x g for 15 minutes, and the collected plasma was stored at -70°C in several aliquots in our biochemistry laboratory.

Hematological investigation

Baseline laboratory tests [(hemogram, erythrocyte segmentation rate, C reactive proteins renal function tests, liver function tests, PT (prothrombin time), aPTT, fibrinogen and platelet count)] were done in all subjects of our study (cases and controls).

Assay procedure

Peripheral venous samples of the control for measuring levels of plasma coagulation parameters, including PAI-1and PF1 + 2 were drawn in the morning between 8 and 10 AM. Samples were taken using 21-G vacuum tube phlebotomy needles into 3.8% 1:9 trisodium citrate-containing tubes, without venous stasis. Both left atrial blood and femoral vein samples of patients were taken during BMV before administration of heparin and immediately transferred to 3.8% 1:9 trisodium citrate containing tubes. The plasma was separated by centrifugation of blood (3000 x g for 15 min), and stored in several aliquots at -70°C until used for assay.

Plasma PF1+2concentration, used as a marker of in vivo thrombin generation, was measured using a quantitative sandwich enzyme- linked immunosorbent assay method (ELISA KIT, Elabscience USA, normal human plasma values: 31.2– 2000 pg/ml; intra- and inter coefficient of variation < 10%).PAI-1, used as a marker of endogenous fibrinolytic activity, was measured using a quantitative sandwich enzyme -linked immunosorbent assay (Elabscience, USA; normal plasma value is 5–40 ng/ml; intra- and inter-assay of coefficient of variation are < 10%). Plasma fibrinogen was assayed by the direct chromogenic method. D-dimer was measured with a particle-enhanced immunoturbidimetric method.The analysis of plasma samples was done in the Biochemistry Department of our hospital in a blinded manner.

Statistical analysis

The presentation of the Categorical variables has been presented as number and percentage (%). On the other hand,the quantitative data have been presented as the means ± SD and as median with 25th and 75th percentiles (interquartile range). The data normality was checked by using Kolmogorov-Smirnov test. The cases in which the data was not normal, we used non parametric tests. The following statistical tests were applied for the results.

1. The comparison of the variables which were quantitative and not normally distributed in nature were analysed using Mann-Whitney Test (for two groups) and Kruskal Wallis test (for more than two groups) and variables which were quantitative and normally distributed in nature were analysed using independent T test (for two groups) and ANOVA (for more than two groups). For all normally distributed value, a Post Hoc test (Bonferroni correction) was applied.For all not normally distributed data, a Post Hoc analysis by Dunn’s multiple pairwise comparison test was carried out. Paired t test/Wilcoxon signed rank test was used for comparison between peripheral blood and left atrial blood.
2. The comparison of the variables which were qualitative in nature were analysed using Chi-Square test. If any cell of a contingency table had an expected value of less than 5 then Fisher’s exact test was used.

The data entry was done in the Microsoft EXCEL spreadsheet and the final analysis was done with the use of Statistical Package for Social Sciences (SPSS) software, IBM manufacturer, Chicago, USA, ver 25.0.

For statistical significance, p value of less than 0.05 was considered statistically significant.

The study was conducted from August 2021 to January at Govind Ballabh Pant Institute of Post graduate Medical Education and Research (GIPMER), in New Delhi and enrolled, 35 patients with severe rheumatic MS patients in NSR, 35 patients with severe rheumatic MS patients in Atrial fibrillation and 35 healthy controls. Demographic clinical and hematological characteristics of the overall study population were summarized in table 1. No statistically significant differences were observed in term of age, sex,body mass index, hematological parameters. There was no significant difference in the percentage of patients in NYHA class II, class III or class IV between two patient’s groups. Most patients in both groups were in NYHA II and III (97.14% in MS in NSR vs 94.28% in MS in AF: p>0.5). We also measured mean left atrial pressure in all patients during BMV just after interatrial septal puncture and before balloon dilatation of mitral valve and there was no significant difference between these two groups. All patients in our study underwent 24 hours Holter monitoring and average heart was measured in each patient and found that no significant difference was between patient’s groups.

In our study, we took patients of severe mitral stenosis (MVA<1.5 cm2) in both study groups and echocardiographic characteristics was summarized in table2. There was no significant difference in mitral valve area between two groups (0.85±0.2 cm2 in MS in NSR and 0.84±0.12cm2 in MS in AF, p=0.87). Mean gradient, left atrial diameter, left ventricular ejection function, and pulmonary artery systolic pressure were also comparable in both the groups (p=>0.5). Most patients (91%) in our study had grade 3+or 4+ LASEC in both study groups. We enrolled severe MS with NSR with LAA inactivity and mean LAAEV was found to be 16.38±4.04cm/second. In patients of severe MS in AF, we observed that all patients had LAAEV with mean LAAEV of 12.61±2.8. The mean LAAEV in patients with AF was significantly lower than patients in NSR (p<0.0001).Wilkins score in patients of MS in AF was significantly higher than MS in NSR suggestive of a more deformed valve apparatus in patients of MS with atrial fibrillation.

The levels of PF1+2 in left atrial blood, a marker of endogenous thrombin generation required to convert fibrinogen into fibrin was similar in between these two patient’s groups {9017(6228-10963.5) in sinus rhythm vs 7728.62 (5584.55-13748) in AF, P=0.91}(table 3),while Mean serum fibrinogen (precursor of thrombus formation) significantly higher in the left atrial blood of patients of MS in AF than those in normal sinus rhythm {4.03±0.100 in AF and 3.47 ±0.89 in NSR, P=0.015)}(table3).However the degree of inhibition of the fibrinolytic system as assessed by level of PAI-1 was seen to a similar extent in both groups of patients {(26.09 ± 8.18) in sinus rhythm versus (27.95 ± 17.26) in AF, p=0.056}(table3,), resulting in similar level of D-dimer in left atrium of both groups {290(110-590) in sinus rhythm and 180(80-1080) in AF, p=0.785.

Similarly, the systemic level of PF1+2 was increased in both groups of patients with MS compared to healthy controls suggestive of systemic hypercoagulable state.However, the level of PF1+2 was significantly higher in patients with AF compared to those patients in sinus rhythm {6256 (3017.5-10867.5) vs 2931(1780-7191.25); p= 0.048), suggestive of greater thrombin generation in the AF group than in the sinus rhythm group. This may be due to variable spillover of the procoagulants from left atrium (the primary site of activation of the coagulation system in patients of MS) into systemic circulation. (table 4).There was no significant difference in the level of fibrinogen in peripheral blood in patients of MS in sinus rhythm compared to those in atrial fibrillationHowever, the level of fibrinogen was significantly higher in both patient groups compared to controls suggestive of systemic hypercoagulable state (table 4).Apart from increase in thrombin generation, there was impairment of the fibrinolytic system in both groups. Systemic level of PAI-1 was increased in both groups of patients with MS compared to healthy controls suggestive of systemic impaired fibrinolytic system (table4, figure 4).However, the level of PAI-1 was higher in patients with AF compared to sinus rhythm (21.85±6.74 vs 15.11±6.74; p=0.006), due to variable spill over from left atria, resulting in similar level of D dimer in both patient groups (table 4).

 Values are presented as mean ± SD or median with interquartile range (25^th and 75^th percentile).

BMI, body mass index; NHYA, New York Heart association; HF, Herat failure; AHR, Average heart rate on 24 hours Holter ECG monitoring; SGOT, serum glutamic-oxaloacetate transaminases; SGPT, serum glutamate pyruvate transaminase; CRP, C- reactive protein; ESR, erythrocyte sedimentation score, INR, international normalized ratio; aPTT, activated partial thromboplastin clotting time.

Above echocardiographic quantitative date was presented as mean ± SD.

MVA, mitral value area measured via planimetry method; LAD, left atrial diameter measured during M mode; LVEF, left ventricular ejection fraction via simpson’s method; LAAEV; left atrial appendages empty velocity; PASP, pulmonary artery systolic pressure.

Values are presented as mean ± SD or median with interquartile range (25^th and 75^th percentile).

 PF1+2, prothrombin fragment 1+2; PAI-1, plasminogen activator inhibitor-1.

Values are presented as mean ± SD or median with interquartile range (25^th and 75^th percentile).

PF1+2, prothrombin fragment 1+2; PAI-1, plasminogen activator inhibitor-1.

To the best of our knowledge, this is the first study which has systematically evaluatedthe level of procoagulants in the left atrium of patients of severe rheumatic MS in sinus rhythm with LAA inactivity and associatedLASEC and compared these procoagulants level with patientsof severe rheumatic MS in AF.

As per Virchow’s triad^25,26,27,28the three factors required for formation of thrombus in a vessel are;

1. endothelial injury,
2. local blood stasis and
3. hypercoagulable state.

All the above three factors are responsible for formation of thrombus in patients of MS in AF. In all patients of MS with AF, injury to the endothelium in the left atrium has been documented.²⁹ Onset of AF leads to gross impairment of contractility of both LA and LAA leading to stasis of blood, which in turn leads to crosslinking of RBCs with fibrin forming smoke in LA/LAA.³⁰This LA/LAA smoke in turn leads to activation of coagulation system creating a hypercoagulable milieu in the left atrium and formation of thrombus.⁹A large number of observational studies have documented this hypercoagulable state in LA^9,31,32,33 and accordingly, to prevent thrombus formation, all guidelines like ACC/AHA¹⁴ recommend oral anticoagulants to all patients of MS with AF to prevent thrombus formation in LA and its devastating sequelae of systemic thromboembolism.

A subset of patients of MS in sinus rhythm also have been shown to satisfy Virchow’s triad^25,26,27,28 leading to an increased risk of thrombus formation in LA/LAA along with systemic thromboembolism. The reported incidence of systemic thromboembolism in patients of MS in sinus rhythm has been reported to be 6.6-13.5%, primarily affecting the young population in our country.^4,5,6,7As in patients of MS in AF, a similar degree of left atrial endocardial injury has been documented by electron microscopy in patients of MS in sinus rhythm.²⁹Secondly, LAA hypocontractility has been documented in 73% of patients of severe MS in sinus rhythm by us.³⁴We have also shown that LAA inactivity (stasis) is only independent predictor of LA/LAA smoke (LASEC) in this subset of patients satisfying the second criteria of Virchow’s triad in respect to local stasis.  Thirdly, a large number of small observational studies have also reported of a hypercoagulable state in the left atrium of patients of MS in sinus rhythm.^9,12,13Peverill et al⁹reported that LASEC is the only independent predictor of increased local activity of the coagulation system, irrespective of whether patients are in sinus rhythm or atrial fibrillation. The local level of procoagulant (PF1+2) was similar in patients of MS in AF(n=9) to those in sinus rhythm with LASEC (n=16).They also reported that plasma levels of PF1+2 in both left atrial and peripheral blood were significantly higher in patients of MS in sinus rhythm with LASEC than in patients without LASEC. Atak et al¹² reported that the left atrial level of PF1+2 was significantly higher in patients of MS in SR irrespective of LASEC. However, the peripheral level of PF1+2 was significantly increased only in LASEC positive patients compared to controls. Similarly,Ileri et al¹³ assessed TAT-III, a maker of thrombin generation in patient of MS in SR and reported peripheral venous plasma levels of TAT-III was significantly raised in LASEC positive patient.From the above study it is reported that patients with severe rheumatic MS with associated LASEC have significantly higher activation of procoagulants in left atrium than LASEC negative patients and these procoagulants is reflected to peripheral blood due to variable spill over only in LASEC positive patients either in sinus rhythm or AF.Therefore, in our study, we enrolled patients of severe MS with LASEC because this subset of patient has more local and systemic hypercoagulable state and a tendency towards thrombus formation.

In our study we reported that levels of procoagulants (PF1+2 and PAI-1) in left atrium were similar in patients of severe MS either in AF or sinus rhythm with LAA inactivity and associated LASEC (dense smoke grade 2+ - 4+).  We also reported these procoagulants levels were higher in systemic blood of severe MS in AF than the patients of severe MS with LAA inactivity and associated LASEC. Probably the reason behind is due to variable spill over from left atrium to peripheral blood. Fibrinogen acts the raw material during the process of thrombus formation and in our study, we found that serum fibrinogen level in left atrium in AF is higher than sinus patients due to more LAA stasis(P<0.0001), but the degree of fibrinogen getting converted to fibrin was similar in both groups, measured by PF1+2 level, marker of thrombin generation³⁰, in the left atrium of both patients’ groups was similar. During the process thrombus formation PAI-1³⁰, a marker of impaired fibrinolysis, is responsible for thrombus degradation and we also found that there was impaired fibrinolysis in this subset of patients and the level of PIA-I inhibiting degradation of fibrin was also similar in both groups. We thought therefore D-dimer, the end product of fibrin degradation was similar in both groups and reflecting both local and systemic hypercoagulable state in these subsets of patient in SR and comparable to AF.A previous study by Jamal et al²³ reported that procoagulant levels were related to ventricular rate and levels of procoagulants were reduced with control of ventricular rate in severe MS in AF.Thus, we sought to minimize the influence of this confounding factor by enrolling only patients of MS with controlled mean heart rate (<100 beats/min) and wefound that the average heart rate, measured by 24 hours holterwas similar in both groups of patients, removing the confounding factor for additional increase of procoagulants.

Oral anticoagulants are still not recommended by guidelines in patients of MS in sinus rhythm with LASEC (usually formed in patients with LAA inactivity). The ACC/AHA 2020 guideline on valvular heart disease ¹⁴ have not recommended oral anticoagulants in this group of patients stating there is no adequate evidence to recommend initiation of oral anticoagulation in this group of patients. This is based on a cross-sectional study from India by Manjunath et al⁴ who concluded that LA/LAA smoke is not an independent predictor of thrombus formation in patients of MS in sinus rhythm. However, in these studies also mentioned that all patients with LA/LAA thrombus had associated smoke in LA/LAA. We feel that longitudinal studies following patients of MS with LA/LAA smoke are needed to show the causative association of LA/LAA smoke with thrombus. Further, these studies have not evaluated the levels of procoagulants in this subset of patients of MS with LASEC.However, in agreement with the report of Peverill et al⁹ we have also shown that the result of local level of activation of the coagulation system along with inhibition of the fibrinolytic system producing a hypercoagulable state occurs to a similar extent in patients of MS in sinus rhythm with LASEC and associated LAA inactivity as in patients of MS with atrial fibrillation also fulfilling the third criteria for thrombus formation as per Virchow triad.We have also shown that in this subset of patients of MS in sinus rhythm there is also a systemic hypercoagulable state similar to that reportedin patients of MS in AF.

We feel that based on our study results; oral anticoagulants should be given to all patients of MS in sinus rhythm with LASEC until the local hypercoagulable milieu is altered by relieving the obstruction across the mitral valve. Studies have shown that relieving the obstruction across mitral valve by valvuloplasty decreases the left atrial afterload leading to improvement in LA/LAA contractility,^35,36,37decrease in stasis^37,38,39,40and decrease in level of procoagulants.^41,42,43 So, unlike atrial fibrillation where lifelong anticoagulants are required due to persistence of stasis in LA/LAA (due to hypocontractility induced by AF per se), anticoagulants in patients of MS in sinus rhythm can be withdrawn once LA/LAA contractility improves. Most of studies,^{35,36,37,38,39,40} have been reported that after BMV, LAA inactivity and LASEC are usually improved within 6 months. Hence, based on our study results we feel that oral anticoagulants should be routinely given to all patients of severe MS in NSR with LAA inactivity and associated denseLASEC till there is improvement in LA/LAA function following valvuloplasty/mitral valve surgery.

 Limitation of the study

1st limitation is a small, single center pilot study. 2^nd limitation is using low molecular weight heparin in patients of MS in AF, although we stopped it 24 hours before procedure, we did not estimate anti factor Xa assay due to cost and unviability of laboratory for testing. However, we enrolled those AF patients who had normal PT and aPTT.

There is activation of the coagulation system to a similar extent in patients of MS in sinus rhythm with LAA inactivity and associated LASEC (dense smoke; grade 2+ - 4+) compared to those of MS in atrial fibrillation. Hence, this subset of patients of MS in sinus rhythmshould also receive oral anticoagulants as is recommended for patients in MS with AF to prevents thrombus formation in left atrium, till left atrial appendage function improvement.

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