Research Article
Evaluation of Thromboembolism and Valve Thrombosis in Patients with Rheumatic Heart Disease Undergoing Mitral Tissue Valve Replacement in the Presence of Atrial Fibrillation with or without Left Atrial Clot: Review of A 17-Years’ Experience
Lakshmi Kumari Sankhyan1, Ujjwal Kumar Chowdhury1*, Adil Rizvi1, Suruchi Hasija2, Kartik Patel1, Sandeep Seth2, Abhinavsingh Chauhan1 and Mani Kalaivani3
1Department of Cardiothoracic and Vascular Surgery, All India Institute of Medical Sciences, India
2Department of Cardiac Anaesthesia, All India Institute of Medical Sciences, India
3Department of Biostatistics, All India Institute of Medical Sciences, India
*Corresponding author: Ujjwal Kumar Chowdhury, Department of Cardiothoracic and Vascular Surgery, All India Institute of Medical Sciences, New Delhi-110029, India
Published: 23 Aug, 2018
Cite this article as: Sankhyan LK, Chowdhury UK, Rizvi
A, Hasija S, Patel K, Seth S, et al.
Evaluation of Thromboembolism and
Valve Thrombosis in Patients with
Rheumatic Heart Disease Undergoing
Mitral Tissue Valve Replacement in
the Presence of Atrial Fibrillation with
or without Left Atrial Clot: Review of
A 17-Years’ Experience. World J Surg
Surgical Res. 2018; 1: 1042.
Abstract
Background and Aim: To evaluate the incidence of thromboembolism in patients implanted with
tissue mitral valves and to evaluate the risks and benefits of left atrial appendage ligation.
Materials and Methods: Carpentier-Edwards perimount, pericardial bioprostheses were implanted
in 168 consecutive patients between January 2000 and March 2017 in the mitral position due to
rheumatic heart disease. The patient’s ages ranged between 12 and 75 years (mean ± SD 34.2 ± 9.8
years). Sixty-eight (40.4%) patients had giant left atrium measuring more than 65 mm diameter.
Sixty (35.7%) patients underwent surgical reduction of giant left atrium. The left atrial appendage
was ligated in 110 (65.5%) patients.
Results: The hospital and late mortalities were 1.8% and 1.8% respectively. The total cumulative
follow-up period was 1447.2 patient-years with a mean of 107.2 ± 56.4 months (range, 1-207
months). There were 7 events of thromboembolism (2 events per 100 patient-years) and two
instances of left atrial clot requiring re-institution of warfarin therapy. The actuarial survival and
actuarial event-free survival at 207 months was 95.04% (± 0.02%) and 88.1% (± 0.04%) respectively.
Conclusion: We conclude that anticoagulation may be discontinued after 3 months in the majority
of patients undergoing bioprosthetic MVR. Low intensity anticoagulation with an INR between 1.5
and 2.0 should be continued lifelong in a select subset of patients with preoperative atrial fibrillation,
thromboembolism, giant left atrium, and low left ventricular ejection fraction and bioprosthetic
degeneration. Liberal left atrial appendage ligation and surgical reduction of giant left atrium during
MVR is consistent with reduction of surgical mortality, low cardiac output syndrome, respiratory
complications and risk of late systemic embolism.
Keywords: Mitral valve replacement; Carpentier-edwards pericardial prosthesis; Bioprosthetic degeneration; Thromboembolism; Left atrial appendage
Introduction
The ideal prosthetic valve should have excellent hemodynamics (similar to a normal human
valve in the same position), last a lifetime, be free of structural dysfunction or deterioration, and
require no anticoagulation. Needless to say, such a valve is yet to be available [1].
Mechanical valves have a high incidence of thromboembolism. They also require life-long
anticoagulation which disposes the patient to complication of anticoagulation related hemorrhage.
For St Jude Medical mechanical prosthesis, the reported actuarial survival rate is 61.3 ± 3.3% at
19 years. Bleeding complications related to anticoagulation was 1% per patient-year. The valve
thrombosis rate is 0.2% per patient year. The percentages of patients free of endocarditis and valve
avulsion are 98.6 ± 1% and 90 ± 3%, respectively [2,3].
In our previous publications, we demonstrated similar problems
of valve thrombosis, anticoagulation related hemorrhage and
thromboembolic complications following mechanical Mitral Valve
Replacement (MVR) using a St. Jude mechanical prosthesis (St. Jude
Medical Inc., St. Paul, MN) [4,5].
Several investigators including ourselves have noted that 20%
patients had persistently poorly controlled anticoagulation during
a follow-up of 10 years [4-7]. This clearly reflects the difficulty in
the practical management of this treatment, the constraints that
anticoagulants can impose on these patients, and the possible
alteration of their quality of life. The problem of anticoagulation and
the complications induced by anticoagulation account for 80% of
valve-related complications [5-7].
Thromboembolism is perhaps the most common complication of
both biologic and mechanical mitral prostheses but is more frequent
in patients with mechanical valves. Bioprosthetic valves have a lower
incidence of thromboembolism even in absence of anticoagulation
[1-9].
Thromboembolism in patients with MVR is lower in those with a
small left atrium, sinus rhythm, and normal cardiac output. It is much
higher in patients with large left atrium, chronic atrial fibrillation, and
the presence of intra-atrial clot [6-8]. ACC/AHA Practice Guidelines
recommend anticoagulation for life in patients with atrial fibrillation
[11]. Left atrial appendage ligation has been shown to reduce the
incidence of cardiovascular accident in high risk patients with
prosthetic heart valves [12-16].
The aim of the present study is to evaluate the incidence
thromboembolism in patients implanted with tissue mitral valves and
to evaluate risk and benefits of left atrial appendage ligation.
Figure 1
Figure 1
Bar graph showing the age distribution of patients undergoing
bioprosthetic mitral valve replacement in the study group.
Patients and Methods
Between January 2000 and March 2017, a total of 168 consecutive
patients (69 males) with rheumatic heart disease undergoing
bioprosthetic mitral valve replacement using Perimount pericardial
bioprosthesis model 6,900-mitral (Edwards Life Sciences, Baxter
Health Care Corporation, Irvine, CA, USA) at All India Institute of
Medical Sciences, New Delhi, India, operated by the corresponding
author (UKC) were included in the study. Selection of the porcine
Carpentier-Edwards prosthesis was determined by patients’
preference and surgeon judgement.
The indications for use of bioprosthesis in these patients were:
1. Patients coming from remote rural areas where routine
follow-up and anticoagulation monitoring is practically difficult,
2. Contraindications to the use of anticoagulation,
3. Young females desirous of pregnancy,
4. Patients undergoing redo mitral valve surgery due to
previous mechanical valve dysfunction/thrombosis, and
5. Patient’s choice because of lifestyle considerations.
Institutional review board approval for this study protocol was
available and informed consent was obtained from all patients. Our
institutional policy is to use tissue valves only after the bone growth
and maturation completed that is after 18 years of age. There were two
patients below 18 years of age. One patient, aged 12 years with prior
mechanical valve replacement had prosthetic valve dysfunction due
to thrombosed mitral prosthesis; hence the valve had to be replaced
with a tissue valve. Other patient aged 13 years had thalassemia with
hemolysis and a tissue valve was chosen over mechanical valve.
The mean age of the patients was 34.2 ± 9.8 years (range 12-75
years). The age distribution is depicted in Figure 1. One hundred and
thirty-seven (81.5%) patients were in NYHA class III and 31 (18.5%)
patients were in NYHA class IV. Thirty (17.8%) patients were on
inotropic support and 10 (5.9%) patients were on ventilator in the
preoperative period. Preoperatively, 5 (2.9%) patients required intraaortic
balloon counterpulsation for stabilization of hemodynamics.
Ninety-seven (57.7%) patients had predominantly mitral stenosis
(indexed mitral valve area < 1 cm2/m2) and 64 (38.1%) patients had
mixed mitral valve disease. Seven (4.2%) patients underwent redo
mitral valve replacement due to thrombosed prosthetic mitral valve.
Fifteen (8.9%) patients had undergone closed mitral valvotomy and 8
(4.8%) patients had previous balloon mitral valvotomy. Eight (4.8%)
patients had previous mitral valve repair, 31 (18.5%) patients had clot
within the left atrium/left atrial appendage and 8 (4.8%) patients had
history of preoperative thromboembolism. One hundred and thirteen
(67.3%) patients in the study group were in atrial fibrillation in the
preoperative period and 96 (57.1%) patients continued to remain
in atrial fibrillation in the postoperative period. Preoperatively, 68
(40.4%) patients had giant left atrium more than 65 mm in diameter
and 41 (24.4%) patients had left ventricular ejection fraction between
15% to 25% (Table 1).
Surgery was performed through a median sternotomy (n=163) or
right anterolateral thoracotomy (n=5) with standard normothermic
or moderately hypothermic cardiopulmonary bypass. Antegrade
cold blood cardioplegic solution and topical cooling were used for
myocardial protection in all patients. A trans-septal approach (n=54)
was used in patients with a small left atrium and in cases of associated
tricuspid valve or atrial septal defect. All efforts were made to preserve
the chordo-papillary apparatus without causing prosthetic valve
entrapment or left ventricular outflow obstruction. Total chordopapillary
apparatus was preserved using Miki’s technique whenever
feasible (n=45, 26.8%) [17]. In patients with calcified leaflets with
annular extension and severe subvalvular fusion, the mitral apparatus
was completely excised [n=14 (8.3%)]. The remaining patients
had only posterior chordal preservation [n=109 (64.8%)]. The
technical details of chordal preservation, annulus decalcification and
reconstruction had been addressed in our earlier publications (Table
2) [4,5].
Mitral valve replacement was performed using Perimount
pericardial bioprosthesis model 6,900 -mitral (Edwards's life sciences,
Irvine, CA, US). Size of bioprosthetic valve ranged from 25 mm to 33
mm (median 27). Intra-operative trans-esophageal echocardiography
was performed to confirm satisfactory prosthetic valve function
immediately after surgery.
Patients (n=17) undergoing redo MVR for dysfunctional
mechanical prosthetic valve (n=7) and degenerated bioprostheses
(n=10) were subjected to a uniform surgical protocol standardized
by the corresponding author. The redo operations were performed
under moderately hypothermic cardiopulmonary bypass through
femoral arterial cannulation (Medtronic Bio-Medicus Percutaneous
Arterial Femoral, Medtronic Inc., Minneapolis, MN, USA) and
bicaval venous cannulation through the femoral vein (Medtronic
Bio-Medicus Percutaneous Venous Femoral) and superior vena cava.
Redo sternotomy was performed under cardiopulmonary bypass
in all these patients (n=17). Antegrade cold blood hyperkalemic
cardioplegia was used in all patients for myocardial preservation.
A mechanical heart valve [(Medtronic Open PivotTM AP360° Apex
and AP, Medtronic Inc., Mx, USA); size 24 mm, 5 patients; 26 mm,
5 patients] was used in patients undergoing explantation of the
degenerated bioprosthesis. Two patients undergoing redo MVR
required left atrial thrombectomy in addition. Sixty-eight (40.4%)
patients had left atrial size more than 65 mm. Sixty (35.7%) patients
underwent surgical reduction of the giant left atrium. The left atrial
appendage was ligated in 110 (65.5%) patients. No surgical procedure
was performed for atrial fibrillation (Table 2).
Following MVR with or without chortal preservation, the disc
movements were checked and left atrial volume reduction was done in
patients with giant left atrium by a combination of para-annular and
superior plication techniques. The postero-inferior wall of left atrium
between the ostia of inferior pulmonary veins and mitral annulus was
plicated in a semi-lunar fashion using interrupted 3-0 polypropylene
mattress sutures over polytetrafluoroethylene pledgets.
The successive sutures were placed at a distance of 20 mm to 30
mm from each other, 15 mm to 20 mm from the pulmonary venous
ostia and 10 mm from the annulus. The superior plication was done
in the area between the right and left pulmonary veins. While closing
the left atriotomy, the redundant left atrial wall above the right
pulmonary veins was plicated in two layers using 3-0 polypropylene
sutures. Subsequently, the base of the enlarged left atrial appendage
was doubly ligated externally using no.3 (SUTUPAK) braided black
silk (Johnson & Johnson Ltd) sutures.
The mean left ventricular ejection fraction was 55 ± 6.8% (range,
15% to 70%). Forty-one (24.4%) patients had left ventricular ejection
fraction between 15% to 25%. Mean cardiopulmonary bypass time
was 63.3 ± 19.8 min (range 38 to 182 min) and aortic cross-clamp
time was 38 ± 17.6 min (range 27 to 131 min).
Patients were started on warfarin on first postoperative day
maintaining an International Normalized Ratio (INR) between
2.0-2.5. After discharge, these patients were reviewed at one week,
one month, 3 months, then subsequently at 6 months intervals.
International normalized ratio was tested till 12 weeks after which
anticoagulation was stopped. Warfarin therapy was re-instituted
if there was a thromboembolic event or there was a newly formed
clot within the left atrium or left atrial appendage, in patients with
persistent atrial fibrillation, bioprosthetic degeneration with stiffened
leaflets and increased transprosthetic gradients maintaining an INR
between 1.5 and 2.0. All patients received Asprin life long, unless
contraindicated.
Transthoracic two-dimensional (2D), color flow and Doppler
echocardiography was performed using a Hewlett-Packard-
Sonos-5500 with 2.7 or 3.5 MHz transducer. Prosthetic valve function
was assessed on M-mode parasternal long-axis view and 2D apical
four-chamber view. Left ventricular outflow tract obstruction was
assessed on an apical five-chamber view, and by Doppler study. A
Doppler velocity of greater than 2 m/s was considered significant
for LVOTO. Echocardiographic data were measured according to
American Society of Echocardiography criteria [18]. The ventricular
and prosthetic valvular function was assessed within first six months
then annually.
Follow-up data included clinical history and assessment of NYHA
class, occurrence of events such as thromboembolism, hemorrhage,
infective endocarditis, congestive heart failure etc. Electrocardiogram
was done at each review to assess the heart rhythm and screen for new
onset of atrial fibrillation. A valve-related event was defined as any
episode of thromboembolism, hemorrhage, congestive heart failure,
infective endocarditis, structural deterioration, significant gradients
or bioprosthetic valve dysfunction as per the published criteria [19].
Statistical analysis
Statistical analysis was performed using Intercooled STATA 9.0
software (College Station, Texas, USA). All variables were defined
in compliance with the guidelines established by The American
Association for Thoracic Surgery and the Society of Thoracic Surgeons
[11]. Variables analyzed included valvular thromboembolism
(including episodes of embolism, transient ischemic attacks, and
valve thrombosis), anticoagulation-related hemorrhage (defined
as episodes resulting in death, stroke, surgery, hospitalization, or
transfusion), prosthetic heart valve thrombosis and valve-related
mortality.
Interval related data were expressed as mean ± Standard Deviation
(SD) and categorical variables were expressed as percentages.
Mortality rates were calculated depending on the total number of
years of follow-up. Freedom from valve related events and event
free survival have been calculated using the Kaplan-Meier analysis.
Statistical significance was set at p<0.05.
Figure 2
Figure 2
Actuarial survival curve (Kaplan-Meier) of patients undergoing mitral
valve replacement using a Carpentier-Edwards Perimount Bioprosthesis in
the study group.
Figure 3
Figure 3
Actuarial event free (Kaplan-Meier) survival of patients
undergoing mitral valve replacement using a Carpentier-Edwards Perimount
Bioprosthesis in the study group.
Table 1
Table 1
Demographic details of patients undergoing mitral valve replacement
using Carpentier-Edwards pericardial bioprosthesis (n=168).
Table 2
Results
There were 3 (1.8%) early deaths. Two patients died due to low
output syndrome. Both deaths occurred in patients who were in
congestive cardiac failure preoperatively and underwent redo MVR
for mechanical prosthetic valve dysfunction. One patient died in the
immediate postoperative period secondary to acute biventricular
dysfunction. Patients considered to have low cardiac output syndrome
(n=79) required dopamine (4-10 μg.kg-1.min-1), epinephrine (0.01-
0.1 μg.kg-1.min-1) and milrinone (50 μg/kg IV bolus followed by
0.375-0.75 μg.kg-1.min-1) either isolated or in combination. Ten
(5.9%) patients required intraoartic balloon counterpulsation as an
additional support. Hospital morbidity included re-exploration for
excessive bleeding within 12 hr in 6 patients. Four patients required
tracheostomy and long-term ventilatory support. Three patients
required hospital admission of 18th, 20th and 21st postoperative days
because of deranged prothrombin time requiring pericardiocentesis.
All patients with normal renal function were administered oral
angiotensin enzyme inhibitor (ACE) (0.5-1.0 mg/kg; every 8 hr)
after extubation before weaning from inotropic agents. Digoxin,
diuretics and ACE inhibitors were weaned at varying time intervals.
Amiodarone was used for intractable atrial fibrillation. Hospital stay
ranged from 5 to 52 days (median 8.8) Mean hospital stay was 8.8 ±
5 days.
Late Outcomes
There were three (1.8%) late deaths 45 days, 3 months and 9
months after surgery due to persistent left ventricular failure (n=2)
and intractable ventricular arrhythmias (n=1). Out of 113 patients
who were in atrial fibrillation in the preoperative period, 96 (84.9%)
patients remained in atrial fibrillation and 17 (15%) reverted to sinus
rhythm. No new onset atrial fibrillation was reported in any survivors
of this study.
One hundred and sixty-two survivors (96.4%) were followed up
in outpatient department. Follow up was 100% complete and yielded
1447.2 patient-years data with a mean follow up time of 107.2 ± 56.4
months (range, 1 to 207 months). The actuarial survival at a mean
follow-up of 107.2 ± 56.4 months was 95.04 ± 0.02% (95% CI: 89.01-
97.8) (Figure 2). The actuarial event free survival at 107.2 ± 56.4
months was 88.1 ± 0.04% (95% CI: 78.9-93.5) (Figure 3).
There were 7 events of thromboembolism (transient ischemic
attacks, n=5; reversible hemiparesis, n=1; femoral thromboembolism,
n=1). Preoperatively, these patients (n=7) were in atrial fibrillation with
a left atrial size < 40 mm and without any clot within the left atrium/
left atrial appendage. They were without any oral anticoagulation and
were on ecospirin alone. These patients were treated conservatively
and recovered uneventfully. None of these patients required any
surgical intervention. Echocardiographic evaluation in these patients
demonstrated normal left ventricular function and there was no clot
in any cardiac chambers. Details of patient profile who had episodes
of thromboembolism are depicted in Table 3. In all patients, warfarin
was restarted to maintain International Normalized Ration (INR) of
1.5 to 2.0. There was no recurrence of thromboembolic event or valve
thrombosis. The left atrial appendage was not ligated in any patients.
Ten patients aged 43, 39, 50, 55, 36, 50, 52, 59, 60 and 65 years
respectively developed severe bioprosthetic degeneration with
predominant stenosis between 7 and 11 years (mean ± SD, 107.18
± 56.4 months) after primary tissue valve replacement (Figure
3). Intraoperatively, two-dimensional and three-dimensional
transesophageal echocardiography demonstrated severe prosthetic
valve stenosis and no regurgitation. They underwent redo MVR
using a Medtronic mechanical prosthesis and removal of the left
atrial thrombus (n=2) as stated above. These two patients with left
atrial clot had unligated left atrial appendage with atrial fibrillation
and was not on oral anticoagulation. Examination of the explanted
bioprostheses revealed severely restricted mobility due to stiffening
and calcification of the leaflets. Postoperatively, one patient
undergoing redo bioprosthetic replacement required intra-aortic
balloon counterpulsation in addition to inotropes for low cardiac
output syndrome. Two patients undergoing redo-MVR due to
degenerated bioprostheses had large left atrial clot. These two patients
were without anticoagulation, in atrial fibrillation, had unligated left
atrial appendage and calcific, stifeened, stenosed bioprostheses with
excess transprosthetic gradients. These patients (n=10) survived
the reoperation and are presently in NYHA class I. There were no
structural failure among the remaining survivors (n=152) over the
follow-up period.
Echocardiographically obtained hemodynamic measurements
are detailed in Table 4. Valve leaflet thickening with mild prosthetic
valve stenosis was seen in two patients at 32 and 40 months of followup.
Table 3
Table 4
Table 4
Details of postoperative echocardiographic gradients (at one week) across the prosthetic valve in patients undergoing mitral valve replacement using a
bioprostheis.
Discussion
The procedure of choice for mitral valve disease is mitral valvular
reconstruction wherever feasible [1-20]. For patients requiring MVR,
the ideal valve is not yet available and surgeons need to choose between
mechanical prostheses with the risk of anticoagulation-related
hemorrhage and biologic valves with the risk of deterioration and
reoperation [1-20]. Following bioprosthetic heart valve implantation,
structural deterioration and the need for reoperation appear higher
in mitral than in the aortic position, and many studies recommend its
use in patients of older age [21-26].
Pericardial bioprostheses have been clinically used in human
beings since 1970. The first generation of this type of valve has been
withdrawn from the market because of its poor clinical results [23-
26]. The cause of deterioration was due to faulty design and tissue
preparation failure [21,23-26].
The Carpentier-Edwards pericardial valve was designed with an
original leaflet clamping technique which eliminates the retention
suture and also abrasion risk [23,24-26]. Pericardium is carefully
procured and treated with glutaraldehyde. With these characteristics,
this pericardial bioprosthesis showed satisfactory intermediate results
in both aortic and mitral positions, reestablishing pericardium as a
good valve substitute [3,25,26]. These results especially in the mitral
position, promise an interesting long-term follow-up.
Use of bioprosthetic valves confers an advantage over
mechanical valve as no anticoagulation is required. Continuing with
anticoagulation exposes the patient to increased risk of haemorrage
whereas discontinuing the anticoagulation therapy may result in
a higher incidence of thromboembolism. However, the duration
of anticoagulation therapy following valve replacement with a bioprosthesis
remains controversial [6,7,9,16].
Due to increased risk of bleeding with anticoagulant therapy and
the inability of appropriate prothrombin measurements indefinitely
after operation, we decided to stop anticoagulation at 12 weeks and
continue only with aspirin at a dose of 150 mg/day. This policy was
continued even in patients who are in atrial fibrillation, had left atrial/
left atrial appendage clot or preoperative history of thromboembolic
episode. With this strategy, we observed comparable low rate of
thromboembolism of 2 events per 100 patient years. Our actuarial
event free survival at 207 months was 88.1% ± 0.04% (95% CI: 78.8-
93.5) which is comparable to those reported by Akins and Jamieson
[16,18]. Ruel and colleagues also showed that tissue heart valves
have lesser incidence of anticoagulation related hemorrhage with
no difference in actuarial survival, thromboembolism, infective
endocarditis, paravalvular leak, structural deterioration and valve
related dysfunction [15].
Ligation of the left atrial appendage during mitral valve surgery
is still controversial [11,16]. Left atrial appendage is routinely ligated
in patients undergoing closed mitral valvotomy for rheumatic mitral
stenosis in an attempt to reduce the risk of thromboembolism [28].
Several investigators have shown that Left Atrial Appendage (LAA)
ligation during surgery of MVR, performed in a high-risk population
is consistent with a reduction of the risk of late systemic embolism.
Several other studies have confirmed that the LAA plays a very
important role in the formation of LA thrombus in patients with
atrial fibrillation. In patients with rheumatic and non-rheumatic
AF, at least 60% and 90% of LA thrombi, respectively, are located in
the LAA. Therefore, it is likely that ligation of the LAA in patients
undergoing cardiac surgery may greatly reduce the risk of stroke [11-
16]. The utilization of this technique depends on the methodology and
insight of the different surgical teams despite that it is a recommended
procedure in the ACC guidelines [10].
Orszulak and colleagues evaluated the risk of stroke in elderly
patients during the early postoperative period after MVR with
a Carpentier-Edwards biological prosthesis and found a strong
correlation between late stroke and left atrial appendage in patients
undergoing MVR and CABG [29]. However, in the group of patients
with isolated MVR and in the overall group, the only independent
variable associated with a greater risk of late stroke was an advanced
NYHA class [29].
Juratli and colleagues analyzed the effectiveness of LAA ligation
during mitral valve surgery (50% underwent mitral valve repair
and 23% received a mechanical prosthesis) as an alternative to
anticoagulant treatment with warfarin [13]. Left atrial appendage
ligation did not provide an adequate protection from thromboembolic
events in the absence of effective anticoagulation treatment with
warfarin [13].
In our study population, 67.3% (n=113) were in atrial fibrillation,
40.4% (n=68) had left atrial size >65 mm, 18.5% (n=31) were having
left atrial appendage/left atrial clot, 4.8% (n=8) had preoperative
history of thromboembolism, and 24.4% (n=41) patients had left
ventricular ejection fraction < 0.25. Two patients undergoing redo-
MVR due to degenerated bioprostheses had large left atrial clot
within the left atrium. These two patients were in atrial fibrillation,
without oral anticoagulation, had unligated left atrial appendage and
calcific stiffened, stenosed bioprostheses with excess transprosthetic
gradients. Left atrial appendage ligation was done in 65.5% (n=110)
patients, surgical reduction of left atrium was done in 35.7% (n=60)
of patients with giant left atrium. Twenty-three (13.7%) patients had
amputated left atrial appendage during previous surgery and in 58
(34.5%) patients, left atrial appendage was not ligated due to small
size.
Currently, there is no consensus regarding the management of
giant left atrium during mitral valve surgery. Most surgeons fix the
mitral valve and do little to an oversized left atrium. Others occlude
the left atrial appendage [30,31]. The co-existence of giant left atrium
associated with mitral valve disease has been reported as a significant
risk factor in mitral valve surgery with surgical mortality ranging from
8% to 23% [30,31]. Currently, high mortality rates following mitral
valve surgery above 5% are not acceptable with improved operative
techniques, modern anaesthetics and postoperative care.
In this study, 40.4% (n=68) patients had giant left atrium and
60 of 68 patients underwent left atrial volume reduction with three
objectives: i) reduction of hospital mortality, ii) elimination of
symptoms and alleviating the pressure effect to the left ventricle,
bronchus and lung parenchyma, and iii) reduction of early
postoperative complications related to low cardiac output syndrome
and respiratory complications.
Importantly, significant reduction of hospital and late mortalities
of 1.8% and other two above mentioned objectives were achieved
by employing this strategy of surgical reduction of left atrial size in
patients with giant left atrium and chordal preservation whenever
feasible during MVR. We performed the simplest modality for size
reduction by plicating the inferior and superior LA wall and ligating
the base of the left atrial appendage. We avoided partial excision
of the superior wall of left atrium because it carries greater risk for
bleeding and atrioventricular node blockade.
A significant proportion of the study population was at high risk for
thromboembolism. In our study, the incidence of thromboembolism
was 2 per 100 patient years which is comparable to published results
by other investigators [3,12]. In this study, using the anticoagulation
management protocol as stated above, the incidence of postoperative
thromboembolism was higher in females, those with atrial fibrillation,
LA clot and preoperative history of thromboembolism and poor left
ventricular function. Due to the occurrence of thromboembolic events
in these high risk subset of patients as above and those presenting
with bioprosthetic degeneration with high transprosthetic gradients,
we restarted low intensity anticoagulation in these high risk subset of
patients maintaining an INR between 1.5 and 2.0.
Our data further suggests that the surgical LAA ligation and left
atrial size reduction together with MVR reduces the incidence of low
cardiac output syndrome and late strokes. Our data provides new
information about potential impact of LAA ligation and surgical
reduction of giant left atrium until new data of a randomized study
with blinded event verification are available.
Study Limitations
Like that of other observational cohorts, the results of this study may not be generalizable globally to all patients undergoing bioprosthetic MVR with longer follow-up, the incidence of thromboembolism may raise further.
Conclusion
Our study shows that liberal LAA ligation and surgical reduction of giant left atrium during MVR is consistent with reduction of surgical mortality, low cardiac output syndrome, respiratory complications, risks of late embolism and supports this strategy if a MVR is indicated. Because of an increase in risk of thromboemboli in the first three months after implantation of a biological prosthetic valve, anticoagulation with warfarin is usually recommended. After 3 months, biological valve can be treated like native valve disease and Warfarin can be discontinued in over two-thirds of patients with biological valves. In the remaining patients with associated risk factors for thromboembolism, such as aneurysmal left atrium with atrial fibrillation, previous thromboembolism, poor left ventricular function, and bioprosthetic degeneration, life-long low dose warfarin therapy is indicated to achieve an INR of 1.5 to 2.0.
References
- Remadi JP, Baron O, Roussel C, Bizouarn P, Habasch AI, Despins P, et al. Isolated mitral valve replacement with St Jude medical prosthesis, long-term results: A follow-up of 19 years. Circulation. 2001;103(11):1542-5.
- Jamieson SW, Madani MM. The choice of valve prostheses. J Am Coll Cardiol. 2004;44(2):389-90
- Khan SS, Trento A, DeRobertis M, Kass RM, Sandhu M, Czer LS, et al. Twenty-year comparison of tissue and mechanical valve replacement. J Thorac Cardiovasc Surg. 2001;122(2):257-69.
- Chowdhury UK, Kumar AS, Airan B, Mittal D, Subramaniam KG, Prakash R, et al. Mitral valve replacement with and without chordal preservation in a rheumatic population: serial echocardiographic assessment of left ventricular size and function. Ann Thorac Surg. 2005;79(6):1926-33.
- Chowdhury UK, Venkataiya JKH, Patel CD, Seth S, Yadav R, Singh R, et al. Serial radionuclide angiographic assessment of left ventricular ejection fraction and regional wall motion after mitral valve replacement in patients with rheumatic disease. Am Heart J. 2006;152(6):1201-7.
- Cohn LH, Sanders JH, Collins JJ Jr. Actuarial comparison of Hancock porcine and prosthetic disc valves for isolated mitral valve replacement. Circulation. 1976;54(6): III60-3.
- Rahimtoola SH. Choice of prosthetic heart valve for adult patients J Am Coll Cardiol 2003;41(6):893-904.
- John S, Ravikumar E, Jairaj PS, Chowdhury UK, Krishnaswami S. Valve replacement in the young patient with rheumatic heart disease: Review of a twenty-year experience. J Thorac Cardiovasc Surg. 1990;99(4):631-8.
- Aupart MR, Neville PH, Hammami S, Sirinelli AL, Meurisse YA, Marchand MA. Carpentier-Edwards pericardial valves in the mitral position: ten-year follow-up. J Thorac Cardiovasc Surg. 1997;113(3):492-8.
- Blackshear JL, Odell JA. Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation. Ann Thorac Surg. 1996;61(2):755-9.
- Bonow RO, Carabello B, de Leon AC, Edmunds LH, Fedderly BJ, Michael D, et al. ACC/AHA Guidelines for the management of patients with valvular heart disease: Executive summary: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee of Management of Patients with Valvular Heart Disease). J Heart Valve Dis. 1998;7(6):672-707.
- Hannon N, Sheehan O, Kelly L, Marname M, Marwick A, Moore A, et al. Stroke associated with atrial fibrillation: Incidence and early outcomes in the North Dublin population stroke study. Cerebrovasc Dis. 2009;29(1):43-9.
- Johnson WD, Ganjoo AK, Stone CD, Srivyas RC, Howard M. The left atrial appendage: our most lethal human attachment! Surgical implications. Eur J Cardiothorac Surg. 2000;17(6):718-22.
- Juratli N, Wilkoff B, Tchou P, Cosgrove DM, Lytle BW, Chung MK, et al. Left atrial appendage ligation during mitral valve surgery may increase the risk of late thromboembolic event. J Am Coll Cardiol. 2002;39:85A.
- Al Saady NM, Obel OA, Camm AJ. Left atrial appendage: structure, function, and role in thromboembolism. Heart. 1999;82(5):547-54.
- Di Sesa VJ, Tam S, Cohn LH. Ligation of the left atrial appendage using an automatic surgical stapler. Ann Thorac Surg. 1988;46(6):652-3.
- Miki S, Kusuhara K, Ueda Y, Komeda M, Ohkita Y, Tahata T. Mitral valve replacement with preservation of chordae tendineae and papillary muscles. Ann Thorac Surg. 1988;45(1):28-34.
- Cheitlin MD, Armstrong WF, Aurigemma GP, Beller GA, Bierman FZ, Davis JL, et al. Guideline update for the clinical application of echocardiography: Summary article. J Am Soc Echocardiogr. 2003;16(10):1091-110.
- Guidelines for reporting morbidity and mortality after cardiac valvular operations. Ann Thorac Surg. 1988;46(3):257-9.
- Bloomfield P, Wheatley DJ, Prescott RJ, Miller HC. Twelve year comparison of a Bjork- Shiley mechanical valve with porcine bioprosthesis. N Engl J Med. 1991;324(9):573-9.
- Bortolotti U, Milano A, Guerra F, Mazzucco A, Mossuto E, Thiene G, et al. Failure of Hancock pericardial xenografts: Is prophylactic bioprosthetic replacement justified? Ann Thorac Surg. 1991;51(3):430-7.
- Deloche A, Jebara VA, Relland JY, Chauvaud S, Fabiani JN, Perier P, et al. Valve repair with Carpentier techniques: the second decade. J Thorac Cardiovasc Surg 1990;99(6):990-1002.
- Gallo I, Nistal F, Revuelta JM, Garcia-Statue E, Artinano E, Duran CG. Incidence of primary valve failure with the Ionescu-Shiley pericardial valve. J Thorac Cardiovasc Surg. 1985;90(2):278-80.
- Leandri J, Bertrand P, Mazzucotelli JP, Loisance D. Mode of failure of the Mitroflow pericardial valve. J Heart Valve Dis 1992;1(2):225-31.
- Walley VM, Rubens FD, Campagna M, Pipe AL, Keon WJ. Patterns of failure in Hancock pericardial bioprostheses. J Thorac Cardiovasc Surg 1991;102(2):187-94.
- Aupart M, Neville P, Dreyfus X, Meurisse Y, Sirinelli A, Marchand M. The Carpentier Edwards pericardial aortic valve: intermediate results in 420 patients. Eur J Cardio Thorac Surg 1994;8(5):277-80.
- Akins CW, Carroll DL, Buckley MJ, Daggett WM, Hilgenberg AD, Austen WG, et al. Late results with Carpentier-Edwards porcine bioprosthesis. Circulation 1990;82(4):65-73.
- John S, Bashi VV, Jairaj PS, Muralidharan S, Ravikumar E, Rajarajeswari T, et al. Close mitral valvotomy: Early results and long-term follow up of 3724 consecutive patients. Circulation. 1983;68(5):891-6.
- Orszulak TA, Schaff HV, Pluth JR, Danielson GK, Puga FJ, Ilstrup DM, et al. The risk of stroke in the early postoperative period following mitral valve replacement. Eur J Cardiothorac Surg. 1995;9(11):615-9.
- Kawazoe K, Beppu S, Takahara Y, Nakajima N, Tanaka K, Ichihashi K, et al. Surgical treatment of giant left atrium combined with mitral valvular disease. Plication procedure for reduction of compression to the left ventricle, bronchus and pulmonary parenchyma. J Thorac Cardiovasc Surg. 1983;85(6):885-92.
- Piccoli GP, Massini C, Di Eusanio G, Ballerini L, Iacobone G, Soro A, et al. Giant left atrium and mitral valve disease: early and late results of surgical treatment in 40 cases. J Cardiovasc Surg (Torino). 1984;25:328-36.