Abstract
Objectives: To describe the results of transcatheter aortic valve
implantation in high-risk patients with aortic stenosis using the transapical
approach.
Methods: From September 2006 till March 2010, with the mean
follow up of 2 years, forty-five patients with severe symptomatic aortic
stenosis were treated with transapical - transcatheter aortic valve
implantation using the Edwards SAPIEN valve, because of high surgical risk or contraindications
to surgery. Mean age was 81±10 years, mostly in New York Heart Association classes III/IV, the predicted surgical mortality was (12±16%) using
the European System for Cardiac Risk Evaluation (EuroSCORE); or the Society of
Thoracic Surgeons Predicted Risk Of Mortality (STS-PROM) more than 10%.
Results: Successful implantation was achieved in all patients
with satisfactory postoperative gradients. In-hospital mortality was 18%. Stroke was not observed in any patient.
Conclusions: Transcatheter aortic valve implantation provides a
privileged and direct approach to the aortic valve and allows antegrade
manipulation of the instruments. There are no limits on the size of introducing
system and it is not affected by peripheral vessel tortuosity or disease.
Key words: Aortic valve replacement, Calcific aortic valve stenosis,
Transcatheter aortic valve
implantation, Transapical
JRMS
December 2011; 18(4): 5-9
Introduction
Aortic
Stenosis (AS) is the most common valvular pathology in western countries(1)
with a prevalence that is expected to markedly increase as the population ages.
The onset of symptoms heralds a mortality rate of about 25% per year and the
mortality rate at 5 and 10 years is 68% and 82% respectively.(2)
Aortic Valve Replacement (AVR) is indicated in severe
symptomatic AS.(3) Conventional
surgical AVR performed
under cardiopulmonary bypass and aortic cross-clamping is the reference
treatment and has shown to improve outcome and survival. When performed as an
isolated procedure, it carries an average 30 day mortality of 3.8±1.5%.(4)
However, certain factors are known to increase the operative risk. A
large multivariate study, showed that the 5 most important predictors of
mortality after AVR were age≥80 years, New
York Heart Association (NYHA) class ≥III, Ejection Fraction
(EF)≤30% associated with previous MI, emergent AVR and concomitant Coronary Artery Bypass Grafting (CABG) surgery.(4) Patients with severe AS can thus
be refused surgery in the presence of severe comorbidities; this was the case in 31.8% of
patients in the Euro Heart Survey on Valvular Heart Disease(1)
and 62% of patients in a similar study from the USA.(2) With the aging population, the
proportion of patients with contraindications for surgery is also expected to
increase.
In
addition to comorbidities, patients may present with technical difficulties
and complexities which make AVR challenging to perform. This is particularly
true in patients undergoing redo surgery with patent coronary artery bypass
grafts, those with previous mediastinal radiotherapy or in the presence of a
heavily calcified and atheromatous ascending aorta (porcelain aorta).(5)
Transcatheter
Aortic Valve Implantation (TAVI) techniques have been developed to provide
alternative approaches to patients who fall into these categories and for whom
conventional AVR is associated with very high risk. These techniques do not
require cardiopulmonary bypass or aortic cross clamping and can be performed
under general or locoregional anesthesia, with fluoroscopic and
echocardiographic guidance.(6) These techniques have been
performed via two different approaches, the Transfemoral (TF) and Transapical
(TA) routes with established feasibility.(7)
In this
study, we describe the results of transcatheter aortic valve implantation in
high-risk patients with aortic stenosis using the transapical approach.
Methods
From
September 2006 to March 2010, with mean follow up of 2 years, 45 patients with
severe symptomatic AS requiring AVR, with mean pressure gradient of 50±12 mmHg,
Aortic Valve Area (AVA) of 0.72±0.17 2cm, and Left Ventricular Ejection
Fraction (LVEF) of 49±13%, in whom conventional surgery was considered high
risk or contraindicated by a multidisciplinary team or for whom the TF route
could not be performed,
which were mainly unsuitable femoroiliac accesses and severely
calcified aortic arch and descending aorta, were
referred for TAVI via the transapical approach and included in a prospective
registry. Demographic and patients’
characteristics are described in Table I. Ethical committee approval was obtained and
all patients gave informed consent and underwent complete evaluation using Transthoracic
Echocardiography (TTE), coronary angiography, aortic and femoroiliac angiography. The procedure was performed under general
anaesthesia, the patient heparinised (75 IU/kg b.w., IV). Heparin was reversed at the end of the procedure.
In all patients, the implanted valve was the Edwards SAPIEN Transcatheter Heart
Valve (Edwards Lifesciences Inc., CA, USA). TAVI was performed through a
left antero-lateral mini-thoracotomy. The site of the incision was determined
by localisation of the apex by TEE prior to prepping the patient. The pericardium
was opened and attached to the chest wall. The left ventricular apex was then
punctured through 2 purse-string sutures. A sheath (initially 33 French, then
26 French) was introduced in the left ventricle and the prosthesis implanted
using the antegrade route via the AscendraTM system under rapid
ventricular pacing.(8)
Implantation
success was defined by valve implantation in the correct position. Outcomes were described according to the
guidelines for reporting mortality and morbidity after cardiac interventions.(9)
Procedural success is defined as valve implantation in the correct position,
with good immediate hemodynamic result and no major complications.
Results
Procedural
success for TAVI was 100%. There was no intraoperative mortality. In all, the
aortic valve area and mean trans-prosthetic gradient were satisfactory. There
were no prosthesis malpositioning or conversion to on-pump surgical AVR.
Paravalvular leaks were frequent immediately after implantation, but were mild
or moderate in 14/45 patients (31%). In
one patient, immediate post-implantation severe aortic regurgitation was
managed by implantation of a second prosthesis into the first one (“valve
after valve”) with satisfactory results as shown in (Table II).
Vascular
complications occurred in 6/45 patients (12%). One patient had delayed rupture
(after one week) of the femoral arterial access site, and one patient with
severe peripheral artery disease had thrombosis of the common iliac artery in
the context of septic shock, leading to leg ischemia and contributing to her
eventual demise, the other 4 patients had deterioration of their already
existing peripheral vascular disease. There were no strokes; this was probably
related to the antegrade positioning and manipulation of the delivery system and valve. In 2 patients, a pace-maker was implanted to treat atrioventricular blocks. Three tamponades occurred, one; 4 hours after the procedure, with satisfactory recovery after surgical drainage, and other two patients; 2 days postoperatively, due to the rupture of the left ventricular apex, requiring emergent reintervention. This was followed by multiorgan failure and death at day 39. In-hospital mortality was 18% (8 patients), cause of in-hospital mortality were intractable arrhythmias and Left Ventricle (LV) failure in 2, septic shock in 2, and 4 patients died because of multiorgan failure. Mean follow-up was 8.6±5.6 (4–22) months. Six patients died after discharge (13%), cause of postdischarge mortality were pulmonary infection in 2 patients and LV failure in the other 4 patients. Late complications included pericardial effusion one month after TA-TAVI treated with surgical drainage. A false aneurysm of the apex of the left ventricle occurred 2 months after a transapical TAVI, and was treated by surgical closure with uneventful recovery.(9) There was no reintervention, hemolysis, or permanent valve-related impairment.
Table I. Demographics and patients’ characteristics
|
|
n=45 (%)
|
|
Age (years, mean±SD)
|
81±10
|
|
Female gender
|
17(45)
|
|
Diabetes
|
14(45)
|
|
Renal failure (creatinine>2 mg/dl)
|
8(45)
|
|
Severe COPD
(FEV1
<70% predicted and FEV1 / VC ratio <60%)
|
15(45)
|
|
NYHA class
II
III
IV
|
4
34
7
|
|
Coronary artery disease
|
31
|
|
Previous MI
|
13
|
|
Previous PCI
|
11
|
|
Previous CABG
|
13
|
|
Peripheral artery disease
|
19
|
|
Stroke
|
5
|
|
Cancer
|
12
|
|
Porcelain aorta
|
17
|
|
Other severe comorbidities
|
14
|
|
³ 2 comorbidities
|
26
|
|
Logistic EuroSCORE (%)
-Mean±SD
-Range
|
16±12
11-57
|
|
STS-PROM (%)
-Mean±SD
-Range
|
11±7
7-41
|
|
Aortic valve area
-cm²
-cm²/m²
|
0.72±0.17
0.46±0.09
|
|
Mean gradient (mmHg)
|
50±12
|
|
Systolic pulmonary artery pressure ³ 60 mmHg
|
9
|
|
LVEF (%)
|
49±13
|
Values are expressed as n (%) or mean±SD, unless otherwise stated.
Table II. Immediate
post-implantation results
|
|
Transapical TAVI (n=45)
|
|
Aortic valve area
-cm²
-cm²/m²
|
1.71±0.54
0.71±0.30
|
|
Mean gradient (mmHg)
-mean±SD
-range
|
7±4
2-10
|
|
Paravalvular aortic regurgitation
-Grade 0-I
-Grade II
-Grade III
|
14
0
1
|
|
Valve after valve
|
1
|
Values are
expressed as n (%) or mean ±SD, unless
otherwise
stated.
Discussion
The most
frequent indication for aortic valve replacement is age-related degenerative calcific AS.(10)
The operative mortality of AVR in elderly is higher than in the general population
and is approximately 7-10%.(11) Scores
predicting operative risk have been employed to provide an objective assessment
of potential mortality and morbidity for patients, with variable accuracy. The preoperative
work up of this study group predicted high surgical risk or technical
challenges to conventional AVR. Thus Transcatheter aortic valve implantation
techniques were considered as an alternative therapeutic solution. Patient
selecting for TAVI followed a multidisciplinary evaluation and included
patients with predicted mortality rate by EuroSCORE >20% and by STS
PROM>10%. The original cohort was
treated with the transfemoral approach as the first option, while the
transapical approach was reserved for patients refused both conventional surgery
and the transfemoral approach. The overall observed hospital mortality of
compares favourably with these predicted mortality rates. The fact that the
transapical approach is a more direct approach allowing surgical control of the
site of puncture and introduction of the necessary instruments may explain
procedural safety. The high post-procedure in-hospital death in the transapical
group correlates with the high risk in these patients who had severe peripheral
artery disease, frequent coronary artery disease, previous coronary artery
surgery and myocardial infarction, renal failure, and extra cardiac
comorbidities, all known to negatively affect survival.(9,15)
The selection process reserving the transapical approach to patients
contraindicated for the transfemoral approach can explain the high post
procedural mortality rate.(12)
Complications
of TAVI included access complications related to femoral puncture which in the
transapical group was performed to allow per procedure angiography and provided
immediate access to launch cardiopulmonary bypass in case of conversion.(13)
This was associated with significant complications and contributed to
death in one patient. No stroke occurred after TAVI in this study which seems a
consistent advantage of this approach.(14-16) Again, the more
direct approach and less manipulation with the aorta is a logical explanation
for a lower risk of stroke. Complete atrioventricular blocks requiring
pace-maker implantation concerned 4% of patients, and have been described in similar
ranges with the Edwards-SAPIEN prosthesis.(4,6,9) There was
no myocardial infarction, nor coronary obstruction, nor induced mitral valve
dysfunction, which confirmed the anatomical adequacy of the prosthesis to the
left ventricular outflow tract and the environing structures. Adequate
pre-procedure annulus sizing and continuous TEE monitoring during TAVI may have
contributed to this result.
Generally, initial procedural success rate is high
(93%).(17)
The SOURCE registry provided the results of the Edwards SAPIENTM valve
of 32 centers with 1038 patients. The implantation success rate of the
transapical procedure was above 90%. TA patients had a 30 day mortality of
10.3%. The stroke rate was 2.4% and pacemaker implantation rate was 6.7%.
Vascular complication rate was less than 3%.(18)
Complications
|
|
Transapical TAVI (n=45)
|
|
Major vascular complications
|
6
|
|
Stroke
|
0
|
|
Tamponade
|
3
|
|
Heart block requiring pace-maker implantation
In-hospital death
Cause:
Intractable arrythmias & LV* failure
Septic shock
Multiorgan failure
Postdischarge Mortality
Causes
LV failure
Pulmonary
infection
|
2
8(18%)
2
2
4
6(13%)
4
2
|
|
Duration of hospital stay
|
17±10
|
Values
are expressed as n (%) or mean ±
SD, unless otherwise stated
*
LV: Left ventricle
Limitation of the Study
Further analytical studies using larger numbers of
patients and longer time period are needed, i.e the 5-years overall survival
mortality using Kaplan-Meier method are needed.
Conclusions
Transcatheter aortic valve
implantation expands the scope of the treatment of aortic stenosis in high-risk
patients. While 2 different approaches have been advocated for valve
implantation, their results are influenced by the selection strategy. The TA
route provides a direct approach to the aortic valve and allows antegrade
manipulation of the instruments. There are no limits on the size of introducing
system and it is not affected by peripheral vessel tortuosity or disease. The
results at 2 years in high risk patients are encouraging.
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