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Circulation Journal Vol.76, February 2012
Circulation JournalOfficial Journal of the Japanese Circulation
Societyhttp://www.j-circ.or.jp
ortic stenosis is an age-related disorder that is charac-terized
by calcification of the aortic valve, local lipid accumulation,
inflammation, and neo-angiogenesis.1
Because the aged population is increasing, increased numbers of
patients are experiencing aortic stenosis, so the number of
patients requiring aortic valve replacement (AVR) is increas-ing.2
AVR still remains the standard therapy for symptomatic severe
aortic stenosis, although transcatheter aortic valve implantation
is considered as an alternative therapy for elderly patients at
high risk for perioperative complications.3 In Asian countries in
particular, female and elderly patients with aortic valve stenosis
often have a small aortic annulus.
Prosthesis-patient mismatch (PPM) is the difference bet-ween the
area of the implanted prosthetic valve and that of the patients
native valve without a stenotic lesion. Previous stud-ies have
shown that PPM, defined as an effective orifice area index (EOAI
ie, effective orifice area divided by body surface area (BSA))
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Circulation Journal Vol.76, February 2012
366 OKAMURA H et al.
University. All patients had previously granted permission for
use of their medical records for research purposes.
OperativeTechniquesAortic valve surgery was performed via
standard median ster-notomy. Cardiopulmonary bypass was initiated
after cannula-tion of the ascending aorta, superior vena cava, and
inferior vena cava. A left ventricular vent was inserted via the
right upper pulmonary vein. Antegrade/retrograde cold blood
car-dioplegia was administered intermittently to maintain cardiac
arrest. Moderate hypothermia was applied. After complete excision
of the diseased aortic valve, the diameter of the aortic annulus
was measured with sizers (St. Jude Medical) for selec-tion of the
appropriate prosthesis. The 17-mm St. Jude Medi-cal Regent
prosthesis was implanted in the intra-annular posi-tion with the
use of 2-0 polyester everting mattress sutures in 65 patients, 2-0
interrupted braided polyester sutures in 12 patients, and in the
supra-annular aortic position in 1 patient. Warfarin sodium was
started on the day of surgery and con-tinued thereafter so that the
international normalized ratio of prothrombin time was maintained
in accordance with Ameri-can College of Cardiology/American Heart
Association guide-lines. Operative data are shown in Table1.
EchocardiographyStandard M-mode dimensions were obtained
according to the American Society of Echocardiography criteria. The
mean of 3 measures from 2 different cardiac cycles was taken.
The
following variables were obtained: end-diastolic septal
thick-ness, left ventricular end-diastolic dimension, and
end-dia-stolic left ventricular posterior wall thickness. All
Doppler measurements were averaged from more than 3 cycles in
patients with sinus rhythm and more than 5 cycles in those with
atrial fibrillation. Maximum pressure gradients were cal-culated
from the complete Bernoulli equation. Left ventricular mass was
calculated according to the Devereux formula.7 The EOA was
determined by the standard continuity equation and indexed to
BSA.
Follow-upFollow-up transthoracic echocardiographic data were
ob-tained for 35 (45%) of the 78 patients at 13.310.8 (mean SD)
months after surgery. The clinical status of each patient was
evaluated by means of direct hospital visits and telephone
in-terviews. Follow-up was 100% complete. Mean follow-up was
32.619.6 months (range, 570 months). A major adverse valve-related
event was defined according to the guidelines for reporting after
cardiac valve interventions.8
StatisticalAnalysisData are reported as mean SD. Preoperative
and postopera-tive echocardiographic data for all patients were
compared and analyzed by paired Students t-test. Patients were
divided into 2 groups: with and those without PPM at discharge.
Dif-ferences between the groups were analyzed by chi-square test or
unpaired Students t-test as appropriate. Logistic regression was
used to identify factors associated with in-hospital death.
Variables were entered into multivariate analysis if univari-ate
analysis yielded a P-value
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Circulation Journal Vol.76, February 2012
367Mid-Term Outcomes With 17-mm Regent for AVR
age, preoperative NYHA class III or IV, hypertension, dia-betes,
and a concomitant procedure were associated with a major adverse
valve-related cardiac event. Multivariate analy-sis showed diabetes
to be the only independent predictor of a major adverse
valve-related cardiac event (Table3). Freedom from reoperation was
100%. Long-term survival and freedom from cardiac death are shown
in Figure2. Of the 76 survivors, 9 (12%) died during the follow-up
period: malignancy (n=2), heart failure (n=1), pneumonia (n=1),
renal failure (n=1), and unknown (n=4). Actuarial 1-year, 3-year,
and 5-year survival rate were 94.8%, 86.3%, and 78.7%,
respectively. Univariate analysis identified age, diabetes, renal
insufficiency, ejection fraction
1.5mg/dl.HR,hazardratio;CI,confidenceinterval.
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Circulation Journal Vol.76, February 2012
368 OKAMURA H et al.
EchocardiographicVariablesPreoperative echocardiography yielded
a mean aortic valve area index of 0.410.13 cm2/m2, a mean left
ventricular-aortic pressure gradient (LVAo-PG) of 59.021.5 mmHg,
and a mean left ventricular mass index (LVMI) of 17553 g/m2.
Follow-up echocardiography revealed a significant decrease in mean
LVAo-PG (16.66.8 mmHg), a significant decrease in LVMI (11632
g/m2), and a significant increase in mean
EOAI (0.970.21 cm2/m2). There was no significant difference
between the preoperative and postoperative ejection fractions
(0.600.14 vs. 0.630.07).
EffectofPPMonLong-TermSurvivalandEchocardiographicVariablesThe
EOA was obtained at discharge for 58 (74%) of 78 patients. Of these
58 patients, 18 (31%) had PPM with an
Figure2. Long-term postoperativesurvival and freedom from
cardiacdeath.
Figure3.
Follow-upechocardiograph-icvariablesofpatientswith(n=18)andwithout(n=40)prosthesis-patientmis-match(PPM)atdischarge.Follow-upvalue
in comparison to preoperativevalue.LVAo-PG,
leftventricular-aorticpressuregradient;LVMI,leftventricu-larmassindex.
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Circulation Journal Vol.76, February 2012
369Mid-Term Outcomes With 17-mm Regent for AVR
EOAI
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Circulation Journal Vol.76, February 2012
370 OKAMURA H et al.
prosthesis.20,21 These findings suggest that implantation of a
17-mm Regent valve provides not only excellent operative results
but also good survival, associated with the better hemo-dynamic
results. Minardi et al reported satisfactory hemody-namic
performance in 19 patients with the 17-mm Regent valve under
dobutamine stress as well as at rest.22
Garatti et al also showed good early and long-term out-comes
after AVR with a 17-mm mechanical valve, although their evaluation
included only the 17-mm Sorin Bicarbon Slim prosthesis (Sorin
Biomedica, Saluggia, Italy), and the 17-mm St. Jude Medical
Hemodynamic Plus (St. Jude Medical).23 It must be noted that the
follow-up periods were relatively short and the number of patients
in each study was small. So, we need to look more carefully into
the safety and effectiveness of the 17-mm valve in a large number
of patients.
The drawback of a mechanical valve is lifelong anticoagu-lation,
and close monitoring is required to prevent postopera-tive
complications, including thromboembolism and
antico-agulation-related bleeding. Some could argue that mechanical
valves (vs. bioprostheses) will increase mortality and morbid-ity
as a result of anticoagulation.24 However, in our series, we
encountered cerebral hemorrhage in 2 patients, accounting for a
linearized rate of 0.5% per patient-year, but no cerebral
infarction. These complication rates are comparable to those of
patients given a bioprosthesis. Aupart et al studied clinical
outcomes of AVR in 1,133 patients who received a biopros-thesis and
reported a bleeding complication rate of 0.3% per patient-year and
thromboembolism rate of 0.6% per patient-year.25 Despite the need
for lifelong anticoagulation in patients who receive a mechanical
prosthesis, some reports have indi-cated no significant differences
in postoperative quality of life, survival, or incidence of
complications between mechanical and biological valves.26
The effect of PPM on prognosis and cardiac function remains
controversial. Mohty et al indicated that PPM nega-tively
influences long-term survival in specific patient groups such as
those with low cardiac function or severe PPM.27 Moon et al
reported that PPM had a negative impact on long-term survival only
for patients 70 years of age or less.28 Vicchio et al showed that
in patients over age 70, severe or moderate PPM did not influence
long-term outcome, left ven-tricular mass regression or quality of
life.29 In our series, there was no difference in survival or
reduction in LVMI between patients with and without PPM, although
the incidence of severe PPM was low. Also, our study included only
a small number of patients with low cardiac function or severe
PPM.
Another mechanical valve currently available for a small aortic
annulus is the 16-mm ATS-Advanced Performance valve (ATS Medical,
Inc, Minneapolis, MN, USA). Kobayashi et al reported on 15 patients
in whom the 16-mm valve was implanted.30 There was no in-hospital
mortality or significant postoperative reduction of LVMI despite a
high incidence of PPM. However, some of their patients given the
16-mm valve showed no improvement in left ventricular diastolic
function at mid-term follow-up.
StudyLimitationsThe limitations of our study should be taken
into consider-ation. The main limitation is the relatively low
echocardio-graphic follow-up rate. Most of our patients were
followed up at another hospital or clinic, some of which were far
from the hospital where the operation was performed. In addition,
the study group comprised mostly elderly patients. Nearly half of
the patients were unable to return for echocardiographic
assessment. Whether or to what degree this low follow-up rate
affected our survival and LVMI regression data is unknown.
Furthermore, the low incidence of severe PPM in our series might
have obscured the potential affect of PPM on out-comes.
ConclusionsIn summary, the 17-mm Regent prosthesis produced
satisfac-tory results in terms of survival, physical capacity, and
hemo-dynamic performance. Thus, the 17-mm prosthesis could be a
reasonable alternative, especially in patients with a small aor-tic
annulus. Although we confirmed the safety and effective-ness of the
prosthesis over 33 months of follow-up, we need to evaluate
outcomes over a longer period and in a substan-tially large study
group.
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