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ORIGINAL ARTICLE
Predictors of postoperative mortality after mitral valve repair:Analysis of a series of 164 patients
JOUNI HEIKKINEN, FAUSTO BIANCARI, JARI SATTA, ESA SALMELA,
TATU JUVONEN & MARTTI LEPOJARVI
Division of Cardiothoracic and Vascular Surgery, Department of Surgery, Oulu University Hospital, Oulu, Finland
AbstractBackground . Mitral valve repair (MVR) has been shown to achieve good long-term results. However, this procedure isassociated with relevant immediate postoperative mortality. The aim of this study is to identify those preoperative variablesassociated with an increased risk of 30-d postoperative death. Methods . One hundred and sixty-four patients underwentMVR at our institution from January 1993 to December 2000. Results . Eleven patients (6.7%) died during the immediatepostoperative outcome, a median of 14 d after surgery (range, 1�/29 d). One patient (1.3%) out of 80 who underwent MVRas lone procedure died on postoperative day 14 of cardiac tamponade. The mortality rate in those who underwent MVRassociated with other procedures was 11.9%. Multivariable analysis (154 patients included in the analysis) showed thatpatients’ age (p�/0.006, for an increase of 10 units: OR 4.33, 95% CI 1.53�/12.27), history of prior cardiac surgery(p�/0.006, OR 118.56, 95% CI 4.03�/3491.14) and NYHA functional class (p�/0.011, OR 5.66, 95% CI 1.49�/21.49)were significantly associated with an increased risk of postoperative death. The receiver operating characteristics (ROC)curve showed that patients’ age had an area under the curve of 0.762 (95% CI 0.622�/0.901, p�/0.004), its best cut-offvalue being 65 years (mortality, 13.4% vs 2.1%, p�/0.008, sensitivity 81.8%, specificity 62.1%, accuracy 63.4%). None ofthe patients older than 65 and with a history of prior cardiac surgery survived the operation. Conclusions . MVR isassociated with a relevant 30-d mortality risk in patients older than 65 years, with advanced NYHA functional class and ahistory of prior cardiac surgery.
Key words: Mitral valve regurgitation, mitral valve inefficiency, mitral valve repair, mitral valve replacement
Introduction
The repair of degenerative mitral valve regurgitation
has been shown to be an effective procedure with
durable results. This has led to an increased
use of techniques of repair over replacement
(1,2). Mitral valve repair (MVR) has been shown
to be a valid alternative also in the setting of
ischemic mitral valve regurgitation (3�/5) and even
when replacement of the aortic valve is indicated
(6). There is also some evidence that MVR
can achieve good long-term results in patients with
rheumatic mitral valve disease amenable to
repair (7). A minimally invasive approach for
MVR has been shown to be feasible and durable
and may likely contribute to reduce operative
mortality and morbidity (8,9).
In 1997, Muehrcke & Cosgrove (10) estimated a
mortality of 3.4% by combining data from nine series
of MVR. More recent series reported 30-d mortality
rates which varied from 0 (9) to 10% (4), an
observation suggesting that, along with surgical ex-
pertise, patient selection and indication for MVR may
significantly influence the immediate outcome. In
this regard, we planned the present study to identify
those variables which, in our experience, were asso-
ciated with an increased risk of postoperative death.
Patients and methods
This series includes 164 consecutive patients (mean
age: 60.7 years) who underwent MVR at our
institution from January 1993 to December 2000.
Figure 1 depicts the number of MVRs done each
Correspondence: F. Biancari, MD, PhD, Division of Cardiothoracic and Vascular Surgery, Department of Surgery, Oulu University Hospital, PO Box 21,
90029 OYS, Finland. Fax: �/358 8 315 2577. E-mail: [email protected]
Scandinavian Cardiovascular Journal. 2005; 39: 71�/77
(Received 21 July 2004; accepted 28 August 2004)
ISSN 1401-7431 print/ISSN 1651-2006 online # 2005 Taylor & Francis Group Ltd
DOI: 10.1080/14017430410004605
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year and shows an increase in number of MVRs
performed during the last years of this series. Any
MVR done as lone procedure or associated with any
other cardiac procedure was included in this study.
Data on pre-, intra- and postoperative variables were
collected retrospectively from patients’ records by a
single surgeon (J.H.). Data on postoperative out-
come after discharge from the cardiac surgery ward
were obtained by reviewing the hospital records
inclusive of data from all wards of our hospital. If
the patient was discharged to another hospital for
medical treatment or rehabilitation, outcome data
were retrieved from discharge records of these
institutions. Furthermore, patients were contacted
by mail and causes of late death obtained from a
national registry (Tilastokeskus).
Demographic data are summarized in Table I. A
coronary angiography was routinely performed to
assess the status of the coronary arteries and, in
patients who had previously undergone coronary
artery bypass surgery, of the bypass grafts. The
operation was performed through median sternot-
omy. Moderate systemic hypothermia and ante-
grade/retrograde cold blood cardioplegia were used
in all patients. Transesophageal echocardiographic
examination was carried out intraoperatively before
and after repair. Operative data are summarized in
Table II.
Postoperatively heparin was administered followed
by warfarin for about 3 months, unless patients had a
prosthetic valve or chronic atrial fibrillation which
indicated warfarin treatment indefinitely.
Statistical analysis was performed using SPSS
statistical software (SPSS v. 10.0.5, SPSS Inc.,
Chicago, IL, USA). Continuous variables are re-
ported as the median plus 25th and 75th interquartile
range. The x2-test and the Fisher’s exact test, with or
without the Monte Carlo method, were used for
univariate analysis of categorical data. The Mann�/
Whitney test was used to assess the distribution of
continuous variables in different subgroups. The
receiver operating characteristics (ROC) curve was
used for identification of the best cut-off value of age
in predicting postoperative adverse outcome. Logistic
regression with the help of backward selection was
used for multivariable analysis. Only preoperative
variables whose p B/0.05 at univariate analysis were
considered for inclusion in the regression model. A
p B/0.05 was considered statistically significant.
Results
Overall outcome
Echocardiographic data on postoperative degree of
mitral valve regurgitation were available for review in
152 patients. Transthoracic echocardiography
showed that in 80 patients (48.8%) there were no
signs of valve regurgitation, 59 patients (36.0%) had
grade 1 of regurgitation and 13 patients (7.9%)
grade 2 of regurgitation.
Eleven patients (6.7%) died during the immediate
postoperative outcome, a median of 14 d after
surgery (range, 1�/29 d). Data on main preoperative
variables and cause of death in these patients are
reported in Table III. The overall postoperative
complications encountered in this series are listed
in Table IV. Results of univariate analysis are
presented in Table V.
1993 1994 1995 1996 1997 1998 1999 20000
5
10
15
20
25
30
35
40
11.4%
10.3%
10.5%
0%0%
5.9%
0%
4.8%N
o. o
f M
VR
s/ye
ar
Overall no. of MVRs No. of MVRs associated with other procedures
Figure 1. Number of mitral valve repairs (MVRs) performed each year. Percentages represent the immediate postoperative mortality rate
for each year. The increase in number of MVRs performed during the last 2 years of this series is associated with an increase of associated
procedures. No significant association was observed between year of operation and postoperative mortality (p�/0.64).
72 J. Heikkinen et al.
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The regression model including all variables found
to be significant at univariate analysis failed to
identify any significant risk factor associated with
postoperative death. This may be due to the small
size of this series. However, this series includes
patients with such disparate preoperative conditions
along with technically different approaches, which
render the analysis somewhat complicated. Because
of this, we decided to include in the analysis only
those preoperative variables having most likely an
independent impact on the outcome. Thus, we
decided to exclude the type of atrial incision because
it is mainly related to surgeons’ preferences, calcifi-
cation as detected on preoperative echocardiography
because it does not correspond well with operative
findings, specific type of previous and concomitant
procedures because they are well represented by the
generic prior cardiac operation and concomitant
procedure variables. In the same way, cardiac index
well represented oxygen delivery (hemoglobin con-
centration and oxygen saturation did not signifi-
Table I. Preoperative risk factors.
No. (%)
Age 63.0 (53.1�/68.6)
Females/males 42 (25.6)/122 (74.4)Body surface area (m2) 1.9 (1.8�/2.0)
Body mass index (kg/m2) 25.6 (23.0�/28.0)
Asthma/chronic obstructive
pulmonary disease
12 (7.3)
Lower limb ischemia 7 (4.3)
Hypertension 26 (15.9)
Hyperlipidemia 14 (8.5)
Diabetes 16 (9.8)
Transient ischemic attack/stroke 8 (4.9)
Active endocarditis 0
Coronary artery disease 61 (37.2)
Previous myocardial infarction 21 (12.8)
Recent myocardial infarction 7 (4.3)
Unstable angina pectoris 4 (2.4)
Left main disease 11 (6.7)
NYHA functional class
I 4 (2.4)
II 69 (42.1)
III 59 (36.0)
IV 32 (19.5)
Atrial fibrillation 37 (22.6)
Mitral valve pathology
Annulus dilatation 4 (2.4)
Anterior leaflet disease 31 (18.9)
Posterior leaflet disease 88 (53.7)
Both anterior and posterior
leaflet involved
11 (6.7)
Ruptured chordae 59 (36.0)
Ruptured papillary muscle 1 (0.6)
Calcified valve 12 (7.3)
Etiology
Myxomatous degeneration 139 (84.8)
Rheumatic 3 (1.8)
Ischemic 6 (3.7)
Endocarditis 4 (2.4)
Penetrating trauma 2 (1.2)
No evident cause 10 (6.1)
Type
Mitral regurgitation 162 (98.8)
Mitral regurgitation and stenosis 2 (1.2)
Prior cardiac operation 11 (6.7)
Coronary artery bypass surgery 4 (2.4)
Atrial septal defect repair 4 (2.4)
Mitral valve repair 1 (0.6)
Aortic coarctation 1 (0.6)
Penthalogy of Fallot 1 (0.6)
Left ventricular ejection fraction (158 pts) 65 (57�/71)
Left atrium diameter (mm) (137 pts) 50 (46�/56)
Serum level of creatinine (153 pts) 91 (81�/102)
Serum level of hemoglobin (162 pts) 140 (131�/149)
Arterial oxygen saturation (%) (157 pts) 97 (96�/97)
Mean pulmonary artery pressure
(mmHg) (147 pts)
26 (20�/34)
Cardiac index (l/min/m2) (155 pts) 2.33 (2.02�/2.90)
Oxygen delivery (ml/min/m2) (150 pts) 420 (344�/514)
Continuous variables are reported as the median plus
25th and 75th interquartile range. NYHA�/New York Heart
Association.
Table II. Operative details.
No. (%)
Type of operation
Elective 131 (79.9)
Urgent 26 (15.9)
Emergent 7 (4.3)
Atrial incision
Superior 98 (59.8)
Transseptal 31 (18.9)
Lateral 28 (17.1)
Other 7 (4.2)
Findings at operation
Annulus dilatation 23 (14.0)
Anterior leaflet disease 28 (17.1)
Posterior leaflet disease 77 (47.0)
Both anterior and posterior leaflet in-
volved
31 (18.9)
Ruptured chordae 87 (53.0)
Ruptured papillary muscle 5 (3.0)
Calcified valve 2 (1.2)
Annuloplasty 155 (94.5)
Ring annuloplasty 101 (65.1)
Other 54 (34.8)
Leaflet resection and reconstruction 118 (72.0)
Shortening of the chordae 12 (7.3)
Chordae reconstruction with PTFE thread 34 (20.7)
Associated procedures 84 (51.2)
Coronary artery bypass surgery 58 (35.4)
Tricuspid valve repair 20 (12.2)
Atrial septal defect closure 10 (6.1)
Maze 8 (4.9)
Aortic valve replacement 1 (0.6)
Aortic clamping time (min) 135 (113�/177)
Cardiopulmonary bypass duration (min) 183 (154�/233)
Length of operation (min) 275 (240�/339)
Intraoperative bleeding (ml) 800 (500�/1275)
PTFE�/polytetrafluoroethylene.
Mitral valve repair 73
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Table III. Details on patients who died immediately after the operation.
Pts Gender Age
(years)
NYHA
functional
class
LVEF
(%)
Cardiac
index
(l/min/m2)
Preop. MV
regurgitation
grade
Cardiac
rhythm
Prior cardiac
surgery
Associated
procedures
Postop. MV
regurgitation
grade
Postop. day
of death
Causes of
death
1 Male 65.2 IV 32 �/ 3 AF CABG TVP 1 4 MI
2 Male 74.2 III 65 2.02 4 Sinus No No 0 14 Cardiac
tamponade
3 Male 63.3 III 67 1.99 3 FA No TVP 0 13 Bleeding from
trachestomy
4 Male 82.6 III 73 1.77 3 Sinus No CABG 0 25 MI
5 Male 69.5 III 65 1.57 4 FA MVA CABG 0 21 MOF
6 Male 65.7 IV 30 1.89 3 Sinus CABG CABG �/ 1 MI
7 Female 79.4 IV 72 1.37 3 FA No TVP 0 23 Sepsis
8 Male 77.2 IV 60 2.59 4 Sinus No CABG 2 8 MI
9 Male 73.0 III �/ 2.77 3 FA CABG,
ASD
CABG,
TVP,
ASD
�/ 21 MOF
10 Male 51.3 III 68 1.87 4 FA No Maze 1 7 Sepsis,
pneumonia
11 Female 67.7 IV 60 2.12 3 Sinus No CABG 2 29 MI
LVEF�/left ventricular ejection fraction; NYHA�/New York Association; MV�/mitral valve; MVA�/mitral valve annuloplasty; CABG�/coronary artery bypass grafting; ASD�/repair of atrial
septal defect; TVP�/tricuspid valve plasty; MI�/myocardial infarction; MOF�/multiorgan failure; �/�/unknown.
74
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cantly differ between survivors and patients who
died [p�/0.15, p�/0.67]), and mean arterial pressure
was excluded because it would have markedly
restricted the analysis to a few patients.
When patients’ age, NYHA functional class,
unstable angina pectoris, cardiac rhythm, baseline
cardiac index, history of prior cardiac surgery and
concomitant procedures were included in the regres-
sion model (154 patients included in the analysis),
patients’ age (median age of deaths/survivors: 69.4/
61.8 years; p�/0.006, for an increase of 10 units: OR
4.33, 95% CI 1.53�/12.27), history of prior cardiac
surgery (mortality rates with and without risk factor:
36.4% vs 4.6%, p�/0.006, OR 118.56, 95% CI
4.03�/3491.14) and NYHA functional class (mor-
tality rates: NYHA I: 0%, NYHA II: 0%, NYHA III:
10.2%, NYHA IV: 15.6%; p�/0.011, OR 5.66, 95%
CI 1.49�/21.49) were shown to be significantly
associated with an increased risk of postoperative
death. The ROC curve showed that patients’ age had
an area under the curve of 0.762 (95% CI 0.622�/
0.901, p�/0.004), its best cut-off value being 65
years (mortality in higher vs lower age category:
13.4% vs 2.1%; p�/0.008, sensitivity 81.8%, speci-
ficity 62.1%, accuracy 63.4%). Age significantly
correlated with baseline cardiac index (r : �/0.417,
p B/0.0001) and preoperative serum level of creati-
nine (r : 0.222, p�/0.006). Atrial fibrillation was
significantly associated with older age (median, 65.9
vs 60.8 years, p�/0.024).
Figure 2 depicts the increased mortality risk of
patients more than 65 years of age undergoing MVR
having a history of prior cardiac surgery.
Outcome of MVR as lone procedure
Among patients who underwent MVR as lone
procedure, only three patients had a history of prior
cardiac surgery. One patient (1.3%) died postopera-
tively. He was a 74-year-old man who underwent
elective operation and died of cardiac tamponade 14
d after surgery (Table III).
Outcome of MVR with concomitant procedures
Among 84 patients who underwent MVR associated
with other procedures, 10 (11.9%) died postopera-
tively. The postoperative mortality was similar when
the analysis was restricted to those patients who had
concomitant procedures other than Maze (9 out of
77 patients, 11.7%).
Univariate analysis showed that history of prior
cardiac operation (p�/0.006), age (p�/0.040), body
mass index (p�/0.017), NYHA functional class (p�/
0.024) and mean pulmonary artery pressure (p�/
0.023) were associated with increased risk of post-
operative death. When these were included in the
regression model, history of prior cardiac operation
(p�/0.05, OR 115.50, 95% CI 1.01�/13 228.35), age
(p�/0.027, for an increase of 10 units: OR 3.80, 95%
CI 1.12�/12.76) and NYHA functional class (p�/
0.032, OR 5.89, 95% CI 1.17�/29.80) were signifi-
cantly associated with an increased risk of post-
operative death.
Discussion
MVR has been established as the method of choice
in the treatment of mitral valve regurgitation. Beside
the satisfactory long-term results, some authors
reported markedly lower immediate postoperative
mortality in patients undergoing repair as compared
with replacement (3�/7,10,11). However, such lower
immediate mortality rates are likely due to selection
bias (3,4,6,7). Nevertheless, these observations sug-
gest that, when technically feasible, MVR is asso-
ciated with favorable operative outcome. Indeed, in
some series the mortality rates are rather relevant
Table IV. Postoperative complications.
Type of postoperative complications No. (%)
Postoperative bleeding requiring reoperation 22 (13.4)
Postpericardiotomy syndrome 20 (12.2)
Respiratory complications 19 (11.6)
Renal complications 6 (3.7)
Myocardial infarction 5 (3.0)
Stroke 5 (3.0)
Multiorgan failure 2 (1.2)
Transient ischemic attack 1 (0.6)
Wound complications 1 (0.6)
Mediastinitis 1 (0.6)
Table V. Risk factors significantly associated with postoperative
mortality at univariate analysis.
Risk factors p -value
Age 0.004
Unstable angina pectoris 0.023
Preoperative atrial fibrillation/pacemaker 0.036
NYHA functional class 0.005
Calcification at echocardiography 0.036
Prior cardiac operation 0.003
Prior coronary artery bypass surgery 0.001
Concomitant procedures 0.009
Concomitant procedures other than Maze lone 0.025
Concomitant tricuspid valve annuloplasty 0.031
Atrial incision 0.010
Baseline cardiac index 0.011
Baseline oxygen delivery 0.009
Mean pulmonary artery pressure 0.012
Cardiopulmonary bypass duration 0.042
Length of operation 0.017
Intraoperative bleeding 0.030
Mitral valve repair 75
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and this may call for a better preoperative patient
selection. The present study represents an attempt to
identify those risk factors associated with poor
immediate outcome. The small size of this series
and the rather large heterogeneity of this patient
population made the analysis somewhat complex,
but the results are sound and reflect current knowl-
edge about risk factors in heart valve surgery (11). In
particular, it seems that a conservative rather than
operative policy may lead many patients to reach an
advanced NYHA functional class in their old age.
We do not have data about the delay from the
diagnosis of mitral valve regurgitation to operation,
but the small number of patients in the present series
having had traumatic and ischemic mitral valve
regurgitation, suggests that most of the patients
have been symptomatic for some time before the
decision to operate was made on the basis of severe
symptoms. The increase in patient’s age further
increases the operative risk burden (3,8,12). Thus,
a watchful policy cannot be disregarded as a possible
cause of the present rather high operative mortality.
Repeat cardiac procedure is a well-known risk
factor in cardiac surgery. As shown in Figure 2, in
our experience this condition was invariably lethal in
patients older than 65. This observation calls for
possible contraindication to MVR in patients with
both these risk factors. However, some recent studies
(13�/17) have shown that patients undergoing mitral
valve surgery in the setting of prior cardiac surgery
can benefit from avoiding a repeat median sternot-
omy. Right thoracotomy, video-assisted minithora-
cotomy or port-access surgery have been shown to
be feasible in this setting and operative mortality
rates range from 0 to 5.7% (13�/17). These results
are remarkably better than our operative mortality
after MVR in a prior cardiac surgery setting
(36.4%). However, this approach is not feasible in
patients requiring concomitant procedures other
than those involving the atrioventricular valves.
Among patients who died postoperatively and having
been older that 65 and with history of prior cardiac
surgery, only one patient who underwent MVR and
tricuspid valve annuloplasty would have potentially
benefited from such minimally invasive approaches.
Nevertheless, these less invasive techniques should
be considered when feasible as they may reduce
mortality and morbidity in high-risk patients with or
without a history of prior cardiac surgery.
The present study showed that in about half of the
patients undergoing MVR, concomitant procedures
are required, the latter having been associated with a
relevant mortality. In those patients not requiring
any associated procedure, the mortality is very low.
However, this condition was not shown to be an
independent predictor of adverse outcome.
0
20
40
60
80
100
≥65 years
<65 years
No previous c
ardiac
operatio
n
Previous c
ardiac
operatio
n
Pos
top
tareiv
em
ort
lait
ytare
(%)
0%(0/7 pts)
2.2%(2/90 pts)
7.9%(5/63 pts)
100%(4/4 pts)
Figure 2. Increase of postoperative mortality after mitral valve repair by increasing age in patients with or without a history of prior cardiac
surgery (p B/0.0001).
76 J. Heikkinen et al.
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In conclusion, multivariable analysis identified
history of prior cardiac surgery, advanced age and
NYHA functional classes as independent predictors
of 30-d postoperative death. In patients older than
65 years and with prior cardiac surgery, the operative
risk is prohibitive as in our experience none with
both these risk factors survived after the operation.
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