19 декабря 2001 00:00 |
Clinical Outcomes and Angiographic Patency in 125 Consecutive
Background: This study compared clinical outcomes, length of stay,
and hospital costs in patients having
(OPCAB) versus conventional bypass surgery (CABG).
Methods: From November 1996 through April 9, 1999, OPCAB was
performed for 125 consecutive patients and compared with a
contemporaneous, matched control group of 625 CABG patients.
Patients were matched according to age, gender, incidence of renal
failure, diabetes, pulmonary disease, stroke (CVA), hypertension,
peripheral vascular disease, and previous myocardial infarction.
Results: An average of 2.0 grafts per patient were performed in the
OPCAB group (range 1−5).
total of 179 grafts assessed angiographically prior to hospital
discharge. All but 4/179 grafts (2.2%) were patent , including 94 of
94 IMA grafts (100%) . There
group compared to a mortality rate of 1.4% in the CABG group. OPCAB
reduced postoperative hospital stay from 5.5 days in the traditional
CABG group to 3.3 days (p=.002), with a decrease in hospital cost of
24% (p=.01). In addition, there was a significant reduction in the
rate of transfusion in the OPCAB group (29.6%) compared to the CABG
group (56.5%, p=.0001). Two OPCAB patients required postoperative
intervention to improve graft patency during
No internal mammary grafts required revision. There was one
perioperative CVA and one myocardial infarction in the OPCAB group.
Conclusions: OPCAB surgery reduces hospital cost, postoperative
length of stay , and transfusion rate compared to CABG. OPCAB is
safe, cost effective, and associated with excellent graft patency
and clinical outcomes.
In an attempt to avoid the deleterious effects of cardiopulmonary
rediscovered and refined. Coronary artery bypass graft surgery was
first performed without the use of extracorporeal circulation in the
late 1960s [Kirklin 1983]. This technique was largely abandoned
after the use of CPB and cardioplegic arrest became routine [Buffolo
Blood contact with artificial surfaces on the CPB circuit produces
well-documented diffuse inflammatory response which affects multiple
organ systems. Specific deleterious effects of the inflammatory
response have been documented in the heart, lungs, central nervous
system, kidneys, and gastrointestinal tract. Virtually all
detrimental effects of this diffuse inflammatory response increase
with increased duration of CPB [Edmunds 1997]. Also associated with
increased CPB time are increased hospital costs and length of stay
Multiple previous authors have reported series
[Benetti 1995, Buffolo 1996, Calafiore 1996, Calafiore 1998,
Bergsland 1998, Hart 1999]. While these authors have reported
excellent mortality rates, concern has been raised of a decrement in
graft patency rates [Subramanian 1997]. We previously described the
institution, and reported outcomes
determine the safety and efficacy
[Puskas 1998]. The present study reports clinical outcomes and
angiographic patency in 125 consecutive
compares these results
CABG on cardiopulmonary bypass.
MATERIALS AND METHODS
1996 through April 9, 1999 and underwent OPCAB by a single surgeon
at Crawford Long Hospital of Emory University. The comparison group
University Cardiac Surgical Database.
computer generated five control patients matched for age, gender,
the authors at the same institution during the same time period.
diabetes, renal insufficiency (creatinine greater than 2.0 mg/dl),
previous stroke, chronic obstructive pulmonary disease, peripheral
vascular disease, and previous myocardial infarction.
During the first few months of the study period, the procedure was
accomplished via minithoracotomy (MIDCAB; N = 9 patients) as
previously described [Puskas 1998]. The surgical technique then
evolved from a minithoracotomy to a median sternotomy incision. This
was prompted by concern about precision and safety with the limited
exposure afforded by minithoracotomy and by the very limited number
of patients referred for surgical management
disease at our institution. The remaining 116 patients underwent
off-pump operation through a median sternotomy incision. The
internal mammary artery (IMA , right or left) was harvested under
direct vision. Heparin administration has also evolved and now
consists of a full pump dose of 400 units/kg administered prior to
division of the internal mammary artery. This is partially reversed
with a half dose of protamine (typically 1mg/kg) after completion of
the last anastomosis. One of several commercially available
mechanical stabilizing devices was used for stabilization of the
coronary target(s) on the beating heart (United States Surgical,
Norwalk CT; Cardiothoracic Systems, Cupertino CA; Medtronic Octopus
II, Minneapolis MN; Genzyme, Boston MA). The target coronary
arteries were occluded proximally with a silastic vessel loop, and
retrograde bleeding was controlled with a sterile, humidified carbon
dioxide blower. Distal anastomoses were constructed with 7−0 or 8−0
monofilament suture. Proximal anastomoses were sewn to the aorta
under a partial occlusion clamp with 5−0 or 6−0 suture.
Intraoperative epiaortic ultrasound was performed to rule out
significant atherosclerosis of the ascending aorta prior to
application of the clamp. Evidence of significant atherosclerosis
(Grade III or higher) prompted alternative construction of proximal
anastomoses on the LIMA pedicle.
Data reflecting intraoperative and postoperative variables were
collected for comparisons. These data included the number of distal
grafts, use of the internal mammary artery as a conduit,
postoperatively, intubation for greater than 48 hours following
surgery, postoperative myocardial infarction, stroke, sternal wound
infection, leg wound infection, renal failure,
bleeding, transfusion requirements, atrial and ventricular
arrhythmias, postoperative length of stay, and hospital costs
associated with the operation.
In the early experience, any patient with a postoperative complaint
remotely suggestive of angina underwent angiography. Later, all
OPCAB patients were requested to consent to postoperative
angiography under our institutional quality assurance protocol.
Patients with preoperative renal insufficiency or severe
calcification/atherosclerosis of the ascending aorta were excluded
from postoperative angiography. In several other cases, patients or
referring cardiologists refused postoperative catheterization. A
angiography to document graft patency prior to hospital discharge.
None of the control patients had postoperative angiography.
Measures of central tendency, inferential, and multivariate
statistics were used for the data analysis. The frequency, mean, and
standard deviation were calculated for the independent and dependent
variables. The Student's
with continuous variables.
categorical variables. Comparisons between the two groups were made
by using logistic regression for the dichotomous dependent
variables. Multiple regression was used as a means to identify
independent predictors of length of stay and hospital charges. An
alpha level of .05 was used to determine significance [Bailar 1992].
grouped together and compared with control patients having CABG on
group included 625 patients for a total sample of 750 patients. The
two groups were compared on the basis of age, gender, and all seven
comorbidities listed above to ensure that the two groups were
appropriately matched [see Table 1]. The mean age was 61.0 years
(31% female and 69% male)
the control group (27.5% female and 72.5% male; p=.4). The groups
differed only in preoperative chronic obstructive pulmonary disease
(COPD) (25.6% OPCAB vs 20% traditional CABG; p = .04).
Table 2 compares clinical outcomes between the two groups. No
procedure. The mean number of distal anastomoses was significantly
higher in the control group (3.6 grafts per patient) when compared
with the OPCAB group (2.0 grafts per patient; p = .001).
There were no hospital deaths in the OPCAB group (0%) while there
were nine in the control group (0.64%). These results did not reach
statistical significance. Postoperative complications are presented
in Table 3. There was only one myocardial infarction in the OPCAB
patients (0.8%) as compared with an incidence of 0.5% in those
recieving traditional CABG (NS). A completed stroke occurred in 0.8%
with CPB. There was also a significant reduction in postoperative
group. Interestingly, there was no difference in the incidence of
atrial fibrillation between groups, despite the absence of atrial
sutures, cannulation, and extracorporeal circulation
group. Both groups received a similar postoperative regimen of
A striking difference was found between groups in the incidence of
postoperative transfusion requirements [see Table 4]. While more
than half of the patients in the control group required transfusion
of some blood product(s) during their hospitalization,
angiography prior to discharge: 175/179 grafts (97.7%) were widely
patent, 3/179 were totally occluded (1.6%; all vein grafts to
diagonal targets), and 1/179 anastomoses was narrowed > 50% (0.5%;
one vein graft to a posterior descending artery). All 94 internal
mammary graft anastomoses were widely patent [100%; see Table 5
:574:]. One patient had asymptomatic occlusion of a vein graft to a
diagonal target, with a widely patent
coronary artery (LAD) graft. One patient with undiagnosed protein C
and S deficiencies had uneventful
acute thrombosis of two vein grafts to diagonal coronary targets and
suffered a perioperative anterior myocardial infarction (MI). An
IABP was placed and she had urgent reoperation on CPB, with
replacement of her vein grafts. Subsequent repeat postoperative
catheterization documented patency of her original LIMA and both
reoperative vein grafts. She was discharged home on aspirin and
warfarin under the care of a hematologist. One patient had
asymptomatic stenosis of a vein graft to a small posterior
descending coronary artery. All other graft anastomoses were widely
patent on postoperative catheterization.
Dramatic differences in total postoperative length of stay and
hospital costs were found between groups [see Table 6]. Length of
stay was reduced by 40%, while hospital costs fell by 24%
off-pump group. CPB was found to be an independent predictor of
increased hospital cost and increased postoperative length of stay.
The multiple regression model for length of stay had a multiple R of
0.49, R squared of 0.24, F = 17.73, p=.00001. Significant variables
which contributed to the model of length of stay were CPB, atrial
arrhythmia, prolonged intubation, inotropic support > 48 hours,
sternal wound infection, and transfusion requirement. Additional
variables analyzed which were not independently significant included
postoperative stroke, and postoperative MI. When mortality was
included in the length of stay model, death was a significant
independent predictor [see Table 7].
The following variables contributed to a significant model
predicting hospital cost: CPB, postoperative renal failure,
transfusion, prolonged intubation and inotropic support,
any complication. Variables entered into the regression equation
that were not independently significant included the number of
grafts, postoperative stroke, and postoperative MI. The multiple R
was 0.62, R squared was 0.38, F = 19.9, p=.00001 for the cost model
[see Table 8].
conventional CABG patients matched from the database served as
controls for comparisons of perioperative events. There
follow-up of these control patients after hospital discharge.) All
OPCAB patients were telephoned and questioned regarding any
recurrent angina, myocardial infarction, cardiac reintervention,
hospital readmission, wound complications, infections, etc.
Two patients developed recurrent angina in the OPCAB group.
occlusions had an uneventful
to hospital with chest pain 12 months postoperatively. Cardiac
catheterization revealed a LIMA string sign and occlusion of the
saphenous vein graft to the right coronary artery. The diagonal vein
graft was widely patent, and the patient was managed medically.
Another patient very early in our experience had an OPCAB single
vessel vein graft to an intramyocardial ramus intermedius target.
Early angiography demonstrated that the graft was patent, but had
been misplaced to a small branch of the intended vessel. This graft
closed six weeks after discharge, and PTCA was performed to the
ramus intermedius, with resolution of angina symptoms.
There was one death after hospital discharge in the OPCAB group.
a porcelain aorta, moderate mitral regurgitation, and a 90% ostial
left main lesion had a single vessel OPCAB
discharged on postoperative day six and expired at home less than 30
days after hospital discharge. All other OPCAB patients are alive
and well without angina
Pioneered by Benetti and Buffolo in South America almost twenty
years ago, CABG without CPB has been recently rediscovered and
continues to be refined.
performed for lesions in virtually any coronary artery with
presently available instrumentation and a high degree of patient
safety and surgeon comfort. Clinical and angiographic results
described above support this statement. No patient
group had to be converted to CPB during the procedure. Surgical
management of lesions in the left circumflex territory formerly
required cardiopulmonary bypass at this institution and limited the
proportion of coronary cases which could be performed
less than 20%. We have considered complete revascularization to be
the «gold standard» for coronary bypass surgery irrespective of the
surgeon's choice of incision or use of cardiopulmonary bypass, and
still hold this belief. Incremental improvements in surgical
technique, including the routine use of wide bilateral transverse
diaphragmatic pericardiotomies, multiple deep pericardial traction
sutures and rotation of the heart into the right pleural space have
recently allowed visualization of obtuse marginal coronary targets
in a high proportion of patients. This has led to a recent sharp
increase in the number of grafts per patient in the OPCAB group [see
Figure 1]. The very recent commercial introduction of improved
mechanical stabilizer devices has also contributed significantly to
a fundamental shift towards OPCAB [see Figure 2]. Presently, over
80% of all CABG cases may be safely
OPCAB surgeon, including those requiring grafts to the obtuse
marginal branches of the left circumflex artery .
The preoperative differences between the OPCAB and CABG groups [see
Table 1] reflect the evolving bimodal pattern of patients referred
specifically for OPCAB. The first is a small group of young, healthy
patients who have failed PTCA for single or double vessel disease
and the second, a growing number of older, sicker patients with
relative or absolute contraindications to cardiopulmonary bypass.
This latter group has multiple severe comorbidities, often including
peripheral vascular disease including unilateral or bilateral
carotid occlusion. These patients often have been refused CABG in
the past. Thus, the incidence of severe COPD in the OPCAB group was
so high compared to patients undergoing conventional CABG that the
Emory University Cardiac Surgical Database could not match
completely for this variable, given the other constraints imposed in
the matching program. This resulted in the observed preoperative
difference between groups with respect to incidence of COPD.
The emphasis of minimally invasive cardiac surgery is on less
invasive techniques which may decrease cost, length of hospital
stay, and the overall morbidity associated with cardiac surgery. As
older, sicker patients are referred for coronary bypass surgery, an
increasing proportion of patients may have relative
contraindications to CPB. The present study demonstrated that CPB is
a statistically significant independent predictor of hospital cost
and length of stay.
The early angiographic patency rates presented here equal or exceed
all published series for coronary bypass on CPB, and are encouraging
relative to many earlier series of MIDCAB and OPCAB results [Mack
1998]. All 94 internal mammary anastomoses and all but 4 of 179
total grafts studied prior to hospital discharge were widely patent.
This is clear evidence that careful technique and use of advanced
mechanical stabilizer devices permit reproducible, precise
construction of coronary bypass anastomoses on the beating heart.
All routine conduits (LIMA, RIMA, radial artery, saphenous vein)
were used in this series to bypass all named coronary targets,
including the obtuse marginal branches of the left circumflex
coronary artery. Clinical outcomes during a mean 15 months
follow-up strongly suggest that these excellent early outcomes in
the OPCAB group are maintained over time. Nonetheless, the
conclusions from this series are weakened by its short period
follow-up and its retrospective
matched for multiple indices of perioperative risk. Only a large,
prospective, randomized, longitudinal comparison of graft patency
and clinical outcomes after coronary bypass surgery performed with
and without the use of cardiopulmonary bypass can ultimately
validate the safety, efficacy, and superiority
Presented at the Annual Meeting of the International Society for
Minimally Invasive Cardiac Surgery, Palais dés Congres, Paris,
France , May 21−22, 1999.
Reprint requests to: John D. Puskas, MD, MSc, Assistant Professor of
Surgery, Emory University, Carlyle Fraser Heart Center, Crawford
Long Hospital, 550 Peachtree Street, NE, Suite 7700, Atlanta, GA
30365; Phone: 404−686−2513; Fax: 404−686−4959;
Submitted on: Peer reviewed and accepted at the International
Society for Minimally Invasive Cardiac Surgery's 2nd Annual Meeting
and Scientific Sessions, Paris, France, May 21−22 1999.
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