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Brief Rapid Communication
One-Year Clinical Outcome After Minimally Invasive Direct
Coronary Artery Bypass
Roxana Mehran, MD; George Dangas, MD, PhD; Sotiris C. Stamou, MD, PhD; Albert J. Pfister, MD;
Mercedes K.C. Dullum, MD; Martin B. Leon, MD; Paul J. Corso, MD
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Background—Minimally invasive coronary artery bypass (MIDCAB) is a new surgical technique by which the left internal
mammary artery is anastomosed under direct visualization to the left anterior descending artery without cardiopulmonary bypass.
Methods and Results—We followed all 274 patients who underwent MIDCAB from the time it was introduced at a single
center. In-hospital and 1-year clinical events were source-documented and adjudicated. The in-hospital major acute
cardiac event rate was 2.2%; this included a 1.1% mortality rate. At 1 year, the respective rates were 7.8% and 2.5%.
When compared with the initial 100 procedures, the subsequent 174 procedures had shorter vessel occlusion times
(10⫾5 versus 14⫾6 minutes; P⫽0.009), times to extubation (6⫾3 versus 14⫾10 hours; P⬍0.001), and lengths of
hospital stay (2.1⫾1.9 versus 3.2⫾3.1 days; P⫽0.04). Cumulative 1-year adverse cardiac events were 11% in the initial
100 cases and 6% in the subsequent 174 cases (P⫽0.17).
Conclusions—Excellent clinical results can be achieved with the MIDCAB technique. The clinical adverse event rate may
decrease with accumulated experience. (Circulation. 2000;102:2799-2802.)
Key Words: coronary disease 䡲 surgery 䡲 grafting
M
inimally invasive direct coronary artery bypass grafting (MIDCAB) through a small left anterior thoracotomy without cardiopulmonary bypass has been employed
with increasing frequency in the past decade. Despite initial
encouraging morbidity and mortality results with the technique,1–3 concerns have been raised about the accuracy and
quality of the anastomosis between the left internal mammary
artery (LIMA) and the left anterior descending artery
(LAD).4 –7 Furthermore, MIDCAB results may depend on
surgical indications, the selection of patients undergoing the
procedure, and the technical experience of the surgeon.
The purpose of the present study was to investigate early
and late clinical outcomes after MIDCAB in a consecutive
series of patients who were followed for 1 year after the
procedure.
disease in patients with significant concurrent medical illnesses for
whom cardiopulmonary bypass posed a significant risk, such as
patients with chronic renal failure, diffuse atherosclerosis of the
ascending aorta, advanced age, or respiratory insufficiency8; and (3)
patients who had religious convictions that precluded the use of
blood products.
Hospital charts were prospectively reviewed, and patients were
followed clinically for 1 year. Clinical events were sourcedocumented and adjudicated. Data were recorded in the computerized database maintained by the Cardiovascular Research
Foundation.
Statistical Analysis
Descriptive statistics were largely employed. Comparisons were
preformed between the initial 100 cases and the subsequent 174
cases. Categorical variables were compared using Fisher’s exact test.
Continuous variables were expressed as mean⫾SD and compared
with Student’s t test. P⬍0.05 was considered significant. SPSS
software 9.0 was used.
Methods
A total of 274 patients underwent MIDCAB at the Washington
Hospital Center from June 1996 (when it was introduced) through
May 1998; the same group of cardiac surgeons operated on all
patients. We excluded the 3401 patients who underwent conventional coronary artery bypass grafting (CABG) and the 335 patients
who had beating heart (off-pump) CABG with a complete median
sternotomy.
Major indications for MIDCAB included (1) isolated disease to
the anterior descending or first diagonal artery; (2) multivessel
Results
Baseline characteristics are summarized in Table 1. Unstable
angina, diabetes, hypertension, and hyperlipidemia were frequent. The initial 100 cases included fewer patients requiring
redo-CABG than the subsequent 174 cases.
In-hospital results are presented in Table 2. Conversion to
on-pump CABG was required in only 1 patient. No patient
Received August 25, 2000; revision received September 29, 2000; accepted October 8, 2000.
From the Section of Cardiac Surgery, Washington Hospital Center (S.C.S., A.J.P., M.K.C.D., P.J.C.), Washington, DC, and Cardiovascular Research
Foundation (R.M., G.D., M.B.L.), New York, NY.
Dr Dullum serves as a consultant to Guidant Corporation, and Drs Pfister and Leon serve on the Guidant Corporation Scientific Advisory Board.
Correspondence to Roxana Mehran, MD, Cardiovascular Research Foundation, 55 East 59th Street, 6th Floor, New York, NY, 10022. E-mail
[email protected]
© 2000 American Heart Association, Inc.
Circulation is available at http://www.circulationaha.org
2799
2800
Circulation
December 5, 2000
TABLE 1.
Preoperative Characteristics
Age, y
Total
(n⫽274)
Initial
(n⫽100)
Subsequent
(n⫽174)
62⫾12
63⫾12
62⫾13
0.8
P
Male sex, %
71
68
76
0.1
Diabetes mellitus, %
23
21
25
0.5
Hypertension, %
59
62
57
0.4
Hyperlipidemia, %
72
70
74
0.6
Renal insufficiency, %
9
5
11
0.1
New York Heart Association class III/IV, %
3
2
4
0.2
Moderate/severe left ventricular dysfunction, %
Unstable angina, %
9
7
10
0.6
64
70
60
0.2
Canadian Cardiological Society angina class III/IV, %
57
59
56
0.6
Prior myocardial infarction, %
36
35
37
0.8
Prior cardiac surgery, %
13
4
18
5
6
5
0.8
34
1.0
Prior stroke, %
Prior angioplasty, %
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Body surface area, m2
34
2⫾0.2
34
2⫾0.2
2⫾0.2
0.001
0.6
Values are mean⫾SD or percent of patients.
needed a conversion to off-pump CABG via median sternotomy. Certain procedural variables seemed to improve with
accumulated experience.
The in-hospital major cardiac event rate was 2.2% (mortality rate, 1.1%). Angiograms for persistent postoperative
chest pain were performed in 3 patients (1%) and showed a
patent FitzGibbon grade A anastomosis.9
Clinical Outcome at 1 Year
At 1 year, the cumulative rates of major adverse cardiac
events and mortality were 7.8% and 2.5%, respectively
(Table 3). Adverse cardiac events rates at 1 year were 11% in
the initial 100 cases and 6% in the subsequent 174 cases
(P⫽0.17).
Causes of death in the initial 100-case subset were acute
myocardial infarction (n⫽2), stroke (n⫽1), and ruptured
aortic aneurysm (n⫽1). Causes of death in the subsequent
174-case subset were acute myocardial infarction (n⫽1) and
myocardial failure during emergent CABG (n⫽1). The latter
death occurred in a patient who developed acute occlusion of
the left main artery and underwent emergent percutaneous
transluminal coronary angioplasty and subsequent CABG 1
year after MIDCAB.
In the year after surgery, none of the patients who had
angiographic follow-up showed a restenosed (⬎50% diameter stenosis) arterial bypass conduit.
Discussion
The concept of employing minimally invasive techniques for
coronary revascularization proposes that patient morbidity
and, potentially, mortality can ultimately be reduced without
compromising the excellent results of conventional revascularization techniques. Despite encouraging early reports,1–3
concerns have been raised about the technical limitations of
and the accuracy/durability of the anastomosis in MIDCAB
surgery.10 –13 Moreover, patients must be carefully screened
for the procedure to ensure that they can tolerate single-lung
ventilation and that their forced expiratory volume within 1
second is ⬎60% of the normal value.
In the present study, we present the 1-year follow-up
results of the first 274 MIDCAB cases. One-year clinical
events were low, and there was a slight tendency for the event
rate to improve with accumulated technical experience.
MIDCAB for reoperative bypass surgery was less frequent
in the initial than in the subsequent phase of this study.
Recent reports suggest that redo-CABG patients have better
outcomes with off-pump than with on-pump CABG surgery.14,15 Avoidance of cardiopulmonary bypass has been
associated with decreased rates of postoperative platelet
dysfunction and systemic stress from inflammation.16 Overmanipulation of the atheromatous aorta may result in a
significantly increased risk of stroke after conventional onpump CABG.16 Not only does MIDCAB eliminate cardiopulmonary bypass, but it also obviates the need for aortic
manipulation.
Postoperative pain management is crucial for successful
early extubation. Because MIDCAB has been associated with
significant pain during the early postoperative period,17 a
more aggressive pain management protocol was adopted in
our institution to allow for early extubation, minimize patient
discomfort, expedite recovery, and permit early ambulation.
In addition to improved pain control, the very low rate of
postoperative atrial fibrillation may explain the short length
of hospital stay after MIDCAB.18
Perioperative Outcome
Berger et al13 recently reported the early in-hospital patency
rate of LIMA-to-LAD anastomosis without a stenosis ⬎50%
to be 91% after conventional on-pump CABG. In the present
study, despite the absence of angiographic follow-up, the
uneventful in-hospital recovery of ⬎99% of the entire cohort
seems encouraging for the MIDCAB operation. This is very
Mehran et al
TABLE 2.
Clinical Outcome After MIDCAB
2801
Operative and Postoperative Patient Characteristics and Results
Total
(n⫽274)
Initial
(n⫽100)
Subsequent
(n⫽174)
P
Operative data
Urgent surgery, %
5
Procedure duration, min
Grafted left anterior descending artery, %
4
0.4
134⫾21
138⫾24
7
132⫾20
0.04
98
98
97
0.9
Grafted diagonal artery, %
3
2
3
0.6
Vessel occlusion time, min
12⫾4
14⫾6
10⫾5
Transfusions, %
14
15
14
Time to extubation, h
9⫾6
14⫾10
0.009
1.00
6⫾3
⬍0.001
Postoperative (in-hospital) data
Major in-hospital adverse cardiac events, %
2
4
1
0.07
In-hospital mortality
1
1
0.6
0.5
Percutaneous coronary intervention
0.7
2
0
0.6
Repeat CABG
0.4
1
0
0.8
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Stroke, %
1
1
1
1.0
Reoperation due to bleeding, %
9
17
4
0.07
Graft occlusion, %
1
1
1
1.0
Prolonged ventilation (⬎24 hours), %
0.8
1
0.6
1.0
Pulmonary edema, %
1
1
1
1.0
Q-wave myocardial infarction
0
0
0
1.0
Non-Q-wave myocardial infarction, %
9
10
8
0.7
Acute noninflammatory pericarditis, %
29
26
31
0.3
Atrial fibrillation, %
10
12
9
0.4
3
2
5
0.3
2.5⫾2.3
3.2⫾3.1
2.1⫾1.9
0.04
Acute renal failure, %
Postoperative length of stay, d
Values are percentages or mean⫾SD.
close to the reported 98% in-hospital patency rate (with
possible obstructive stenosis) of LIMA-to-LAD anastomosis
after conventional on-pump CABG.13
Outcome at 1 Year
A recent report indicated an excellent graft patency rate of
LIMA-to-LAD anastomosis after MIDCAB19: early and
6-mont patency rates were 97% and 95%, respectively, with
a 3% reintervention rate. Despite the absence of early or late
angiographic confirmation of patency in this study, the low
repeat revascularization rate supports the safety of MIDCAB
as a surgical option for the treatment of coronary artery
disease.
TABLE 3.
Clinical Events at 1 Year
Total
(n⫽274)
Initial
(n⫽100)
Subsequent
(n⫽174)
P
Mortality
2
4
1
0.65
Q-wave myocardial infarction
1
0
1
0.7
Target lesion reintervention
CABG
Angioplasty
Major cardiac events
Values are percentages.
3
5
2
0.3
1
1
1
1.0
3
5
2
0.3
8
11
6
0.17
We documented a 1-year reintervention rate of 2.9% and a
1-year actuarial survival rate of 98%. These values were
statistically similar between the initial 100 cases and the
subsequent 174 cases, although mortality was arithmetically
higher in the former group. This small but encouraging
improvement in survival rate, as well as the durability of the
anastomosis during the course of the study, likely reflects the
importance of the learning curve in the long-term clinical
outcome of patients after MIDCAB.
Limitations
This was a retrospective study without angiographic followup. However, chart review, data entry, and adjudication of
cardiac events were independently performed according to
prespecified definitions. Multivariate analysis was not performed because of the very low total number of major events.
Conclusions
Excellent clinical results can be achieved with the MIDCAB
technique. The clinical adverse event rate may decrease with
accumulated experience.
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One-Year Clinical Outcome After Minimally Invasive Direct Coronary Artery Bypass
Roxana Mehran, George Dangas, Sotiris C. Stamou, Albert J. Pfister, Mercedes K. C. Dullum,
Martin B. Leon and Paul J. Corso
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Circulation. 2000;102:2799-2802
doi: 10.1161/01.CIR.102.23.2799
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