1. Single IMA {Single Arterial}
Bi-Lateral Internal Mammary Artery (BIMA) Grafting Confers Improved Long-Term Survival After CABG Surgery Compared to Single IMA Grafting
Ryan P Kelly, Karen J Buth, Jean-Francois Légaré
Dalhousie University, Faculty of Medicine, Division of Cardiac Surgery, Halifax, Nova Scotia, Canada
Grafting Strategy
Long-Term Results
BACKGROUND: The primary objective of this study was to examine the effect of different arterial grafting strategies in CABG surgery on long-term mortality. METHODS: All consecutive CABG surgeries excluding redo operations performed at a single tertiary care center between were reviewed. Long-term survival rates were compared among patients based on the use of no arterial graft (all saphenous vein), single arterial graft, and multiple arterial grafts. Groups were also stratified based on the type of arterial grafts used (bilateral internal mammary arteries (BIMA) vs. multiple arterial grafts with only one IMA). Cox proportional Hazards ratio models were generated to adjust for differences in clinical presentation between the CABG groups. RESULTS: A total of 8570 isolated CABG operations were preformed at our institution during that period. These patients were followed for a median time of 3.5 years (IQR= ). In this patient population, a single arterial graft was performed in the majority of patients (63%; n=5637) with 28% of patients (n=2532) receiving multiple arterial grafts. Patients who received multiple arterial grafts were more likely to be young, male, and undergo non-urgent surgery. After adjusting for these differences, patients who received any arterial graft were shown to have improved survival when compared to patients who did not (HR=0.75; CI= ). However when single arterial grafts were compared to multiple arterial grafts no incremental survival benefit was apparent except for BIMA use. Among patients who received multiple arterial grafts, percent survival for patients with BIMA grafts at 10 years was 71.6% compared to 66.6% for multiple arterial without BIMA and 66.5% for patients with single arterial grafts (p<0.0001). CONCLUSIONS: We were able to show that after adjusting for differences in clinical presentation multiple arterial grafting, specifically with BIMA grafting, is a strong independent predictor of long-term survival among CABG patients. This observation emphasizes the benefit of BIMA grafting, and suggests that in suitable candidates BIMA grafting should be considered the ideal revascularization strategy.
Impact of BIMA Grafting on Survival Adjusted for Clinical Characteristics
Impact of BIMA Grafting on Readmission Adjusted for Clinical Characteristics
8570 Isolated CABG
5437 Single Arterial Graft
2448 Multiple Arterial Grafts
685 SVG Only
1079 BIMA Grafts
1369 IMA + Other
Background
CABG surgery is the established treatment for LM and multi- vessel CAD with excellent short and intermediate-term outcomes
Long-term results affected by vein-graft failure:
Intimal hyperplasia
Graft atherosclerosis
Strong evidence supports LIMA to LAD due to:
Superior graft patency
Fewer cardiac events
Enhanced survival compared to SVG alone
Is there survival advantage for bilateral internal mammary artery (BIMA) over Single IMA? ]
BIMA
BIMA *
Single IMA
Single IMA ] ] * *
SVG Only
SVG Only
SVG Only
Single IMA
BIMA
5 Year
82% (± 3%)
86% (± 2%)
88% (± 2%)
10 Year
59% (± 5%)
66% (± 4%)
71% (± 4%)
SVG Only
Single IMA
BIMA
5 Year
77% (± 4%)
83% (± 3%)
85% (± 3%)
10 Year
59% (± 6%)
68% (± 5%)
72% (± 5%)
6806 Single IMA
Number of patients at risk
BIMA
Single IMA
SVG Only
Number of patients at risk
BIMA
Single IMA
SVG Only
Univariate Analysis
Arterial Grafting
Adjusted Hazard Ratio
95% CI
p - value
BIMA
0.81
( )
0.0260
SVG Only
1.34
( )
0.0001
Arterial Grafting
Adjusted Hazard Ratio
95% CI
p - value
BIMA
0.86
( )
0.0580
SVG Only
1.39
( )
0.0002
Grafting Strategy
Methods
All consecutive CABG surgeries excluding redo surgery performed at a single tertiary care center between were reviewed
Univariate analysis of clinical characterstics by grafting strategy
Rate of long-term survival and readmission for cardiac cause were compared based on grafting strategy
Cox proportional hazards models were generated to adjust for differences in clinical characteristics between groups
Clinical Characteristics
SVG Only
n = 685 (%)
Single IMA {Single Arterial}
n = 5437 (%)
Single IMA
{IMA + other}
n = 1369 (%)
BIMA
n = 1079 (%)
p - value
Mean Age (SD)
70.2 (10.4)
65.5 (10.1)
62.0 (10.1)
58.5 (10.0)
<0.0001
Incomp Revasc
26.4
19.7
17.9
12.0
Female
34.9
26.6
18.6
18.0
BMI > 35
9.6
11.4
11.3
9.1
Diabetes
34.5
36.9
37.0
25.6
Renal Failure
12.3
5.5
3.0
1.8
PVD
25.0
16.8
14.3
CVD
16.6
13.9
10.2
9.4
COPD
23.2
14.2
12.9
10.7
EF < 40%
23.1
12.7
8.0
7.2
CHF
25.4
14.5
9.3
6.4
Urgent Status
36.2
16.1
10.0
9.7
LAD Disease
76.8
94.8
93.1
94.0
LAD Graft
71.8
98.1
96.1
96.5
Conclusions
Compared to the use of a single IMA or vein grafting alone, BIMA grafting independently predicts a long-term survival advantage and a significant reduction in the rate of readmission to hospital for cardiac cause including ACS, PCI, or CABG
In suitable candidates, BIMA grafting should be considered the ideal revascularization strategy