07/08. tbl. 105. árg. 2019
No significant association between obesity and long-term outcome of coronary artery bypass grafting
Engin marktæk tengsl offitu og lifunar eftir kransæðahjáveituaðgerð
Objectives: Our objective was to investigate long-term outcomes of obese patients undergoing coronary artery bypass grafting (CABG) in Iceland.
Materials and methods: A retrospective analysis on 1698 patients that underwent isolated CABG in Iceland between 2001-2013. Patients were divided into four groups according to body mass index (BMI); Normal=18.5-24.9kg/m2 (n=393), ii) overweight=25-29.9 kg/m2 (n=811), iii) obese=30-34.9 kg/m2 (n=388) and iv) severely obese ≥35kg/m2 (n=113). Thirty-day mortality and short-term complications were documented as well as long-term complications that were pooled into major adverse cardiac and cerebrovascular events (MACCE) and included myocardial infarction, stroke, repeated CABG, percutaneous coronary intervention with or without stenting, and death. After pooling the study groups, survival and freedom from MACCE plots (Kaplan- Meier) were generated and Cox regression analysis used to identify predictive factors of survival. Average follow-up time was 5.6 years.
Results: Severely obese and obese patients were significantly younger than those with a normal BMI, more often males with identifiable risk factors of coronary artery disease (CAD) and a lower EuroSCORE II (1.6 vs. 2.7, p=0.002). The incidence of major early complications, 30-day mortality (2%), long-term survival (90% at 5 years, log-rank test p=0.088) and MACCE-free survival (81% at 5 years, log-rank test p=0.7) was similar for obese and non-obese patients. BMI was neither an independent predictor for long-term (OR: 0.98 95%-CI: 0.95-1.01) nor MACCE-free survival (OR: 1.0 95%-CI: 0.98-1.02).
Conclusions: Obese patients that undergo CABG in Iceland are younger and have an increased number of risk factors for coronary disease when compared to non-obese patients. However, BMI neither predicted long-term survival or long-term complications. The outcomes following CABG in obese patients are good in Iceland.
Tables and figures
Figure1a. Kaplan-Meier curves comparing overall survival of the four weight groups (p=0.088, log-rank test).
Figure1b. Kaplan-Meier curves comparing survival without MACCE (Major adverse cardiac and cerebrovascular event) of the four weight groups (p=0.7, log-rank test).
Table I. Comparison of preoperative patient demographics for patients in different BMI groups that underwent CABG surgery during the years 2001-2013 in Iceland. Values are mean with standard deviation or number (%).
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Total (n=1705) |
Normal weight (n=393) |
Overweight (n=811) |
Obese class I (n=388) |
Obese class II&III (n=113) |
p-value | |||||
| Age | 66 ± 9.4 | 67 ± 10 | 66 ± 9 | 65 ± 9 | 61 ± 9 | < 0.001 | |
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| Male | 1437 (82) | 304 (77) | 687 (85) | 315 (81) | 86 (76) | 0.007 | |
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Risk factors for cardiovascular disease
| Hypertension | 1143 (65) | 218 (55) | 530 (66) | 266 (68) | 93 (82) | < 0.001 |
| Diabetes | 280 (16) | 41 (11) | 116 (14) | 74 (19) | 41 (37) | < 0.001 |
| Dyslipidemia | 992 (56) | 203 (53) | 460 (58) | 224 (60) | 76 (72) | 0.006 |
| Smoking history | 1260 (56) | 268 (68) | 568 (70) | 300 (77) | 89 (79) | 0.006 |
| Family history of CAD | 910 (52) | 195 (52) | 431 (55) | 198 (54) | 62 (61) | 0.44 |
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*Coronary artery disease
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Other preoperative patient demographics
| EuroSCORE II | 2.2 ± 3.6 | 2.8 ± 3.9 | 2.2 ± 3.5 | 1.8 ± 2.4 | 1.6 ± 1.3 | < 0.001 | ||
| CCS class 3-4 | 1326 (76) | 283 (72) | 619 (76) | 298 (77) | 93 (82) | 0.51 | ||
| NYHA class 3-4 | 784 (44) | 175 (54) | 359 (54) | 174 (54) | 58 (62) | 0.49 | ||
| LVEF | 55 ± 9.9 | 55 ± 10 | 55 ± 10 | 55 ± 9,5 | 55 ± 8,6 | 0.58 | ||
| Three vessel CAD and/or left main stem disease | 1574 (90) | 346 (88) | 739 (91) | 346 (89) | 107 (95) | 0.12 | ||
| CKD* | 237 (14) | 59 (15) | 102 (13) | 53 (14) | 17 (15) | 0.09 | ||
| COPD | 126 (7) | 37 (9) | 48 (6) | 32 (8) | 4 (4) | 0.08 | ||
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*GSH<60 ml/min/1,73 m2 History of cardiovascular disease |
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| History of MI | 446 (25) | 114 (29) | 197 (24) | 102 (26) | 23 (20) | 0.18 | ||
| History of arrythmia | 179 (10) | 42 (11) | 77 (10) | 39 (10) | 13 (12) | 0.87 | ||
| History of valve disease | 41 (3) | 10 (3) | 21 (3) | 14 (4) | 4 (4) | 0.69 | ||
| Previous PCI | 369 (21) | 68 (17) | 177 (22) | 81 (21) | 28 (25) | 0.22 | ||
Preoperative medications
| Beta-blockers | 1184 (67) | 256 (68) | 537 (71) | 267 (72) | 90 (83) | 0.017 |
| Statins | 1318 (75) | 277 (74) | 599 (77) | 311 (83) | 95 (88) | <0.001 |
| Acetylsalicylic acid (aspirin) | 652 (30) | 116 (29) | 309 (39) | 136 (35) | 56 (50) | <0.001 |
| Heparin | 768 (44) | 169 (43) | 356 (44) | 160 (42) | 53 (47) | 0.58 |
| Clopidogrel | 64 (4) | 12 (3) | 30 (3,8) | 11 (2,8) | 6 (5,3) | 0.56 |
Table II. Operative variables, length of stay, short-term minor and major complications and 30 day mortality following CABG in Iceland 2001-2013, stratified by BMI. Values are mean with standard deviation or number (%).
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|
Total (n=1705) |
Normal weight (n=393) |
Overweight (n=811) |
Obese class I (n=388) |
Obese class II&III (n=113) |
p-value |
| OPCAB | 380 (22) | 90 (23) | 168 (21) | 90 (23) | 26 (23) | 0.71 |
| Lenth of operation(min) | 212 ± 52 | 207 ± 52 | 208 ± 55 | 219 ± 58 | 232 ± 61 | < 0.001 |
| Clamp time(min) | 46 ± 17 | 45 ± 16 | 47 ± 16 | 48 ± 20 | 49 ± 18 | 0.043 |
| LIMA used | 1652 (94) | 360 (91) | 767 (95) | 365 (94) | 111 (98) | 0.039 |
| No. of distal anastomoses | 3.5 (1-6) | 3.4 (1-6) | 3.5 (1-6) | 3.5 (1-6) | 3.5 (1-5) | 0.55 |
| Bleeding < 24 hrs, (ml) | 981 ± 1007 | 1075 ± 807 | 957 ± 614 | 974 ± 1707 | 897 ± 719 | 0.21 |
| Red blood cell transfusion(units) | 2.6 ± 5 | 3.3 ± 6 | 2.6 ± 4 | 2.2 ± 6 | 2.4 ± 5 | 0.005 |
| ICU stay (days) | 1.9 ± 3 | 1.9 ± 3 | 2 ± 3 | 1.7 ± 3 | 2 ± 3 | 0.43 |
| Total length of stay(days) | 11 ± 8 | 12 ± 8 | 11 ± 7 | 11 ± 8 | 13 ± 13 | 0.02 |
| Minor complications | 855 (49) | 195 (49) | 394 (48) | 186 (48) | 58 (51) | 0.92 |
| Superficial wound infection | 183 (10) | 39 (10) | 72 (8,9) | 43 (11) | 23 (20) | 0.003 |
| New onset atrial fibrillation/flutter | 579 (33) | 133 (34) | 282 (35) | 125 (32) | 30 (27) | 0.33 |
| Drainage of pleural effusion | 197 (11) | 65 (16) | 83 (10) | 32 (8) | 9 (8) | < 0.001 |
| Pneumonia | 115 (7) | 30 (8) | 52 (6) | 25 (7) | 6 (5) | 0.79 |
| Urinary tract infection | 62 (4) | 14 (4) | 24 (3) | 17 (4) | 5 (4) | 0.54 |
| Major Complications | 294 (17) | 76 (19) | 131 (16) | 60 (16) | 20 (18) | 0.46 |
| Acute kidney injury | 14 (1) | 4 (1) | 4 (0,5) | 4 (1) | 2 (2) | 0.27 |
| Deep sternal wound infectons | 16 (1) | 0 (0) | 8 (1) | 4 (1) | 2 (2) | 0.08 |
| Sternum dehischience | 27 (2) | 4 (1) | 12 (1) | 9 (2) | 2 (2) | 0.48 |
| Stroke | 23 (1) | 7 (2) | 8 (1) | 4 (1) | 3 (3) | 0.29 |
| Multi-organ failure | 55 (3) | 15 (4) | 25 (3) | 8 (2) | 6 (5) | 0.26 |
| 30 day mortality | 42 (2) | 12 (3) | 17 (2) | 9 (2) | 2 (12) | 0.77 |
Table IIIa. Independent risk factors for death following CABG in Iceland 2001-2013 (Cox regression analysis).
| Variables | HR | 95% CI | p-value |
| Diabetes | 1.98 | 1.48-2.66 | < 0.001 |
| Congestive heart failure, EF < 30% | 1.98 | 1.24-3.15 | 0.004 |
| Decreased kidney function* | 1.93 | 1.40-2.66 | < 0.001 |
| COPD | 1.65 | 1.13-2.40 | 0.009 |
| LVEF 30 – 50% | 1.24 | 0.96-1.62 | 0.1 |
| EuroSCORE II | 1.07 | 1.03-1.11 | < 0.001 |
| Age | 1.07 | 1.05-1.09 | < 0.001 |
| Year of operation | 0.91 | 0.87-0.96 | < 0.001 |
| Use of statins | 0.76 | 0.58-0.99 | 0.044 |
| Body mass index | 0.98 | 0.95-1.01 | 0.87 |
| *GSH<60 ml/min/1,73 m2 |
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Table IIIb. Independent risk factors for MACCE following CABG in Iceland 2001-2013 (Cox regression analysis).
| Variables | HR | 95% CI | p-value |
| Congestive heart failure, EF < 30% | 1.89 | 1.27 – 2.79 | 0.002 |
| History of percutaneous coronary intervention | 1.79 | 1.36 – 2.35 | < 0.001 |
| Decreased kidney function* | 1.53 | 1.17 – 2.00 | 0.002 |
| COPD | 1.41 | 1.03 – 1.93 | 0.034 |
| Diabetes | 1.35 | 1.06 – 1.72 | 0.014 |
| EuroSCORE-II | 1.07 | 1.04 – 1.10 | < 0.001 |
| Age | 1.03 | 1.02 – 1.04 | < 0.001 |
| Year of operation | 0.96 | 0.93 – 1.00 | < 0.035 |
| Body mass index | 1 | 0.98 – 1.02 | 0.95 |
| *GSH<60 ml/min/1,73 m2 |
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