Southern Association For Vascular Surgery

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Anemia and Postoperative Outcomes after Elective Abdominal Aneurysm Repair
Hanaa Dakour Aridi, Besma Nejim, Nawar Paracha, Widian Alshwaily, Satinderjt Locham, Mahmoud Malas
Johns Hopkins University, Baltimore, MD

Introduction: Anemia is associated with increased cardiac adverse events during the early postoperative period due to high physiologic stress and increased cardiac demand. The aim of this study is to assess the surgical outcomes and prognostic implications of anemia in AAA patients.
Methods: A retrospective analysis of all patients who underwent open (OAR) or endovascular (EVAR) AAA repair in the Vascular Quality Initiative Database (2008-2017) was performed. We excluded patients with preoperative polycythemia, ruptured aneurysms and patients transfused with more than 4 units of packed RBC to avoid inclusion of patients with blood loss anemia. The primary outcome was in-hospital Major Adverse Cardiac Events (MACE), defined as the occurrence of Myocardial Infarction (MI), stroke or death. Based on the location of knots (significant change in slopes) in the cubic spline model, hemoglobin (Hb) levels were categorized into 3 groups: Severe anemia (< 10 g/dl), mild anemia (10-12g/dL in females, and 10-13 g/dL in males), and no anemia (>12 &>13 in females and males, respectively). Multivariate logistic regression analysis adjusting for patientsí demographics, symptomatic status, comorbidities (Diabetes, HTN, CAD, CHF, COPD, CKD), preoperative medications as well as aneurysm diameter, intraoperative blood loss and concomitant procedures was performed.
Results: A total of 34,397 patients were included. Of those, 28.5% had mild anemia and 4.3% had severe anemia. In both OAR (n=6,112) and EVAR (n=28,285), patients with severe anemia had significantly higher rates of mortality, MI, MACE, renal and respiratory complications and reoperation compared to patients with mild or no anemia. They also had longer operative times as well as ICU and hospital stay (Table). In addition, EVAR patients with severe anemia also had higher rates of acute CHF, dysthymia, bowel and leg ischemia compared to patients with mild or no anemia. On multivariate analysis, severe anemia in patients undergoing OAR was associated with 80% higher odds of in-hospital MACE [OR (95%CI):1.83(1.32-2.53), p<0.001) and almost double the odds of 30-day mortality [OR(95%CI:1.91(1.10-3.29),p=0.02]. In EVAR; severe anemia was associated with double the risk of MACE [OR(95%CI:1.98(1.43-2.74)] and almost three folds the risk of 30-day mortality [OR(95%CI:2.92 (1.86-4.58)] (p<0.001) while mild anemia increased the odds of MACE by 40% [OR(95%CI:1.37 (1.09-1.73)] and 30-day mortality by 56%[OR(95%CI:1.56 (1.12-2.15)]. Interestingly, preoperative blood transfusion in mildly anemic patients undergoing EVAR was associated with 2.3 times the odds of MACE [OR (95%CI):2.3 (1.39-3.75), p<0.01].
Conclusions:Severe anemia is an independent predictor of MACE and 30-day mortality after AAA repair. Blood transfusion for mild anemia pre-EVAR significantly increases adverse cardiac events. Thus, medical management of anemia in these patients might be a better option than transfusion. These findings highlight the need to incorporate anemia into the preoperative risk assessment of patients undergoing AAA repair and to identify a safe Hb threshold to transfuse patients.

Univariate Analysis of Perioperative Outcomes in Open AAA repair and EVAR in the three Study Groups
Open (N=6,112)EVAR (N=28,285)
None (n=4,288)Mild
(n=1,569)
Severe
(N=255)
p-valueNone (n=18,827)Mild
(n=8,238)
Severe
(N=1,220)
p-value
Primary Outcomes, n (%)
In-hospital Mortality91 (2.1)61 (3.9)15 (5.9)<0.00161 (0.3)83 (1.0)43 (3.5)<0.001
Myocardial infarction (MI)
Troponin only112 (2.6)53 (3.4)13 (5.1)0.0368 (0.4)68 (0.8)20 (1.6)<0.001
EKG or Clinical75 (1.7)21 (1.3)7 (2.8)0.2356 (0.3)42 (0.5)12 (1.0)<0.001
Total MI187 (4.4)74 (4.7)20 (7.8)0.04124 (0.7)110 (1.3)32 (2.6)<0.001
Stroke31 (0.8)14 (1.0)2 (0.8)0.8231 (0.17)27 (0.34)3 (0.25)0.03
MACE (Stroke/Death/MI)268 (6.3)127 (8.1)35 (13.7)<0.001194 (1.0)192 (2.3)71 (5.8)<0.001
Mortality (30-day)
(% Follow-up =66.4)
93 (2.2)64 (4.1)17 (6.7)<0.001101 (0.5)131 (1.6)58 (4.8)<0.001
Secondary Outcomes
Length of Stay (days), median (IQR)7 (5-9)7 (6-10)8 (6-12)<0.0011(1-2)2 (1-3)3 (1-6)<0.001
ICU Stay (days), median (IQR)3 (1-4)3 (2-5)4 (2-6)<0.0010 (0-1)0 (0-1)0 (0-2)<0.001
Procedure Time (min), mean (SE)242 (98)252 (104)270 (117)<0.01130 (66)141 (73)156 (85)0.01
CHF145 (3.4)72 (4.6)11 (4.4)0.09104 (0.6)106 (1.3)41 (3.4)<0.001
Dysrhythmia488 (11.4)192 (12.3)32 (12.6)0.60373 (2.0)259 (3.2)50 (4.1)<0.001
Renal Events
Change in Cr>0.5 mg/dl541 (12.7)297 (19.0)47 (18.4)<0.001413 (2.3)339 (4.2)114 (9.6)<0.001
Temporary dialysis59 (1.4)28 (1.8)8 (3.1)14 (0.1)32 (0.4)12 (1.0)
Permanent dialysis29 (0.7)20 (1.3)8 (3.1)15 (0.1)24 (0.3)25 (2.1)
Total629 (14.7)345 (22.0)63 (24.7)<0.001442 (2.4)395 (4.9)151 (12.8)<0.001
Bowel Ischemia149 (3.5)59 (3.8)12 (4.7)0.5557 (0.3)43 (0.5)16 (1.3)<0.001
Leg Ischemia106 (2.5)28 (1.8)8 (3.1)0.21135 (0.7)78 (1.0)29 (2.4)<0.001
Respiratory Complication (Pneumonia or Ventilator)434 (10.1)204 (13.1)38 (14.9)<0.01229 (1.2)180 (2.2)64 (5.3)<0.001
Reoperation288 (6.7)124 (7.9)33 (12.9)<0.01301 (1.6)197 (2.4)83 (6.8)<0.001


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