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Perioperative Cerebrospinal Fluid Drain Placement does not Increase Venous Thromboembolism after Complex Endovascular Aortic Repair
Brian J Fazzone
University of Florida, Gainesville, FL

Background: Incidence of venous thromboembolism (VTE) after thoracic and fenestrated endovascular aortic repair (TEVAR/FEVAR) is high (2-10%) and associated with increased mortality. Conversely, VTE occurrence after infrarenal EVAR is <1%; however, the etiology for this discrepancy remains unknown. Notably, patients undergoing TEVAR/FEVAR commonly undergo cerebrospinal fluid drain (CSFD) placement for neuroprotection, which requires interruption of perioperative anticoagulation and prolonged immobility. We hypothesized that CSFDs are a risk factor for VTE after complex endovascular aortic surgery.
Methods: All consecutive patients undergoing TEVAR and FEVAR at a single center were reviewed (2011-2020). Patients undergoing concomitant open surgery were excluded. CSFDs were placed based on surgeon preference preoperatively or for spinal cord ischemia (SCI) rescue therapy postoperatively. VTE was defined as any new extremity deep venous thrombosis (DVT) or pulmonary embolism (PE) confirmed on imaging within 30 days postoperatively. Routine VTE screening for asymptomatic patients was not performed. Univariate analysis was used to compare patients with and without VTE, as well as patients with and without CSFDs. Multivariate analysis was used to explore risk-adjusted associations between VTE incidence and CSFD placement.
Results: 932 patients underwent TEVAR/FEVAR. 42%(n=389) received a CSFD at some point in their care (pre-emptive, 94%[n=367/389]; post-operative SCI rescue therapy, 6%[n=22/389]). Patients with spinal drains were more likely to have a prior history of aortic surgery (44% vs. 35%, p=0.005) and received more postoperative blood products (800 vs. 450mL, p=0.02). Despite these differences, all other demographics, comorbidities, and perioperative characteristics were similar between patients with or without CSFDs (Table). The overall incidence of VTE was 2.7%(n=25): DVT, 1.8%(n=17); PE, 1.7%(n=16). Among TEVAR/FEVAR patients experiencing a postoperative VTE complication, 52%(n=13) were symptomatic. The vast majority of VTEs (92%, n=23) were identified in-hospital with an average time to diagnosis of 149 days postoperatively. VTE occurrence trended higher in patients who underwent either TEVAR alone or TEVAR+FEVAR compared to subjects receiving FEVAR (3.3% vs. 1.1%, p=0.07). Patients with VTE were younger (60 vs. 67 years, p=0.001), more likely to undergo non-elective surgery (96% vs. 43%, p<0.0001), have higher ASA classification (4.1 vs. 3.7, p=0.0007), require longer ICU admission (24 vs. 12 days, p<0.0001), and received more blood products (1764 vs. 569mL, p<0.0001). Overall, VTE incidence was 1.8% in patients with CSFDs compared to 3.3% in those without drainage (OR 0.47 [95%CI 0.19-1.13, p=0.10). However, patients receiving CSFDs postoperatively for SCI rescue therapy had a higher incidence of VTE (9.1% vs. 1.1%, p=0.04). Overall survival for patients with VTE was not different compared to patients without VTE (3636 vs. 4632 months).
Conclusions: CSFD placement was not associated with an increased risk of VTE in patients undergoing complex endovascular aortic repair. VTE incidence was higher in patients presenting non-electively and those with more complicated perioperative courses which identifies a high-risk phenotype that may justify different VTE prophylaxis and/or surveillance postoperatively.

Table. Comparison of demographics, comorbidities, perioperative characteristics, and VTE rates in TEVAR/FEVAR patients with and without cerebrospinal fluid drains.
All Patients (n = 932), %CSFD (n = 389), %No CSFD (n = 543), %P-value
Demographics
Age, mean (SD)67.2 (13.6)68 (12)67 (15)0.3
Female sex281 (30)119 (31)162 (30)0.9
Elective procedure515 (55)165 (42)252 (46)0.3
Comorbidities
History of cancer27 (3)9 (2)18 (3)0.5
Metastatic carcinoma3 (0.3)3 (0.8)0 (0)0.3
COPD332 (36)152 (39)180 (33)0.07
Diabetes174 (19)63 (16)111 (20)0.1
Liver disease45 (5)16 (4)29 (5)0.5
Renal disease214 (23)82 (21)131 (24)0.3
Myocardial Infarction125 (13)48 (12)77 (14)0.5
Cerebrovascular disease114 (12)45 (12)69 (13)0.7
Congestive heart failure141 (15)57 (15)84 (16)0.8
Ever smoker679 (73)288 (74)391 (72)0.6
Active smoker230 (25)95 (24)135 (25)0.9
Prior aortic surgery359 (39)171 (44)188 (35)0.005*
Perioperative characteristics
ASA Classification (SD)3.7 (0.6)3.7 (0.5)3.7 (0.6)0.4
Surgery Length (SD)291 (150)301 (152)284 (147)0.1
#ICU days (SD)12 (11)13 (12)12 (10)0.07
mL of Blood Products Transfused (SD)591 (1999)789 (2752)451 (1056)0.02*
Survival, Months (SD)45 (32)44 (31)46 (33)0.4
VTE
DVT17 (1.8)6 (1.5)11 (2)0.8
PE16 (1.7)12 (2.2)4 (1)0.2
Any VTE25 (2.7)7 (1.8)18 (3.3)0.2


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