Ashrani, Aneel A.

Abstract Introduction Anticoagulant therapy in individuals with cirrhosis is challenging, as their risk of hemorrhage is significant due to concomitant alterations in primary hemostasis, secondary hemostasis and fibrinolysis. For many years, warfarin and heparin (including low molecular weight heparin) were the only treatment options for patients with thrombosis. Since 2010, novel, direct-acting oral anticoagulants (DOAC) that inhibit either thrombin (dabigatran) or factor Xa (e.g., rivaroxaban, apixaban, edoxaban, and betrixaban) are available. These direct-acting oral anticoagulants do not require laboratory monitoring and have minimal food and drug interactions, which makes them appealing to use for many patients. Unfortunately, there is inadequate data about efficacy and safety of these direct oral anticoagulants in cirrhotic patients as this group was commonly excluded from clinical trials evaluating these medications. In our study we aim to describe a large single institution experience with use of DOACs in patients with cirrhosis and explore clinical characteristics as potential predictors for bleeding and thrombosis. Methods: We conducted a retrospective cohort study of patients with cirrhosis who were seen in our institution between September 1, 2010 and June 30, 2017 and were treated with a DOAC utilizing a database search tool, called the Advanced Cohort Explorer that allows electronic records to be reviewed in a time efficient manner through text search or code search functionality. Only patients with cirrhosis diagnosed by histopathologic evaluation or with clinical presentation consistent with cirrhosis and confirmed by a gastroenterologist or by radiologic imaging (MRI, CT) were included in the study. Results: In our study, 106 individuals (male=72) met the inclusion criteria. Ninety three (88%) patients were treated with an anti-Xa inhibitor (rivaroxaban or apixaban), and remaining 13 (12%) with direct thrombin inhibitor (dabigatran). Median age at starting anticoagulant was 66 (range 24-89) years. The most common indication for anticoagulation was atrial fibrillation/flutter (54%), followed by pulmonary embolism/deep vein thrombosis (19%) and splanchnic vein thrombosis (15%). At the time of DOAC initiation, the median Charlson comorbidity index (CCI) was 7 (range 3-15); MELD score was 10 (range 6-24); and platelet count 150,000/ul (range 50,000-432,000). Thirty six (34%) patients had objectively diagnosed varices. Median follow up was 563 days (range: 7-2646). Bleeding requiring medical evaluation occurred in 32 (30.2%) patients. Major bleeding as defined by ISTH was experienced by 12 (11.3%) individuals. The most common source of bleeding was gastrointestinal tract (21.7%); other organs were less commonly affected (table 1). Hemorrhagic complication usually occurred early after starting anticoagulation (median 101 days; range 4-1356), and was the most common reason for discontinuation of anticoagulant treatment (14%), followed by completion of treatment (10%). On Cox proportional hazard modeling, rising BMI (HR: 1.032 per unit increase in BMI; p<0.05) and elevated bilirubin (HR: 1.223 per 1 mg/dL increase) were associated with increased risk of bleeding. Other clinical factors, including sex, type of anticoagulant used, platelet count, PT/INR, albumin, MELD score, varices, portal hypertension, concomitant aspirin use, and Charlson comorbidity index were not associated with bleeding risk. Thrombotic events while on DOAC affected 7 (6.7%) individuals, which included venous thrombosis in 4 (3.8%) and arterial thrombosis in 3 (2.9%) patients. No clinical factors were associated with increased risk of thrombosis. Conclusions: Our study is the largest series of patients with cirrhosis treated with DOACs. Bleeding complications with DOAC use in this population is high. Providers considering starting DOACs in patients with cirrhosis should consider the risk of bleeding in this population. Disclosures No relevant conflicts of interest to declare.

Abstract Background: Active cancer without or with chemotherapy is associated with a 4- to 6.5-fold increased risk for VTE 1. However, cancer-associated VTE incidence may be under- or overestimated by reports that linked cancer registry data to an anticoagulation clinic database or to hospital discharge diagnosis codes 2–5. Objective: To estimate the incidence of VTE in active cancer in a well-defined geographic population that includes the full spectrum of VTE events (including rapidly fatal events) occurring in the community. Methods: Using the longitudinal resources of the Rochester Epidemiology Project and Mayo Clinic Tumor Registry, we identified all Olmsted County, MN residents with incident VTE by review of their complete medical records in the community 6, and all residents with active cancer (by cancer site), over the 28-year period, 1973–2000. Using residents with active cancer within the three months prior or subsequent to incident VTE as the numerator, and all residents with active cancer as the denominator, we estimated the incidence of VTE in active cancer, both overall and for the subsets of pancreatic cancer, brain cancer and lymphoma. Results: Over 78,236 active-cancer person-years, 595 Olmsted County residents developed incident VTE. The overall active cancer-associated VTE incidence was 760 per 100,000 person-years (95% CI: 701, 824), about 6.5-fold higher than the general population 7. Over 473, 983 and 4,258 pancreatic cancer, brain cancer and lymphoma person-years, respectively, 51, 18 and 46 residents developed incident VTE. The pancreatic cancer-, brain cancer- and lymphoma-associated VTE incidence rates were 10,784 (95% CI: 8029, 14,179), 1,831 (95% CI: 1085, 2,893) and 1,080 (95% CI: 791, 1,441) per 100,000, respectively. Overall, cancer-associated VTE incidence increased with age, and for all ages, men had a higher VTE rate than women. We observed a much higher pancreatic cancer-associated VTE incidence than previously reported. Conclusions: The incidence of VTE in individuals with active cancer (especially pancreatic cancer) is higher than the general population. The incidence of VTE in patients with pancreatic cancer is higher than previously estimated.

Abstract Introduction: Diabetes mellitus is often cited as a VTE risk factor. However, persons with diabetes are frequently hospitalized for medical illness or undergo surgery, both major VTE risk factors. Thus, the association of VTE with diabetes independent of surgery or hospitalization is uncertain. Methods: Using longitudinal, population-based Rochester Epidemiology Project resources, we identified all Olmsted County, MN residents who met objective criteria for incident VTE over the 25-year period, 1976–2000 (n=1922), and one to two controls per case, matched on age, gender, Olmsted County residency, and length of medical history (n=2115). For cases and controls, we reviewed their complete medical history in the community for baseline characteristics previously identified as independent VTE risk factors, including clinically-diagnosed diabetes mellitus. We tested diabetes as a potential VTE risk factor both alone and after adjusting for other baseline characteristics, and in the subset of cases with idiopathic VTE, using conditional logistic regression. Results: Among all cases and controls, 231 (12%) and 199 (9.4%) had diabetes, respectively. Univariately, diabetes was associated with overall VTE (odds ratio [OR]=1.32; 95% CI: 1.07, 1.62; p=0.009). However, after controlling for body mass index (OR=1.04, p<0.001), hospitalization with major surgery (OR=25.2, p<0.001) or hospitalization for medical illness (OR=7.3, p<0.001), active cancer (OR=8.3, p<0.001) and varicose veins (OR=1.3, p=0.003), diabetes was no longer associated with VTE (OR=1.09; 95% CI: 0.85, 1.41; p=0.49). Among 458 idiopathic VTE cases and 518 matched controls, 43 (9.4%) and 46 (8.9%) had diabetes, respectively. Diabetes was not associated with idiopathic VTE (OR=1.07, 95% CI: 0.69, 1.67; p=0.76). Conclusions: Diabetes mellitus is not an independent risk factor for overall or idiopathic incident VTE.

Abstract Abstract 4332 Background: Hemolytic anemia caused by the passive transfer of isoagglutinins, typically anti-A or anti-B antibodies, is a rare and likely under-recognized complication of intravenous immunoglobulin (IVIG) therapy. The Immunohematology Reference Laboratory at Mayo Clinic Rochester has detected 12 cases of passively acquired isoagglutinins following IVIG administration during the first seven months of this calendar year (January-July 2011). This frequency of detection is much higher than that seen over the three prior calendar years, when only two cases were detected. Given this “cluster” of isoagglutinin detection, we analyzed these 12 cases to determine the clinical significance of this finding as well as characteristics of resulting cases of hemolytic anemia. Materials/Methods: Charts of patients identified as having passively acquired isoagglutinins following IVIG therapy were analyzed for evidence of a significant drop in hemoglobin (defined as >1 g/dL) as well as evidence of hemolysis (elevated lactate dehydrogenase, reticulocytosis, spherocytosis, decreased haptoglobin, indirect hyperbilirubinemia, hemoglobinemia and hemoglobinuria). Cases with a >1 g/dL drop in hemoglobin and two or more of the above findings consistent with hemolysis were considered “confirmed” cases. Those with passively acquired isoagglutinins but without evidence of hemolysis or with an alternative explanation for anemia were considered “asymptomatic”, and cases without a full hemolytic evaluation but still clinically suspicious were categorized as “suspected” cases. Results: Passively acquired isoagglutinins were detected in 11 patients following 12 separate treatments with IVIG (one patient had antibodies noted after two separate treatment episodes >3 weeks apart). Four of these 12 cases were categorized as “confirmed” cases, five as “suspected” and three as “asymptomatic”. The indication for IVIG use was a neurologic disorder in three of the four confirmed cases, with immune thrombocytopenic purpura (ITP) being the indication in the other case. In suspected cases, ITP was the indication in four of the five cases, with the fifth patient carrying a diagnosis of Kawasaki’s disease. During the 7 month period reviewed, 250 unique patients were treated with IVIG, meaning 1.6% of patients (4/250) had confirmed IVIG-associated hemolytic anemia and another 1.6% (4 patients; 5 events) had suspected hemolytic anemia during this period. The mean decrease in hemoglobin was 4.1 g/dL in confirmed cases (range 1.3–7.1 g/dL) and 2.7 g/dL in suspected cases (range 1.7–4.2 g/dL). Eight of nine patients reviewed had blood type A positive; the other was B positive. The median time from initiation of therapy to hemoglobin nadir was eight days in confirmed and three days in suspected cases. The mean dose of IVIG administered in confirmed cases was 300 g (range 180–400 g) and was 162 g (range 50–300 g) in suspected cases. Red cell transfusion was required in three of the four confirmed cases. Privigen™ was the IVIG product utilized in all four confirmed and the first three suspected cases. After removal of Privigen™ from the Mayo Clinic formulary given concerns regarding these cases, two suspected cases of IVIG-associated hemolytic anemia occurred with Gamunex-C™, including one in a patient who previously suffered confirmed hemolysis after receipt of Privigen™. Conclusions: Hemolytic anemia is a rare complication of therapy with IVIG. The rate of hemolytic anemia following IVIG administration over the evaluated period is consistent with previous reports, but it should be noted that these cases were detected without the aid of an active surveillance policy, indicating the actual rate of hemolytic anemia associated with IVIG use was likely greater than that detected by this review. Our series suggests that those with blood type A may be at increased risk for this complication; further work is ongoing to better define risk factors for development of this potentially significant complication of IVIG therapy. Disclosures: Off Label Use: IVIG use in various off-label indications.

Abstract Abstract 1241 Background: Hospitalization (with or without surgery) is a major risk factor for incident venous thromboembolism (VTE); however, the contribution of interim hospitalization to risk of recurrent VTE is unknown. Objective: To estimate risk of recurrent VTE related to interim hospitalization by conducting a population-based longitudinal review of provider-linked detailed medical records. Methods: We performed a nested case-cohort study. The cohort consisted of all Olmsted County residents with incident VTE 1988–2000 and ≥1 day follow-up. Cases were cohort members with recurrent VTE. Subjects were followed for all interim hospitalizations and warfarin use from incident VTE until earliest of emigration, death, recurrent VTE, or 12/31/2005. Data were analyzed using Cox proportional hazards and time dependent covariates to test for the effects of interim hospitalization and prophylaxis on VTE recurrence, adjusting for gender and age at incident VTE. Analyses were limited to subjects who survived free of death and recurrent VTE for ≥ 6 months. Results: Of 1262 incident VTE events (cohort), there were 309 VTE recurrences (cases). We randomly sampled 272 subjects from the cohort and 163 cases. Of the random samples, 210 incident events and 83 cases survived ≥ 6 months free of death and recurrent VTE and form our analysis population. The rate of secondary (interim) prophylaxis was approximately 50% for both incident events and cases, and was not predictive of recurrence (p=0.73). Male gender and interim hospitalization were associated with increased VTE recurrence even after adjusting for age at incident VTE and use of secondary warfarin prophylaxis. The hazard of recurrent VTE was nearly 10-fold higher for subjects with interim hospitalization versus those with none (HR: 9.6; 95% CI: 6.6, 13.8); men had a 1.5-fold increased recurrence rate compared with women (HR: 1.5; 95% CI: 1.1, 2.1). Conclusions: Our results, for the first time, show the importance of interim hospitalization as a predictor of VTE recurrence. Disclosures: No relevant conflicts of interest to declare.

AbstractBackgroundCancer‐associated venous thromboembolism (VTE) carries a high rate of recurrence and death. Guidelines recommend continued anticoagulation therapy as long as active cancer persists. Apixaban 2.5 mg twice daily is the FDA‐approved dose for secondary prevention regardless of VTE causation. Whether this apixaban dose is appropriate for secondary VTE prevention in cancer patients is not clear. The rationale and design of this investigator initiated phase III, multicenter, randomized, double‐blind, trial assessing apixaban 2.5 mg vs 5 mg twice daily for 12 months for the secondary VTE prevention in cancer patients (n = 370) who have completed 6 months (but no more than 12 months) of anticoagulation is provided (NCT03080883).Methods/DesignThe primary study objective is to estimate differences in the combined rate of major plus clinically relevant non‐major bleeding for apixaban 2.5 mg vs 5 mg twice daily. Secondary efficacy outcome is to assess rates of venous or arterial thromboembolism. Participating centers are chosen from the Academic and Community Cancer Research United (ACCRU) consortium.ConclusionWe anticipate these trial results to provide evidence supporting low‐dose apixaban as a safe agent for secondary prevention of cancer‐associated VTE for patients who have already completed 6‐12 months of anticoagulation.

Abstract Background Recurrent VTE is frequent and may be fatal; the 2-week case fatality rate after recurrent pulmonary embolism is 11%. However, predictors of VTE recurrence remain uncertain. Objective To identify independent predictors of VTE recurrence, including interim exposures, adjusted for baseline characteristics and treatments. Methods Using the resources of the Rochester Epidemiology Project, we identified all Olmsted County, MN residents with objectively-diagnosed incident VTE over the 13-year period, 1988-2000. All patients surviving ≥1 day were followed forward in time for first objectively-diagnosed VTE recurrence, death or other loss to follow-up, or 12/31/2005, whichever came first. VTE recurrence was defined as new thrombosis of a previously uninvolved venous territory or re-thrombosis of a previously involved venous territory after interim clearing of the incident thrombosis. We estimated the cumulative incidence of VTE recurrence using the Kaplan Meier product limit method, both overall and by incident cancer-associated, idiopathic and non-cancer secondary VTE. For all patients with VTE recurrence, and a random sample of all patients with incident VTE, we reviewed the complete medical records in the community and collected demographic and baseline characteristics, treatments (heparin and warfarin [including proportion of time in therapeutic range], IVC filter, aspirin, statins) and interim VTE risk factor exposures. Using a case-cohort study design with Barlow’s weighting scheme, we tested these demographic, baseline and interim characteristics as potential predictors of VTE recurrence using time-dependent Cox proportional hazards modeling. Results Among 1261 incident VTE patients who survived ≥1 day, 306 developed recurrent VTE over 6,485 person-years of follow-up. The cumulative incidence of VTE recurrence at 30 and 180 days, and 1 and 5 years, were 4.5%, 8.2%, 10.5% and 20.3%, respectively. The five-year cumulative recurrence rates among patients with incident cancer-associated, idiopathic and non-cancer secondary VTE were 42.6%, 26.8% and 18.5%, respectively. Among the random cohort of 415 incident VTE cases, 381 (92%) and 359 (87%) received heparin and warfarin therapy for a median (IQR) 5 (4 - 7) and 119 (63 - 194) days, respectively. From multivariable analysis, interim exposure to trauma, major surgery (general, cardiac or gynecologic), infection, hospitalization for acute medical illness or active cancer after the incident VTE were each associated with an increased hazard of VTE recurrence, while use of warfarin and achievement of a therapeutic APTT within the first day of starting heparin were associated with reduced hazards. Although measures of time in therapeutic range while on heparin or warfarin were associated with a reduced risk of recurrence from univariate analyses, these results were not significant when adjusting for other risk factors. Conclusions Among patients with incident VTE, new exposure to trauma, major surgery, infection, hospitalization for acute medical illness or active cancer are independent predictors of VTE recurrence; patients with such exposures should be considered for VTE prophylaxis. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 476 Background: The burden of VTE among nursing home (NH) residents is known to be high. Yet very little data exist to help determine which NH residents to target for VTE prophylaxis. The need to characterize VTE risk in this population is especially great because the advanced age and high comorbidity that typify NH residents contribute to increased likelihood of adverse consequences from VTE prophylaxis. To compound the problem, results of our prior univariate analyses of certain factors known to contribute substantially to VTE risk in the general population (e.g., major surgery, medical hospitalization, trauma) suggest that impact of these factors on VTE may be less substantial among NH residents. Objective: To use the longitudinal population-based resources of the Rochester Epidemiology Project (REP) to investigate the contribution of multiple clinical characteristics to risk of VTE among NH residents. Methods: We took advantage of the previous identification of all Olmsted County, MN residents who met research criteria for incident VTE 1988 through 2005 (N=2,332). We then determined which individuals were resident of a local NH at time of VTE symptom onset, regardless of location of symptom onset (i.e., individuals whose VTE occurred in-hospital having been admitted from a NH were considered NH residents). For each such NH VTE case (N=269), we identified 2 same sex Olmsted County residents of similar age and duration of medical history who were also resident of a local NH at the time of the case's VTE event (i.e., index date) (N=538). We reviewed the detailed provider-linked medical records of NH VTE cases and NH non-VTE controls for 3 months before index for information on multiple characteristics identified or hypothesized as contributing to VTE risk in studies of the general population and other at-risk subgroups by our group and others (e.g., patient demographics, body mass index, major surgery, hospitalization for acute medical illness, outpatient surgical procedures, trauma/fracture, leg paresis, active cancer, superficial vein thrombosis, varicose veins, infections, diabetes mellitus, coronary artery disease, congestive heart failure, and multiple medications, including anticoagulants, statins, beta-blockers, ACE inhibitors and angiotensin II receptor antagonists). We tested and estimated the odds ratio associated with each factor using step-wise conditional logistic regression. Variables for which <10 cases or <10 controls exhibited the characteristic were excluded from analysis. Results: The first five variables to enter the model were urinary tract infection, active cancer, superficial vein thrombosis, pneumonia, and leg paresis. The respective odds ratios (95% confidence intervals) with all five in the model were 1.7 (1.2, 2.4); 2.1 (1.3, 3.5); 2.1 (1.3, 3.4); 1.9 (1.3, 2.8); 2.3 (1.3, 4.2); each p value was <0.01. Variables associated with high VTE risk in the general population (i.e., surgery, hospitalization for medical illness, trauma/fracture) were not included in the top five risk factors for NH residents. Conclusions: Infection is a potent VTE risk factor among NH residents. Our study results will help inform development of practice guidelines in the NH and stimulate future research on putative VTE mechanisms. REP data afford limited information on cognitive and physical disability, immobility, and need for NH care. Additional investigations are needed that combine information from clinical and NH assessments. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 5118 Background: Increased factor VIII:C (FVIII:C) and hypofibrinolysis are VTE risk factors, and beta-blockers and angiotensin converting enzyme (ACE) inhibitors reduce FVIII:C and enhance fibrinolysis, respectively. Objective: To test the hypotheses that beta-blockers and ACE inhibitors reduce VTE risk. Methods: Using longitudinal, population-based Rochester Epidemiology Project resources, we identified all Olmsted County, MN residents with objectively-diagnosed incident VTE over the 13-year period, 1988–2000 (n=1306), and one to two Olmsted County residents per case matched on age, event year and duration of prior medical history (n=1500). For cases and controls, we reviewed their complete medical history in the community for previously-identified VTE risk factors (e.g., hospitalization with or without surgery, nursing home confinement, trauma/fracture, leg paresis, active cancer, superficial vein thrombosis and varicose veins), as well as body mass index (BMI), coronary artery disease (CAD), congestive heart failure (CHF), and the use of statins, beta-blockers, ACE inhibitors and angiotensin II receptor antagonist drugs. Using conditional logistic regression, we tested beta-blockers and ACE inhibitors/angiotensin II receptor antagonists for an association with VTE, both individually and after adjusting for age, BMI, previously-identified VTE risk factors, CAD, CHF and the use of statins. Results: Among cases and controls respectively, 191 and 173 received beta-blockers, and 171 and 154 received ACE inhibitors/angiotensin II receptor antagonists. Univariately, both beta-blockers (unadjusted OR=1.31; p=0.02) and ACE inhibitors/angiotensin II receptor antagonists (unadjusted OR=1.32; p=0.02) were modestly associated with increased VTE risk. However, after controlling for age, BMI, previously-identified VTE risk factors, CAD, CHF and the use of statins, beta-blockers (OR=1.06; 95% CI: 0.74, 1.51; p=0.75) and ACE inhibitors/angiotensin II receptor antagonists (OR=0.94; 95% CI: 0.65, 1.37; p=0.75) were no longer associated with VTE. Conclusions: Beta-blockers and ACE inhibitors/angiotensin II receptor antagonists do not appear to be protective against VTE. Disclosures: No relevant conflicts of interest to declare.

Abstract Background Tunneled central venous catheters have traditionally been used for administration of chemotherapy (chemo) for acute leukemia treatment. Peripherally inserted central catheters (PICC) are increasingly being used, but there is an increased risk of PICC-associated thrombosis (PAT). There is limited information on management of PAT in this subgroup of patients (pt). Methods In this retrospective cohort study we investigated the primary management of PICC related upper extremity venous thrombosis (TB) in pt with hematologic malignancy undergoing chemo at Mayo Clinic Rochester. Eligible pt were 18 years and older, had documentation of PICC placement at our institution, initiation of chemo within a week of PICC placement, and the TB was objectively documented by compression venous ultrasound (CVU). Superficial venous TB (SVT) was defined as TB of subcutaneous veins (basilic and cephalic) and deep venous TB (DVT) defined as TB of brachial, axillary, subclavian, or innominate superior vena cava and internal jugular veins. We retrospectively stratified initial management (IM) into 1) PICC removal alone (PR), 2) PR and therapeutic anticoagulation (AC), 3) AC alone, and 4) conservative management (CM) consisting of symptomatic care and observation. We also investigated factors influencing IM of PAT. Long term outcomes including incidence of pulmonary embolism (PE), post phlebitic syndrome and recurrence of TB were noted. Results Between 2006 and 2012, 190 pt with AML (n=160), MDS or MDS/MF (n=10), or ALL (n=20) met our study criteria. Overall, 40/190 (21.6%) developed PAT: AML n=38, ALL n=1, MDS/MF n=1. SVT occurred in 16/40 (40%) pt and DVT occurred in 24/40 (60%) pt. IM is shown in Table 1. One pt with SVT received AC for 6 weeks as well as PR. In this pt, IM included AC because of proximity of TB to deep veins. 7 pt had a follow up (f/u) CVU within 3 months demonstrating: TB progression (prog, n=1, IM with PR alone but with prog AC was started); TB stability (stab, n=2, both IM with PR alone) and TB resolution/improvement (R/I, n= 4, 2 IM with PR and 2 IM with CM) In the 5 pt with CM, 2 pt had f/u CVU demonstrating improvement, one pt had charted clinical improvement , and 2 pt had no charted clinical f/u. Of DVT pt on AC (n=14), 5 pt completed at least 2 months of AC. Reasons for early cessation (n=9) of AC included thrombocytopenia (tcp, n=4), hematoma (n=1), hematuria (n=1), subarachnoid hemorrhage (n=1), and unknown (n=1). One pt died 2 days after presence of DVT was noted. Two pt initially treated with PR alone developed a second TB with placement of a new PICC on contralateral arm and AC was subsequently initiated (duration: 3 months (n=1), and 8 days (n=1)). 14 pt with DVT had f/u CVU within 3 months which demonstrated prog (n=2), stab (n= 8), or R/I ( n=4) of TB (Table 2). The 2 pt with TB prog subsequently received longer term AC guided by platelet count. In 5 pt with PICC not initially removed, 3 pt had PR after completion of chemo. (1-4 days), one pt had PR at discharge (27 days from TB), and one pt had PICC in place on discharge. One pt with DVT experienced a PE within one year f/u. This pt had initially completed 3 days of AC which was stopped because of tcp. Conclusion In this cohort of patients with PAT, the most common IM consisted of PR, which appeared to result in a low recurrence rate among pt with SVT. In pt with DVT, the role of AC remains to be defined given the abbreviated course of AC in most pt. Though, the lack of CVU followup in all pt limits conclusions, there appeared to be a low rate of symptomatic prog. Initiation of AC was largely guided by platelet count and degree of occlusive symptoms. Thrombocytopenia was also the most commonly cited reason for discontinuing AC. Close clinical follow up aided by the use of CVU was integral to ensure that PAT did not lead to further adverse events. Disclosures: No relevant conflicts of interest to declare.