Diagnosing, Ruling Out and Managing Vaccine-induced Immune Thrombotic Thrombocytopenia (VITT)/Vaccine-Induced Prothrombotic Immune Thrombocytopenia (VIPIT)

Does the patient exhibit one or more of the following symptoms:

{{value}} ? ? ? ? ? ?

Has the patient received their COVID-19 vaccine between 4 and 28 days ago?

Yes No

Does the patient’s complete blood count (CBC) show a platelet count <150 x 10⁹/L?

^*Draw a complete blood count (CBC) and/or send the patient to the nearest emergency department.

Yes No

Does the patient’s tests show the following results?

^*Perform additional tests with the patient.

D-dimer: Elevated
Blood film: Normal (apart from low platelets)
Imaging based on clinical suspicion confirms venous or arterial thrombosis

^**Not all cases of VITT initially present with a clot. A confirmed blood clot is not required to make a presumptive diagnosis of VITT^**

Yes No

RECOMMENDATION

VIPIT/VITT unlikely. Do not proceed to HIT testing.

Pai M, Grill A, Ivers N, et al. Vaccine-induced prothrombotic immune thrombocytopenia VIPIT following AstraZeneca COVID-19 vaccination. Science Briefs of the Ontario COVID-19 Science Advisory Table. 2021;1(17). https://doi.org/10.47326/ocsat.2021.02.17.1.0

RECOMMENDATION

Presumptive diagnosis of VIPIT/VITT. Proceed to hematology for HIT testing. Patients with presumptive and confirmed VIPIT/VITT should be treated similarly to HIT:

No heparin
No platelet transfusions
First line anticoagulants: direct oral anti-Xa inhibitors (e.g., rivaroxaban, apixaban, edoxaban)
Consult hematologist
IVIG 1 g/kg daily for at least 2 days. (Particularly for severe or life-threatening thrombosis.)

Recommended Laboratory Methods:

Antigen-binding assay (ELISA) for PF4/heparin antibodies: ELISA Testing – other tests may produce false negatives

Send for testing before initiation of treatment. Do not wait for test results before initiation of treatment.

NOTE: All suspected adverse events following immunization (AEFI), including thrombosis, and both presumptive and confirmed VIPIT, should be reported using the provincial AEFI form and sent to the local Public Health Unit.

Pai M, Grill A, Ivers N, et al. Vaccine-induced prothrombotic immune thrombocytopenia VIPIT following AstraZeneca COVID-19 vaccination. Science Briefs of the Ontario COVID-19 Science Advisory Table. 2021;1(17). https://doi.org/10.47326/ocsat.2021.02.17.1.0

Thrombophilia Testing Algorithm

Is this the patient’s first VTE?

Yes No

Where is the VTE?

Usual site: arm or leg deep vein thrombosis (DVT), pulmonary embolism (PE) Unusual site: intracranial?abdominal?both arterial and venous?

Is the VTE provoked or unprovoked?

Provoked Unprovoked

Does this patient have strong or weak risk factors for VTE?

Strong risk factors - cancer, surgery, trauma, immobilization, major medical illness, central line, pregnancy, post-partumcancer, local or adjacent infection / inflammation, surgery (includes abdominal vein clot with Caesarean section), cirrhosis, trauma, post-partum Weak Risk Factor – hormones (e.g. OCT, HRT), travel longer than 5 hours, obesity, minor injury (fall), below knee cast or arthroscopyhormones (e.g. OCT, HRT), pregnancy

RECOMMENDATION

Recurrent VTE

Consider specialist consultation and thrombophilia testing for patients with at least one of:

<50 years old
Strong family history (first-degree family members affected at <50 years old)
At least one unprovoked VTE in usual or unusual site

OR two or more provoked VTEs

Thrombophilia testing is NOT required.

Thrombophilia testing* is NOT required for MOST patients.

Consider thrombophilia testing with specialist consultation if 1 or more of:

Consider thrombophilia testing* WITH specialist consultation if 1 or more of:

Concomitant arterial disease
Young age (<50 years old)
Strong family history, i.e. first-degree family members affected at <50 years old
CBC abnormalities (e.g. anemia, thrombocytopenia, thrombocytosis, polycythemia), consider MPN?APS?PNH?HIT?
Autoimmune disease

Consider APS testing, especially in the case of arterial or recurrent events, and/or recurrent pregnancy loss. If abnormal results, repeat testing in 12 weeks, then refer.

Anticoagulants can interfere with many thrombophilia tests. Is your patient on anticoagulants? Click here for more information.

* Only consider thrombophilia testing if the test results will make a difference in how you manage the patient.

Patient Summary
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Where is the VTE?	{{context.site.full_description}}
Is the VTE provoked or unprovoked?	{{context.vte_state.value}}
Does this patient have strong or weak risk factors for VTE?	{{context.risk_factor.full_description}}

Thrombophilia tests* that can be done during anticoagulant therapy:

Factor V Leiden mutation
Prothrombin gene mutation
JAK2 mutation
PNH flow cytometry

Impact of anticoagulants on commonly ordered thrombophilia tests

Thrombophilia tests* that require anticoagulant interruption are shown in the table

Anticoagulant interruption is defined as:

Warfarin interruption for at least 1 week
DOAC interruption for at least 2 days (4 days if patient on dabigatran and has CrCl <50 mL/min)
UFH or LMWH interruption for at least 24 hours

* Only consider thrombophilia testing if the test results will make a difference in how you manage the patient.

Anticoagulant Dosing In Atrial Fibrillation

Age (years) required

Weight (kg) required

Serum Creatinine (µmol/L) required

Congestive Heart Failure History

Hypertension History

Diabetes Mellitus History

Previous stroke or TIA

History of macrovascular disease (coronary, aortic or peripheral)

Patient has another indication for warfarin therapy (for example, mechanical heart valve, LV thrombus, rheumatic valvular heart disease)

Female Patient

Concomitant use of P-gp inhibitors (except amiodarone and verapamil) ?

Perioperative Anticoagulant Management Algorithm

Please select the type of surgery:

Elective

Emergency Surgery/procedure <12 h (e.g. intracranial bleed, ruptured viscus, cardiac tamponade)

Urgent surgery/procedure 12-24 h (e.g. hip fracture repair, acute cholecystitis)

Procedural Bleeding Risk

Low (minor non-dental procedure) ?

Cataract surgery
Dermatologic procedures (e.g. biopsy)
Gastroscopy or colonoscopy without biopsies
Coronary angiography
Permanent pacemaker insertion or internal defibrillator placement (if bridging anticoagulation is not used)
Selected procedures (e.g. thoracentesis, paracentesis, arthrocentesis)

Low (minor dental procedure) ?

Dental extractions (1 or 2 teeth)
Endodontic (root canal) procedure
Subgingival scaling or other cleaning

Moderate ?

Abdominal surgery (e.g. cholecystectomy, hernia repair, colon resection)
Other general surgery (e.g. breast)
Other intrathoracic surgery
Other orthopedic surgery
Other vascular surgery
Non-cataract ophthalmologic surgery
Gastroscopy or colonoscopy with biopsies
Selected procedures (e.g. bone marrow biopsy, lymph node biopsy)
Complex dental procedure (e.g. multiple tooth extractions)

High ?

Any surgery or procedure with neuraxial (spinal or epidural) anesthesia
Neurosurgery (intracranial or spinal)
Cardiac surgery (e.g. CABG, heart valve replacement)
Major vascular surgery (e.g. aortic aneurysm repair, aortofemoral bypass)
Major orthopedic surgery (e.g. hip/knee joint replacement surgery)
Lung resection surgery
Urological surgery (e.g. prostatectomy, bladder tumour resection)
Extensive cancer surgery (e.g. pancreas, liver)
Intestinal anastomosis surgery
Reconstructive plastic surgery
Selected procedures (e.g. kidney biopsy, prostate biopsy, cervical cone biopsy, pericardiocentesis, colonic polypectomy)

Anticoagulant Used

Apixaban Dabigatran Edoxaban Rivaroxaban Warfarin

Anticoagulant Used

Apixaban Dabigatran Edoxaban Rivaroxaban Warfarin

Initial management

Refer for procedural/surgical intervention
Check hemoglobin concentration and platelet count to help guide transfusion
Transfusion therapy
- RBC transfusion for symptomatic anemia
- Platelets for thrombocytopenia (platelets less than 50 x 10⁹/L) or patients on antiplatelet agents
Discontinue anticoagulant

Initial management

Refer for procedural/surgical intervention
Check hemoglobin concentration and platelet count to help guide transfusion
Transfusion therapy
- RBC transfusion for symptomatic anemia
- Platelet transfusion for thrombocytopenia (platelets less than 50 x 10⁹/L) or patients on antiplatelet agents
Discontinue anticoagulant

Creatinine Clearance

Weight

Female patient

Age (years)

Weight (kg)

Serum Creatinine (µmol/L)

INR

Recommendations

If INR ≤ 1.5 → no reversal needed
Proceed to Surgery/Procedure
Consider PCC for very high bleeding risk surgeries/proceedures

Recommendations
Give vitamin K, 10 mg IV

Repeat INR before surgery

If INR ≤ 1.5 → no reversal needed, Proceed to Surgery/Procedure
If INR >1.5, consider PCC

Recommendations

If INR ≤ 1.5 → no reversal needed
Proceed to Surgery/Procedure

Recommendations

Give vitamin K (10 mg in 50 mL normal saline IV STAT) and units of PCC (DO NOT REPEAT IF ALREADY GIVEN) PCC Dosing and Administration:

Infuse PCC intravenously:
- OCTAPLEX^® 1 mL/min followed by maximum 2-3 mL/min (180 mL/hr)
- BERIPLEX^® IV at 1 mL/min followed by maximum 8 mL/min (480 mL/hr)
PCC contraindicated in heparin-induced thrombocytopenia
Inform patients/families regarding small (<2%) thrombotic risk of PCC (e.g. stroke MI, DVT, PE), but consequences of uncontrolled surgical bleeding likely exceed this risk
- If PCC is unavailable or contraindicated transfuse fresh frozen plasma 10-15 mL/kg (approx. 3-4 units for adults)
If INR not reported or weight unknown and cannot delay PCC administration give PCC 2000 units IV and vitamin K 10 mg IV STAT

Repeat INR 15 min after PCC infusion
If INR ≤ 1.5: Warfarin reversed
If INR > 1.5: Consider additional dose of PCC, consider other causes elevated INR (e.g. DIC, dilutional coagulopathy, liver failure)

Lab testing for Residual NOAC Effect

ng/mL

Not available or NOAC effect not known

Recommendations

Proceed to Surgery/Procedure

Recommendations

Reassess anticoagulant effect just before surgery

1. Determine plasma dabigatran concentration using dilute thrombin time/Hemoclot^®assay

If dabigatran level <30 – 50 ng/mL: no reversal
If dTT unavailable use dosing regimen, timing of last dose and creatinine clearance to determine presence of drug

View Half-life of dabigatran View interpretation of coagulation tests

2. If dabigatran level ≥ 30-50 ng/mL, OR dTT unavailable and clinically significant dabigatran levels suspected:

Idarucizumab administered as two 50-mL bolus infusions containing 2.5 g each of idarucizumab (total 5 g) no more than 15 minutes apart

3. If idarucizumab unavailable: alternative therapies (no clinical evidence)

Prothrombin complex concentrate (PCC) (50 units/kg, max 3000 units)
- OCTAPLEX® IV at 1 mL/min followed by maximum 2-3 mL/min (180 mL/hr)
- BERIPLEX® IV at 1 mL followed by maximum 8 mL/min (480 mL/hr)
PCC contraindicated in heparin-induced thrombocytopenia
FEIBA® 2000 units (50 units/kg , max 2000 units)
Inform patients/families regarding small thrombotic risk of PCC and FEIBA® (e.g. stroke MI, DVT, PE), but consequences of delaying the surgery/procedure likely exceed this risk.

4. Adjunctive therapy

Hemodialysis (~65% removal after 4 hrs) if feasible

Disclaimer: These general recommendations do not replace clinical judgement. Physicians must consider relative risks and benefits in each patient in applying these recommendations.

Recommended assays and thresholds for clinically relevant plasma NOAC concentrations are estimates based on available evidence that require further study/validation. The threshold may be higher or lower depending on the assay.

Determine plasma dabigatran concentration using dilute thrombin time (dTT)/Hemoclot^® assay. If dTT unavailable use dosing regimen, timing of last dose and creatinine clearance to determine presence of drug. View Half-life of dabigatran.
Consider idarucizumab (specific dabigatran reversal agent)
- 2.5 grams IV infusion, repeat 2.5 grams IV infusion within 15 minutes
If idarucizumab not available, consider pro-hemostatic therapy (no clinical evidence)
- Prothrombin complex concentrate (PCC) (50 units/kg, max 3000 units)
  - OCTAPLEX^® IV 1 mL/min followed by maximum 2-3 mL/min (180 mL/hr)
  - BERIPLEX^® IV at 1 mL followed by maximum 8 mL/min (480 mL/hr)
- PCC contraindicated in heparin-induced thrombocytopenia
- FEIBA units (50 units/kg , max 2000 units)
- Inform patients/families regarding small thrombotic risk of PCC and FEIBA (e.g. stroke MI, DVT, PE)
Adjunctive therapy
- Hemodialysis (~65% removal after 4 hrs) if feasible

Determine presence of apixaban using apixaban-calibrated anti-Xa activity assay. If apixaban-calibrated anti-Xa activity assay unavailable use dosing regimen, timing of last dose and creatinine clearance to determine presence of drug. View Half-life of apixaban.
Consider pro-hemostatic therapy (no clinical evidence)
- Prothrombin complex concentrate (PCC) (50 units/kg, max 3000 units)
  - OCTAPLEX^® IV 1 mL/min followed by maximum 2-3 mL/min (180 mL/hr)
  - BERIPLEX^® IV at 1 mL followed by maximum 8 mL/min (480 mL/hr)
- PCC contraindicated in heparin-induced thrombocytopenia
- FEIBA units (50 units/kg , max 2000 units)
- Inform patients/families regarding small thrombotic risk of PCC and FEIBA (e.g. stroke MI, DVT, PE)

Determine presence of rivaroxaban using rivaroxaban-calibrated anti-Xa activity assay. If rivaroxaban-calibrated anti-Xa activity assay unavailable use dosing regimen, timing of last dose and creatinine clearance to determine presence of drug. View Half-life of rivaroxaban.
Consider pro-hemostatic therapy (no clinical evidence)
- Prothrombin complex concentrate (PCC) (50 units/kg, max 3000 units)
  - OCTAPLEX^® IV 1 mL/min followed by maximum 2-3 mL/min (180 mL/hr)
  - BERIPLEX^® IV at 1 mL followed by maximum 8 mL/min (480 mL/hr)
- PCC contraindicated in heparin-induced thrombocytopenia
- FEIBA units (50 units/kg , max 2000 units)
- Inform patients/families regarding small thrombotic risk of PCC and FEIBA (e.g. stroke MI, DVT, PE)

Determine presence of edoxaban using edoxaban-calibrated anti-Xa activity assay. If edoxaban-calibrated anti-Xa activity assay unavailable use dosing regimen, timing of last dose and creatinine clearance to determine presence of drug. View Half-life of edoxaban.
Consider pro-hemostatic therapy (no clinical evidence)
- Prothrombin complex concentrate (PCC) (50 units/kg, max 3000 units)
  - OCTAPLEX^® IV 1 mL/min followed by maximum 2-3 mL/min (180 mL/hr)
  - BERIPLEX^® IV at 1 mL followed by maximum 8 mL/min (480 mL/hr)
- PCC contraindicated in heparin-induced thrombocytopenia
- FEIBA units (50 units/kg , max 2000 units)
- Inform patients/families regarding small thrombotic risk of PCC and FEIBA (e.g. stroke MI, DVT, PE)

Indication For Antithrombotic

Atrial Fibrillation DVT/PE Mechanical Valve

Thromboembolic Risk (Atrial Fibrillation)

High

CHADS is 5 - 6, or
stroke/TIA within 3 months, or
rheumatic mitral stenosis

Moderate

CHADS is 3 - 4

Low

CHADS is 0 - 2

Thromboembolic Risk (DVT/PE)

High

DVT/PE within 3 months, or
Known severe thrombophilia*

Moderate

VTE within 3-12 months, or
Recurrent VTE, or
Active cancer

Low

Single VTE > 12 months prior

Thromboembolic Risk (Mechanical Valves)

High

Any mitral valve prothesis, or
Caged ball or tilting disc aortic prosthesis, or
stroke/TIA within 6 months

Moderate

Bileaflet aortic valve with either atrial fibrillation or CHADS score >= 1

Low

Bileaflet aortic valve without atrial fibrillation and CHADS score = 0

Summary

Preoperative Recommendations

Postoperative Recommendations

Click here for a sample of a perioperative bridging protocol.

Schedule

Day	Instructions

Pulmonary Embolism Management

Atrial Fibrillation

Bleed Management

Deep Vein Thrombosis

DOAC Follow-up

CHADS2 Score for Atrial Fibrillation Stroke Risk

Estimates stroke risk in patients with atrial fibrillation by the CHADS2 criteria.

Congestive Heart Failure history?

Hypertension history?

Age ≥ 75?

Diabetes Mellitus history?

Previous stroke or TIA?

CHA2DS2-VASc Score for Atrial Fibrillation Stroke Risk

Calculates stroke risk for patients with atrial fibrillation, possibly better than the CHADS2 score.

Age

< 65 (+0) 65-74 (+1) ≥ 75 (+2)

Congestive Heart Failure History (+1)

Hypertension History (+1)

Stroke/TIA/Thromboembolism History (+2)

Vascular Disease History? (previous MI, peripheral arterial disease or aortic plaque) (+1 )

Diabetes Mellitus (+1)

Female Patient (+1)

Creatinine Clearance (Cockcroft-Gault Equation)

Calculates creatinine clearance according to the Cockgroft-Gault equation.

Female patient

Age (years)

Weight (kg)

Serum Creatinine (µmol/L)

HAS-BLED Score for Major Bleeding Risk

Estimates risk of major bleeding for patients on anticoagulation to help determine risk-benefit in atrial fibrillation care.

Hypertension History (uncontrolled, >160 mmHg systolic)

Renal Disease (Dialysis, transpant, Cr > 2.6 mg/dl or > 200 µmol/L)

Liver Disease (Cirrhosis, Bilirubin > 2x Normal, AST/ALT/AP > 3x Normal)

Stroke History

Prior Major Bleeding or Predisposition to Bleeding

Labile INR (Unstable/high INRs)

Age ≥ 65

Medication Usage Predisposing to Bleeding (Antiplatelet agents, NSAIDS)

Alcohol Usage History

ABCD2 Score for TIA

Estimates risk of stroke after a TIA, according to patient risk factors.

Age ≥ 60

BP ≥ 140/90 mmHg at initial evaluation

Clinical Features of the TIA

Unilateral Weakness Speech Disturbance Without Weakness Other Symptom

Duration of Symptoms

< 10 minutes 10-59 minutes ≥ 60 minutes

Diabetes Mellitus in Patient's History

Wells' Criteria for DVT

Calculates Wells' Score for risk of DVT.

Active cancer?

Bedridden recently > 3 days or major surgery within four weeks?

Calf swelling > 3cm compared to the other leg?

Collateral (nonvaricose) superficial veins present?

Entire leg swollen?

Localized tenderness along the deep venous system?

Pitting edema, greater in the symptomatic leg?

Paralysis, paresis, or recent plaster immobilization of the lower extremety

Previously documented DVT?

Alternative diagnosis to DVT as likely or more likely?

Wells' Criteria for Pulmonary Embolism / PE

Calculates Wells' Score for risk of PE.

Clinical Signs and Symptoms of DVT

PE Is #1 Diagnosis, or Equally Likely

Heart Rate > 100

Immobilization at least 3 days, or Surgery in the Previous 4 weeks

Previous, objectively diagnosed PE or DVT

Hemoptysis

Malignancy w/ Treatment within 6 mo, or palliative

PERC Rule for Pulmonary Embolism

Shows the PERC criteria, which can rule out PE if all criteria are present and pre-test probability is ≤15%.

Age < 50

HR < 100

O2 Sat on Room Air >94%

No Prior History of DVT/PE

No Recent Trauma or Surgery

No Hemoptysis

No Exogenous Estrogen

No Clinical Signs Suggesting DVT

TIMI Risk Score for UA/NSTEMI

Estimates mortality for patients with unstable angina and non-ST elevation MI.

Age ≥ 65 years

≥ 3 Risk Factors for CAD

Known CAD (stenosis ≥ 50%)

ASA Use in Past 7d

Severe angina (≥ 2 episodes w/in 24 hrs)

ST changes ≥ 0.5mm

+ Cardiac Marker

TIMI Risk Score for STEMI

Estimates mortality in patients with STEMI.

Age

< 65 65-74 ≥ 75

DM or HTN or Angina

SBP < 100 mmHg

HR > 100 bpm

Killip Class II-IV

Weight < 67 kg (147.7 lbs)

Anterior ST Elevation or LBBB

Time to Treatment > 4 hrs

Pulmonary Embolism Severity Index (PESI)

Predicts 30-day outcome of patients with pulmonary embolism using 11 clinical criteria.

Age (years) (+1 per year) required

Male Patient (+10)

History of Cancer (+30)

History of heart failure (+10)

History of chronic lung disease (+10)

Heart Rate ≥ 110 (+20)

Systolic Blood Pressure < 100 mmHg (+30)

Respiratory Rate ≥ 30/min (+20)

Temperature < 36° C (96.8° F) (+20)

Altered Mental Status (disorientation, lethargy, stupor, or coma) (+60)

O₂ Saturation < 90% on Room Air (+20)

Simplified PESI (Pulmonary Embolism Severity Index)

Predicts 30-day outcome of patients with pulmonary embolism with fewer criteria than the original Pulmonary Embolism Severity Index.

Patient Age > 80 (years) (+1)

History of Cancer (+1)

History of Chronic Cardiopulmonary Disease (+1)

Heart Rate ≥ 110 (+1)

Systolic Blood Pressure < 100 mmHg (+1)

O₂ Saturation < 90% on Room Air (+1)

Patient Has None of These

	INR 1.6-1.9	INR 2.0-2.9	INR 3.0-5.0	INR > 5.0
Wt < 100 kg	500 units	1000 units	2000 units	3000 units (maximum)
Wt ≥ 100 kg	1000 units	1500 units	2500 units	3000 units (maximum)

Apixaban (Eliquis^®)**
Test	Characteristics	Normal	Abnormal
Calibrated anti-Xa	Accurate, reliable	<30-50 ng/mL Likely no significant anticoagulant effect.*	≥30-50 ng/mL Likely significant anticoagulant effect*
PT/INR	Poor sensitivity	Does not exclude anticoagulant effect.	May indicate anticoagulant effect. Rule out other causes of abnormal PT/INR (e.g. DIC, coagulopathy of liver disease, vitamin K deficiency, warfarin).
aPTT	Poor sensitivity	Does not exclude anticoagulant effect.	May indicate anticoagulant effect. Rule out other causes of abnormal aPTT (e.g. coagulopathy of liver disease, direct thrombin inhibitor, coagulation factor deficiency)

Apixaban (Eliquis^®)**
Test	Characteristics	Normal	Abnormal
Calibrated anti-Xa	Accurate, reliable	<30-50 ng/mL Likely no significant anticoagulant effect.*	≥30-50 ng/mL Likely significant anticoagulant effect*
PT/INR	Poor sensitivity	Does not exclude anticoagulant effect.	May indicate anticoagulant effect. Rule out other causes of abnormal PT/INR (e.g. DIC, coagulopathy of liver disease, vitamin K deficiency, warfarin).
aPTT	Poor sensitivity	Does not exclude anticoagulant effect.	May indicate anticoagulant effect. Rule out other causes of abnormal aPTT (e.g. coagulopathy of liver disease, direct thrombin inhibitor, coagulation factor deficiency)

Dabigatran (Pradaxa^®)**
Test	Characteristics	Normal	Abnormal
Dilute TCT (Hemoclot^®) ECA ECT	Accurate, reliable	<30-50 ng/mL Likely no significant anticoagulant effect.*	≥30-50 ng/mL Likely significant anticoagulant effect.*
TCT	Very sensitive	Likely no significant anticoagulant effect.	Anticoagulant effect present
aPTT	Moderate sensitivity, high variability	May not exclude significant anticoagulant effect.	Anticoagulant effect present
PT/INR	Poor sensitivity, high variability	Does not exclude anticoagulant effect.	May indicate anticoagulant effect. Rule out other causes of abnormal PT/INR (e.g. DIC, coagulopathy of liver disease, vitamin K deficiency, warfarin).

Rivaroxaban (Xarelto^®)**
Test	Characteristics	Normal	Abnormal
Calibrated anti-Xa	Accurate, reliable	<30-50 ng/mL Likely no significant anticoagulant effect.*	≥30-50 ng/mL Likely significant anticoagulant effect.*
PT/INR	Moderate sensitivity, high variability	Does not exclude anticoagulant effect.	Anticoagulant effect present.
aPTT	Poor sensitivity, high variability	Does not exclude anticoagulant effect.	May indicate anticoagulant effect. Rule out other causes of abnormal aPTT (e.g. coagulopathy of liver disease, direct thrombin inhibitor, coagulation factor deficiency).

Day	Warfarin	LMWH
-6	✔	X
-5	X	X
-4	X	X
-3	X	✔
-2	X	✔
-1	X	✔ *
Surgery	X	X
+1	✔	✔ **
+2	✔	✔ **
+3	✔	✔ ***

Dabigatran (Pradaxa^®)
Renal Function	Half-life*
Normal to Mild Impairment (CrCl ≥ 50 mL/min)	7 – 17 hrs
Moderate Impairment (CrCl 30 to 49 mL/min)	17 - 20 hrs
Severe Impairment (CrCl < 30 mL/min)	21 - 35 hrs
Dosing regimens	150 mg bid, 110 mg bid, 220 mg daily, 150 mg daily, 110 mg daily, 75 mg daily

Apixaban (Eliquis^®)
Renal Function	Half-life*
Normal to Mild Impairment (CrCl ≥ 50 mL/min)	8 – 12 hrs
Moderate Impairment (CrCl 30 to 49 mL/min)	8 - 12 hrs
Severe Impairment (CrCl < 30 mL/min)	12 - 17 hrs
Dosing regimens	10 mg bid, 5 mg bid, 2.5 mg bid

Rivaroxaban (Xarelto^®)
Renal Function	Half-life*
Normal to Mild Impairment (CrCl ≥ 50 mL/min)	7 - 11 hrs
Moderate Impairment (CrCl 30 to 49 mL/min)	7 - 11 hrs
Severe Impairment (CrCl < 30 mL/min)	11 - 15 hrs
Dosing regimens	15 mg bid, 20 mg daily, 15 mg daily, 10 mg daily

Diagnosing, Ruling Out and Managing Vaccine-induced Immune Thrombotic Thrombocytopenia (VITT)/Vaccine-Induced Prothrombotic Immune Thrombocytopenia (VIPIT)

Does the patient exhibit one or more of the following symptoms:

Has the patient received their COVID-19 vaccine between 4 and 28 days ago?

Does the patient’s complete blood count (CBC) show a platelet count <150 x 109/L?

Does the patient’s tests show the following results?

RECOMMENDATION

RECOMMENDATION

Thrombophilia Testing Algorithm

Is this the patient’s first VTE?

Where is the VTE?

Is the VTE provoked or unprovoked?

Does this patient have strong or weak risk factors for VTE?

RECOMMENDATION

Recurrent VTE

Anticoagulant Dosing In Atrial Fibrillation

Perioperative Anticoagulant Management Algorithm

Please select the type of surgery:

Procedural Bleeding Risk

Anticoagulant Used

Anticoagulant Used

Initial management

Initial management

Creatinine Clearance

Weight

Lab testing for Residual NOAC Effect

Indication For Antithrombotic

Thromboembolic Risk (Atrial Fibrillation)

Thromboembolic Risk (DVT/PE)

Thromboembolic Risk (Mechanical Valves)

Summary

Preoperative Recommendations

Postoperative Recommendations

Schedule

Pulmonary Embolism Management

Atrial Fibrillation

Bleed Management

Deep Vein Thrombosis

DOAC Follow-up

CHADS2 Score for Atrial Fibrillation Stroke Risk

CHA2DS2-VASc Score for Atrial Fibrillation Stroke Risk

Creatinine Clearance (Cockcroft-Gault Equation)

HAS-BLED Score for Major Bleeding Risk

ABCD2 Score for TIA

Wells' Criteria for DVT

Wells' Criteria for Pulmonary Embolism / PE

PERC Rule for Pulmonary Embolism

TIMI Risk Score for UA/NSTEMI

TIMI Risk Score for STEMI

Pulmonary Embolism Severity Index (PESI)

Simplified PESI (Pulmonary Embolism Severity Index)

Sample Bridging Protocol

PCC dosing (based on weight and INR)

Does the patient’s complete blood count (CBC) show a platelet count <150 x 10⁹/L?