Antithrombotic Therapy in COVID-19 – A Scientific Position Statement by Heart Disease Management Program, National Health Mission, Government of Tamil Nadu
Although there is continuous update in treatment strategies for covid 19, antithrombotic management was observed to be a successful drug treatment of COVID-19. Justin Paul Gnanaraj and colleagues published a guide in the Journal of The Association of Physicians of India under the title “Antithrombotic Therapy in COVID-19 – A Scientific Position Statement by Heart Disease Management Program, National Health Mission, Government of Tamil Nadu”. The summary of this guide is given below:
To provide a brief summary of the need and means of anticoagulation therapy in COVID-19.
The information in this paper is supported with available evidence on anticoagulation therapy and experience and knowledge of various medical expertise.
A) Anticoagulation Therapy
Unless there is any contraindication, intermediate-dose anticoagulation is recommended as it was found to be helpful in preventing the increased risk of venous thromboembolism (VTE) in patients hospitalized with COVID-19.
1) Risk Scoring and anticoagulation
Experts recommend the use of risk scoring to decide on the intensity and duration of anticoagulation therapy
• Assessment of VTE risk- PAUDA model is recommended to assess the risk. An individual with a total score of ≥ 4 is supposed to be at high risk for VTE.
• Assessment of bleeding risk- the use of HAS-BLED score is suggested to assess bleeding risk at baseline before initiating anticoagulant therapy. A patient with a score of 0 or 1 is considered at low risk, more than 3 is considered as high risk for bleed.
• Scoring for DIC risk- the use of ISTH-DIC is recommended in ICU patients. The risk of death due to thrombotic events increases with an Elevated ISTH-SIC score of ≥5.
2) Anticoagulants used in COVID-19
Unfractionated heparin (UFH), low molecular weight heparin (LMWH), and fondaparinux are the parenteral anticoagulants available. While there are concerns attach to unfractionated heparin use, LMWH is the preferred anticoagulant in Covid 19. UFH is appropriate in obstetric patients expecting delivery within 24 hours.
Dose modification in renal failure
• UFH: Preferred anticoagulant with creatinine clearance < 30 ml / min
• Enoxaparin: 1 mg / kg once a day with creatinine clearance between 15-30 ml/min.
• Fondaparinux: 1.5 mg SC once a day with creatinine clearance 20-50 ml/min
Anticoagulants: Directly acting oral anticoagulants [DOACS] are often preferred as compared to Vitamin K antagonists (VKA) and Heparins. Be cautious while choosing to use anticoagulation with a platelet count of less than 50,000 per microliter.
3) Anticoagulation therapy recommendation for COVID-19 patients.
• No anticoagulation is needed in the ambulant COVID-19 patients with or without constitutional/respiratory symptoms, patients with mild or moderate COVID, and high bleeding risk. Individualized treatment should be administered for abnormal PT/ aPTT patients.
• A prophylactic anticoagulation dose can be given to
a) Individuals hospitalized with mild COVID-19, with evidence of lung involvement, without high bleeding risk.
b) Patients hospitalized with moderate COVID-19 with low VTE risk and low bleeding risk
c) Patients with severe COVID-19 with high bleeding risk and low VTE risk / low ISTH- DIC score
• The intermediate anticoagulation dose can be given to hospitalized moderate COVID-19 patients with high VTE risk and low bleeding risk and hospitalized severe COVID -19 patients with low VTE / low ISTH-DIC score and low bleeding risk.
• The therapeutic anticoagulation dose can be given to patients with documented thrombotic events, patients with high suspicion of thrombotic events with the unavailability of imaging, patients with pre-existing clinical indications for therapeutic anticoagulation, patients receiving RRT or those on ECMO, patients with severe COVID-19 with low bleeding risk and high-risk features / high ISTH- DIC score.
• Thrombolytic therapy for Pulmonary embolism should be started with half-dose due to the high risk of bleed in COVID-19 patients and a full course should be completed only if the half dose is not good. Hemodynamically unstable patients should receive reperfusion therapy.
• Mechanical thromboprophylaxis is encouraged in patients with definite indications for anticoagulant therapy, but with contraindications for anticoagulation.
4) Extended anticoagulation for COVID-19 patients post-discharge
Post-discharge anticoagulation is recommended only if:
• Patients were already on anticoagulation before COVID-19 hospitalization
• 3 months anticoagulation therapy for patients with documented VTE
• Patients who were discharged home due to unavailability of bed need prophylactic anticoagulation
• 6-week anticoagulation therapy for patients with no documented VTE, but at high VTE risk and with low bleeding risk.
• 2 weeks anticoagulation therapy for patients with no documented VTE, but with high VTE and bleeding risk.
B) Antiplatelet Therapy
Experts still find a need for larger data to confirm if antiplatelets have a role in thromboprophylaxis for COVID-19 patients.
C) Anticoagulation in Special Situations
Prosthetic Heart Valves- VKAs with frequent INR and clinical monitoring are recommended in all patients with mechanical prosthetic heart valves, including those who are pregnant.
Atrial Fibrillation- with close monitoring to prevent drug interaction, DOACs can be continued in mild COVID patients who are already on DOACS for AF. Heparin can be administered in hospitalized COVID-19 patients with AF and new-onset AF patients are accounted for long-term anticoagulation, guided by CHA2 DS2- Vasc Score. At discharge, chronic AF patients are switched back to the prehospitalization anticoagulation therapy.
Pregnancy and Postpartum- continue anticoagulation during COVID-19 if there were any pre-existing clinical conditions already. DOACS are found to be unsafe during pregnancy. All COVID-19 patients should be continued with anticoagulant therapy for 4-6 weeks postpartum and for at least three months in those with documented VTE.
Thrombocytopenia- Anticoagulation therapy is found to be unsafe when the platelet count is less than 25,000 – 50,000. Fondaparinux is useful when thrombocytopenia due to heparin is suspected. There should be adjustment in the dose of concomitant antiplatelet therapy with thrombocytopenia. Dual antiplatelet therapy required for other indications can be continued when the platelet count is more than 50,000. It should be shifted to single antiplatelet therapy if the platelet count is between 25,000 to 50,000, and discontinued if the platelet count is less than 25,000.
Liver Disease- COVID-19 patients should be considered at high risk of VTE if they have advanced liver disease. Thromboprophylaxis with LMWH is a suggested standard of care for all patients with cirrhosis.
Kidney disease and COVID patients- are at high risk for bleeding and thrombotic complications and need to be monitored closely.
Authors acknowledge further researched to find out the precise mechanism behind the increased thrombogenicity of COVID-19 patients.
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