HOW I DO – DVT – Other Important Points – PART – 16

HOW I DO – DVT – Other Important Points – PART – 16

(All the articles published in past are available at www.shyamhemoncclinic.com/blog/)

Question: In last part, we covered some important points related to VTE PREVENTION 1. Over four hours of air travel should be considered for DVT prophylaxis, especially if other risk factors exist e.g. cancer, obesity, past history of VTE, genetic factor. Stay mobile and hydrated. Avoid alcohol. Use of medicines is highly variable. 2. We reviewed list of patients considered high risk for DVT during hospitalization. 3. Indian data is small and variable. With change in lifestyle, our incidence of western diseases is increasing. Hence DVT prophylaxis should be more seriously considered. 4. VTE is the Number 1 Preventable Cause of Death in hospitalized patients. 5. Most common drug used is LMWH e.g. enoxaparin 0.4 mg subcutaneous once a day. In some cases, fondaparinux, unfractionated heparin, or even oral agents can be used for prophylaxis. Mechanical compression devices are used only when medicines are contraindicated.

Are there any other important points related to DVT/PE that we need to highlight?

Answer: Yes this is a very wide topic. But let us briefly review few important points:

1. Duration of Anticoagulation for those with a DVT only, and a transient risk factor e.g. post surgery, or immobilization, is 3 months. Longer anticoagulation is not required. Also, these patients should NOT be tested for hereditary risk factors.
2. Those with DVT without any obvious transient risk factor need a longer duration of anticoagulation i.e. at least six months, preferably longer if there is low risk for bleeding. How long is not defined, but it is advised as long term, indefinite if bleeding risk is lower. Basically balancing risk of recurrent DVT versus bleeding. If risk of bleeding is high, stop at 3 months or longer. But if risk is medium, you can use lower dose NOAC/DOAC to extend anticoagulation. This lower dose is preferred over only aspirin. However, if NOAC is not feasible for some reasons, aspirin can be used for longer duration anticoagulation.

No test is used to guide duration of anticoagulation e.g. D dimer, repeated venous doppler to look for residual thrombosis or any risk scores. Basically if DVT is unprovoked, the risk for recurrent DVT outweighs risk of bleeding in general. Unless there are obvious risk factors for bleeding.

3. For those with pulmonary embolism, same principle apply as for unprovoked DVT, with regard to duration of anticoagulation.
4. Goal INR for patients on warfarin for almost all indications is between 2 and 3. Higher or lower are not advised.
5. There are specific guidelines re reversal of warfarin based on presence of any bleeding, and level of PT/INR. For asymptomatic no bleeding, only high INR, FFP or PCC are avoided. For those with critical bleed or need for urgent surgery, PCC (prothrombin complex concentrate) are preferred. For others, low dose vitamin k or just holding warfarin are advised, depending on level of PT/INR. If PCC is not available, FFP is next choice. Novoseven (rFactorVIIa) can also be used, though not preferred.
6. Reversal of DOAC depends on which specific DOAC is in use. There are different products for different DOAC. PCC can be used if specific antidote is not available. FFP alone is too weak to have significant effect, but can be used if no other option, considering cost of PCC.

Activated charcoal can be used if taken within two hours. Dialysis can be used to clear Dabigatran.

If more than 24 hours have passed since last dose of DOAC, and renal function is normal, reversal is not required.

7. Guidelines recommend against use of compression stocking as a routine measure to prevent post thrombotic syndrome.
8. Some patients are found to have incidental subsegmental pulmonary embolism during CT scan of chest done for other reasons. What to do with these patients, who have no DVT, but only subsegmental PE? CHEST guidelines recommend observation alone for these patients if they are otherwise low risk for VTE. But if they are at otherwise high risk for VTE e.g. cancer patients, then they should receive standard anticoagulation.
9. For obese patients, standard DOAC dosing can be used up to 120 kg weight.
10. For many DVT patients, otherwise stable, oral DOAC can be started as first line of therapy without any injectable treatment. Many of these can be treated as outpatient, if there is good follow up and monitoring possible. Outpatient treatment should be tried in very highly selected patients in India, considering our support services and patient reliability.
11. Know which DOAC you are using, preferably use same for all patients. This way you and your team will be very conversant with dosing. For example, only dabigatran has a fixed dose from day one. Rivaroxaban and Apixaban have a loading dose for 21 and 7 days respectively. I see a number of patients where loading dose is continued or starting dose is lower. Rivaroxaban is preferably given after food. Other issue we see is patients with worsening renal function continuing same dose DOAC. Or no monitoring of creatinine for several months to years. Patients and physicians frequently take these medicines lightly. We recently had a patient with high creatinine, on rivaroxaban for a prolonged period, came in with bleeding. Such patients need extra monitoring, and even tests like antiXa to be sure. October 14^th 2025 Dr Chirag A. Shah; M.D. Oncology/Hematology (USA), 9998084001. Diplomate American Board of Oncology and Hematology. Ahmedabad. drchiragashah@gmail.com www.shyamhemoncclinic.com