Dr.S.Venkatesan MD

Oral anticoagulant usage has been steadily increasing for variety of  indications.Dengue fever is also  appearing in different avatars with  low platelet counts  and bleeding being a primary risk.

I was recently contacted by a physician , regarding a therapeutic dilemma .A young lady with mitral prosthetic valve and a febrile illness diagnosed as dengue . She has a platelet  count of 100,000 .She is on regular warfarin and aspirin .The physician  wanted to know , should he stop the OAC and aspirin ?

What are the options ?

• Confirm if it is really dengue.
• Look for clinical bleeding.INR, platelet function tests are not helpful.
• Continue OAC.You can do that in most situations.
• Stop OAC only if there is clinical bleeding  episode.
• Anti-platelet drug usage  is more tricky .One may stop it if the trend of falling platelet is steep by at least two serial measurement.(or 50% fall from baseline)
• Fresh blood and platelet infusions should be ready .
• Finally and most importantly , Inform the patient and family about the difficult decision we are making.

*Is  OAC  safer than aspirin and clopidogrel in dengue ?

It is believed OAC has no major  Impact on platelet function .It may not  pose a threat of excess bleeding in the setting of  falling platelet levels .(*Evidence base -nil )

Another potential situation : DES and dengue

The number of DES in developing countries are increasing  where Dengue is endemic . It is not a surprising  to expect  both to  occur together.

Anti-platelet agents  can be problematic .It is better to withhold it during the active phase of dengue.(If the  stent has recently  been deployed you have no option !)

Final message

1.  Prosthetic valve , Warfarin Dengue .

2. DES, Dual antiplatelet agents ,Dengue.

They  extraordinary events  throw a complex therapeutic task .There are only two options .Continue or discontinue ! Whichever way you do , you explain to your clients (patients!)  the (un)reality games we play.

My personal option would be , with hold all hematological drugs during the active phase of dengue .

It is better to believe in the  natural thrombus fighting force . Leave the job of anti-platelet action  to the dengue virus for a week or two and give oral anticoagulants and dual anti-platelet agents a holiday

It may be foolish to rely on the dengue virus to guard against  prosthetic  valve  and DES thrombus , In reality we have to do that !

Reference

No reference exists.It is a statistical mind game.Individual assessment  should prevail. Either way, if something adverse happens court of law should protect us !