Chest Guidelines 2012 - Hit

Front 1

Pathophys of HIT?

Back 1

heparin leads to formation of anti-PF4 IgG antibodies that recognize heparin on the surface of platelets which promotes binding, release of procoagulant factors, and thrombus formations in arterial and venous systems

Front 2

Risk of hit with LMWH vs UFH?

Back 2

UFH has 10x higher risk of HIT than LMWH

Front 3

Define thrombocytopenia

Back 3

platelet count of <150x10^9/L OR 30-50% fall even if nadir >150

Front 4

Typical onset of HIT?

Back 4

5-10 days after initiation of heparin; can occur within 24h if patient has previous exposure to heparin within last month to 100 days prior; ALSO thrombocytopenia can occur up to three weeks after exposure to heparin

Front 5

What clinical evaluation tool can be used for determining HIT?

Back 5

4Ts score

Front 6

Why is the HIT ELISA test only sensitive and not specific?

Back 6

Seroconversion to produce HIT antibodies does not always cause HIT as the antibodies have to be specific to both heparin and pf4 but some are pf4/polyvinyl sulfonate and thus not HIT producing; assays such as serotonin release assay (SRA) and heparin induced platelet activation are both specific and sensitive to HIT

Front 7

For patients receiving heparin in whom
clinicians consider the risk of HIT to be > 1%
we suggest that platelet count monitoring
be performed?

Back 7

every 2 or 3 days from day
4 to day 14 (or until heparin is stopped, whichever
occurs fi rst)

Front 8

For patients receiving heparin in whom
clinicians consider the risk of HIT to be <1% we suggest that platelet counts?

Back 8

not be
monitored

Front 9

For patients exposed to heparin
within the past 100 days, we suggest what prior to starting heparin or
LMWH therapy?

Back 9

that a baseline
platelet count be obtained and that a repeat platelet count
should be drawn 24 h later, if feasible.

Front 10

S/sx of acute HIT?

Back 10

acute infl ammatory reaction (eg, fever,
chills) and/or cardiorespiratory symptoms (eg, hypertension,
tachycardia, dyspnea, chest pain, cardiorespiratory
arrest) within 30 min of drug administration.

Front 11

First step in tx of HITT (heparin induced thrombocytopenia complicate by thrombosis)?

Back 11

d/c all LMWH and UFH

Front 12

In patients with HITT, we recommend the
use of?

Back 12

nonheparin anticoagulants, in particular
lepirudin, argatroban, and danaparoid, over the
further use of heparin or LMWH or initiation/
continuation of VKA

Front 13

All possible HITT tx (but not all recommended by chest)?

Back 13

DTIs: lepirudin, desirudin, argatroban, bivalirudin
Xa inhibitors: danaparoid or fondaparinux

Front 14

brand name for desirudin?

Back 14

Iprivask

Front 15

brand name for lepirudin?

Back 15

Refludan

Front 16

brand name for argatroban?

Back 16

n/a

Front 17

brand name for bivalirudin?

Back 17

angiomax

Front 18

brand name for fondaparinux?

Back 18

Arixtra

Front 19

In patients with HITT who have normal
renal function, we suggest what tx?

Back 19

the use of argatroban
or lepirudin or danaparoid over other nonheparin
anticoagulants

Front 20

In patients with HITT and renal insuffi -
ciency, we suggest of what tx?

Back 20

the use of argatroban over
other nonheparin anticoagulants (argatroban is not renally cleared while lepirudin is)

Front 21

Should patients with HIT be transfused with platelets?

Back 21

No. Pts with HIT rarely have spontaneous bleeding despite low PLts. Also adding plts tends to increase the chances of developing thrombus (no direct evidence but safety is unlikely and unknown at this time)

Front 22

In patients with HIT and severe thrombocytopenia,
we suggest giving platelet transfusions when?

Back 22

only if bleeding or during the performance of an
invasive procedure with a high risk of bleeding
(Grade 2C) .

Front 23

Why is warfarin not started immediately after HIT?

Back 23

can produce a prothrombotic state as the anticoagulant protein C levels drop faster due to warfarin than prothrombin levels; need DTI or Xa inhibitor on board to start VKA after HITT

Front 24

In patients with strongly suspected or confi
rmed HIT, we recommend against starting VKA
until?

Back 24

platelets have substantially recovered (ie,
usually to at least 150K) over starting VKA
at a lower platelet count and that the VKA be
initially given in low doses (maximum, 5 mg of
warfarin or 6 mg phenprocoumon) over using
higher doses (Grade 1C) .

Front 25

We further suggest that if a VKA has
already been started when a patient is diagnosed
with HIT, then do what?

Back 25

, vitamin K should be administered

Front 26

In patients with confi rmed HIT, we recommend
that that the VKA be overlapped with
a nonheparin anticoagulant for?

Back 26

a minimum of
5 days and until the INR is within the target
range over shorter periods of overlap and that
the INR be rechecked after the anticoagulant
effect of the nonheparin anticoagulant has
resolved

Front 27

For patients with HITT, we suggest
VKA therapy or an alternative anticoagulant be continued for?

Back 27

3 months. For patients with HIT, we suggest
VKA therapy or an alternative anticoagulant be
continued for 4 weeks

Front 28

In patients with isolated HIT (HIT without
thrombosis), we recommend

Back 28

the use of lepirudin
or argatroban or danaparoid over the further
use of heparin or LMWH or initiation/continuation
of a VKA

Front 29

In patients with acute HIT (thrombocytopenic,
HIT antibody positive) or subacute HIT
(platelets recovered, but still HIT antibody positive)
who require urgent cardiac surgery, we suggest

Back 29

the use of bivalirudin over other nonheparin
anticoagulants and over heparin plus
antiplatelet agents

Front 30

In patients with acute HIT who require
nonurgent cardiac surgery, we recommend

Back 30

delaying
the surgery (if possible) until HIT has resolved
and HIT antibodies are negative

Front 31

In patients with acute HIT or subacute
HIT who require PCI, we suggest the use of

Back 31

bivalirudin (Grade 2B) or argatroban (Grade 2C)
over other nonheparin anticoagulants

Front 32

Why is argatroban preferred for dialysis pts with HIT?

Back 32

it is not renally cleared and dialytic clearance by high flux membranes is considered clinically insignificant

Front 33

In patients with a past history of HIT who
require ongoing renal replacement therapy
or catheter locking, we suggest?

Back 33

the use of
regional citrate over the use of heparin or
LMWH

Front 34

In pregnant patients with acute or subacute
HIT, we suggest

Back 34

danaparoid over other nonheparin
anticoagulants (Grade 2C) . We suggest
the use of lepirudin or fondaparinux only if
danaparoid is not available

Front 35

In patients with a history of HIT in
whom heparin antibodies have been shown to
be absent who require cardiac surgery, we suggest

Back 35

the use of heparin (short-term use only - less than 4 days)
over nonheparin anticoagulants

Front 36

In patients with a past history of HIT who
have acute thrombosis (not related to HIT) and
normal renal function, we suggest

Back 36

the use of
fondaparinux at full therapeutic doses until
transition to VKA can be achieved