Special considerations in application of the 4Ts score to cardiac surgery patients
| Component of 4Ts score . | Cardiac surgery population considerations . |
|---|---|
| Timing of platelet count fall | A biphasic platelet count pattern is typical of HIT after CPB surgery Early-onset and persistent thrombocytopenia after CPB is rarely HIT |
| Thrombocytopenia | Percent fall in platelet count is calculated from the highest platelet count that immediately precedes the putative HIT-related platelet count decline, to the nadir value The nadir platelet count need not fall below 150 × 109/L, particularly in surgical patients who have postoperative thrombocytosis |
| Thrombosis or other sequelae | Digital ischemia due to hypotension, vasopressors, non-HIT DIC, and/or underlying peripheral arterial disease may mimic HIT-associated small-vessel thromboembolism |
| Other causes of thrombocytopenia | Common alternative causes in cardiac patients include CPB, IABP, ECMO, LVAD, infection, and other medications that can cause thrombocytopenia (eg, glycoprotein IIb/IIIa antagonists) |
| Component of 4Ts score . | Cardiac surgery population considerations . |
|---|---|
| Timing of platelet count fall | A biphasic platelet count pattern is typical of HIT after CPB surgery Early-onset and persistent thrombocytopenia after CPB is rarely HIT |
| Thrombocytopenia | Percent fall in platelet count is calculated from the highest platelet count that immediately precedes the putative HIT-related platelet count decline, to the nadir value The nadir platelet count need not fall below 150 × 109/L, particularly in surgical patients who have postoperative thrombocytosis |
| Thrombosis or other sequelae | Digital ischemia due to hypotension, vasopressors, non-HIT DIC, and/or underlying peripheral arterial disease may mimic HIT-associated small-vessel thromboembolism |
| Other causes of thrombocytopenia | Common alternative causes in cardiac patients include CPB, IABP, ECMO, LVAD, infection, and other medications that can cause thrombocytopenia (eg, glycoprotein IIb/IIIa antagonists) |
Adapted from Pishko and Cuker4 with permission from Georg Thieme Verlag KG.
CPB, cardiopulmonary bypass; IABP, intra-aortic balloon pump; DIC, disseminated intravascular coagulation; ECMO, extracorporeal membrane oxygenation; LVAD, left ventricular assist device.