High CFF MA on TEG Indicates Hypercoagulability from Elevated Fibrinogen
A high Maximum Amplitude (MA) on Citrated Functional Fibrinogen (CFF) TEG indicates a hypercoagulable state driven by elevated fibrinogen levels and increased clot strength, which increases thrombotic risk and may warrant anticoagulation therapy. 1
Understanding CFF MA
Maximum Amplitude (MA) represents the maximum strength of the clot and primarily reflects fibrinogen contribution when measured on the CFF assay. 1 The CFF test uses a platelet inhibitor (GPIIb/IIIa antagonist) to isolate fibrinogen's contribution to clot strength, distinguishing it from platelet-mediated clot firmness. 2
- Normal MA values typically range from 50-70 mm, though specific reference ranges vary by device and clinical context. 3
- Increased MA indicates hypercoagulability, which correlates with enhanced thrombotic risk. 1
- CFF MA values are consistently higher than ROTEM FIBTEM MCF values for the same fibrinogen concentration—for example, at Clauss fibrinogen levels of 1.9-2.1 g/L, median CFF MA is 16.3 mm versus FIBTEM MCF of 12.0 mm. 4
Clinical Significance and Thrombotic Risk
High CFF MA reflects elevated fibrinogen levels and predicts increased risk for thrombotic events. 1, 5
- Elevated MA has been associated with higher risk for ischemic events in cardiovascular disease patients. 5
- In stroke patients, higher MA tertiles independently predict unfavorable one-year functional outcomes (OR = 1.192, p = 0.022). 5
- Pregnancy naturally increases MA values due to physiologic hypercoagulability, with progressive increases throughout gestation. 2
Management Approach
For severe hypercoagulability with high thrombotic risk, consider therapeutic anticoagulation with low molecular weight heparin (LMWH), particularly in pregnant patients where LMWH is preferred over unfractionated heparin. 1
- In pregnancy, 40 mg enoxaparin demonstrates greater anticoagulant effect than 7500 IU unfractionated heparin, with 73% of patients becoming hypocoagulable versus only 47% with UFH. 1
- The anticoagulant effect on TEG is defined as a difference >25% between plain and heparinase R time samples. 2
- Women with thrombophilia receiving prophylactic LMWH show significant increases in MCF (the ROTEM equivalent of MA) while clotting times remain unchanged. 2
Special Clinical Contexts
Pregnancy and Preeclampsia
- Mild preeclampsia patients are more hypercoagulable than healthy pregnant women, but as severity worsens, coagulability paradoxically decreases, particularly when platelet counts fall below 100,000/mm³. 2
- Women with VTE risk factors post-delivery maintain similar postpartum hypercoagulability patterns regardless of delivery mode. 2
- Higher fibrinogen targets (>2.0 g/L) may be needed in obstetric hemorrhage management. 3
Obesity
- Increasing BMI shows a trend toward greater hypercoagulability, though the hypercoagulable effect of term pregnancy appears greater in magnitude than obesity alone. 2
Critical Pitfalls to Avoid
Anemia can paradoxically show hypercoagulable TEG results (including elevated MA) due to decreased blood viscosity, potentially masking true coagulopathy or exaggerating hypercoagulability. 1, 3
- TEG shows high coefficients of variance (7.1-39.9% for TEG parameters), requiring interpretation in clinical context. 1
- Results are not interchangeable between TEG and ROTEM devices—CFF MA values differ significantly from FIBTEM MCF values even at identical fibrinogen concentrations. 1, 4
- TEG is performed at 37°C and cannot assess hypothermia effects on coagulation. 1
- Standard TEG is insensitive to antiplatelet agents and cannot reliably detect platelet dysfunction. 1, 3
Monitoring and Follow-up
- Repeat TEG 15-30 minutes after any anticoagulation intervention to assess response. 1
- Consider correlation with Clauss fibrinogen levels, though be aware that individual Clauss values correspond with different CFF MA values. 4
- Amplitude at 10 minutes (A10) can predict final MA, allowing faster clinical decision-making without waiting for complete test results. 6