Article Figures & Data
Figures
- Figure 1
Standard TEG tracing. R time is reflective of enzyme/coagulation factor deficiency. α Angle is reflective of the thrombin burst. Maximal amplitude (MA) consists of 80% of platelet activity and 20% of fibrinogen. TEG, thrombelastography-platelet mapping.
- Figure 2
TEG platelet map tracing. Note the insert which shows the degree of platelet inhibition both as a percentage of total as well as the actual MA associated with the pathway. This assay shows 75.5% inhibition in the ADP pathway. ADP, adenosine diphosphate; MA, maximal amplitude; TEG, thrombelastography-platelet mapping.
- Figure 3
Algorithm for perioperative bridging of warfarin. INR, International Normalized Ratio; LMWH, low-molecular-weight heparin; UFH, unfractionated heparin.
Tables
- Table 1
Basic characteristics and interpretation of commonly used assays to assess platelet function
Test Medium Interpretation Comments Light transmission aggregometry Plasma Increased light transmission α increased platelet function Does not account for effect of blood cells on clotting Impedance aggregometry Whole blood Increased impedance α increased platelet function PFA-100 Whole blood Decreased closure time α increased platelet function Not approved for detection of clopidogrel VerifyNow Whole blood Akin to light transmission aggregometry TEG platelet map Whole blood Directly reports the percentage of inhibition in maximal platelet function Variable and high degree of inhibition noted due to illness and injury TEG, thrombelastography-platelet mapping.
- Table 2
CHAD2 scoring system for assessing thromboembolic risk
Condition Points C Congestive heart failure 1 H Hypertension: blood pressure consistently above 140/90 mm Hg (or treated hypertension on medication) 1 A Age ≥75 years 1 D Diabetes mellitus 1 S2 Prior Stroke or TIA or Thromboembolism 2 TIA, transient ischemic attack.
- Table 3
CHA2DS2-VASc scoring system for assessing thromboembolic risk
Condition Points C Congestive heart failure (or Left ventricular systolic dysfunction) 1 H Hypertension: blood pressure consistently above 140/90 mm Hg (or treated hypertension on medication) 1 A2 Age ≥75 years 2 D Diabetes Mellitus 1 S2 Prior Stroke or TIA or thromboembolism 2 V Vascular disease (eg, peripheral artery disease, myocardial infarction, aortic plaque) 1 A Age 65–74 years 1 Sc Sex category (ie, female sex) 1 TIA, transient ischemic attack.
- Table 4
Stroke risk by CHADS2 score
CHADS2 score Stroke risk % 95% CI 0 1.9 1.2 to 3.0 1 2.8 2.0 to 3.8 2 4.0 3.1 to 5.1 3 5.9 4.6 to 7.3 4 8.5 6.3 to 11.1 5 12.5 8.2 to 17.5 6 18.2 10.5 to 27.4 - Table 5
Stroke risk by CHA2DS2-VASc score
CHA2DS2-VASc score Stroke Risk % 95% CI 0 0 – 1 1.3 – 2 2.2 – 3 3.2 – 4 4.0 – 5 6.7 – 6 9.8 – 7 9.6 – 8 12.5 – 9 15.2 – - Table 6
HAS-BLED score to assess bleeding risk
HAS-BLED risk Score Hypertension 1 Abnormal Renal function 1 Liver function 1 Stroke 1 Bleeding 1 Labile INRs 1 Elderly: age >65 years 1 Drugs 1 Alcohol 1 Hypertension: systolic blood pressure >160 mm Hg; Abnormal renal function: presence of chronic dialysis or renal transplantation or serum creatinine ≥200 μmol/L; abnormal hepatic function: chronic hepatic disease or biochemical evidence of significant hepatic derangement (eg, bilirubin >2× upper limit of normal, in association with aspartate aminotransferase/alanine aminotransferase/alkaline phosphatase >3× upper limit of normal, etc); ‘Bleeding’ refers to previous bleeding history and/or predisposition to bleeding (eg, bleeding diathesis, anemia); ‘Labile INRs’ refer to unstable/high INRs or poor time in therapeutic range (eg, <60%); Drugs/alcohol use refers to concomitant use of drugs, such as antiplatelet agents, nonsteroidal anti-inflammatory drugs, alcohol abuse, etc.
INR, International Normalized Ratio.
- Table 7
Risk of bleeding by HAS-BLED score
Score Bleeding risk classification (% bleeds/100 patient-years) 0–1 Low risk (1.1%) 2 Intermediate risk (1.9%) >3 High risk (4.9%) - Table 8
Recommendations for timing of discontinuation of anticoagulation for elective surgery
Drug Timing of discontinuation Warfarin 5 days Direct thrombin inhibitors (dabigatran) CrCl ≥50 mL/min: 1–2 days
CrCl <50 mL/min: 3–5 daysCrCl (mL/min) Bleed risk: low Bleed risk: high (days) ≥50 24 hours 2-3 30–50 2 days 2-3 <30 2–4 days >5 Factor Xa inhibitors Rivaroxaban (Xarelto) ≥24 hours
ROCKET AF: ≥3 daysApixaban (Eliquis) Low-bleed risk: ≥24 hours
High-bleed risk: ≥48 hoursAntiplatelet agents Aspirin High-CV risk/minor: continue
Low CV/high-bleed risk: 7–10 daysClopidogrel 5 days Stents: bare metal stents—delay surgery for 6 weeks; drug eluding stents delay surgery for 6–12 months due to risk of occlusion; otherwise, consider continuing agents.
CV, cardiovascular.
