Antithrombotic Therapy Flashcards
Clinical Vignette:
You’re evaluating a 65-year-old male patient with atrial fibrillation and mechanical heart valves who is undergoing a urologic procedure. He is currently on warfarin.
Question:
How many days before surgery should warfarin therapy be stopped to ensure an INR less than 1.5?
Options:
A) 2 days
B) 5 days
C) 7 days
D) 10 days
Correct Answer:
B) 5 days
Explanation:
Warfarin has a pharmacologic half-life of 36 to 42 hours. Most guidelines recommend stopping therapy 5 days before surgery to ensure an INR less than 1.5.
Memory Tool:
Remember “High 5 for INR < 1.5” to easily recall that 5 days cessation is recommended.
Reference Citation:
Paragraph 2, Douketis et al., 2012; Douketis, 2010.
Rationale:
The question assesses key knowledge in perioperative management, which has a direct bearing on both bleeding and thrombotic risks. It is based on guideline recommendations, providing a concrete basis for decision-making.
Clinical Vignette:
You have a 72-year-old patient with a history of VTE within the last 6 months. She is scheduled for a urologic surgery.
Question:
Based on Table 8.4, what is the risk stratum for this patient regarding anticoagulant therapy?
Options:
A) Low
B) Moderate
C) High
D) Not stratifiable
Correct Answer:
B) Moderate
Explanation:
Table 8.4 stratifies patients with a history of VTE within the last 3 months as high risk.
Memory Tool:
“6 is closer to 3 than 12”: Recall that 6 months is closer to 3 months than 12, positioning your patient in the high-risk category.
Reference Citation:
Table 8.4, Modified from Douketis JD, et al., Chest. 2012;141(2 Suppl):e326S–e350S.
Rationale:
Understanding risk stratification is essential for making informed decisions on perioperative antithrombotic therapy. It addresses the potential for both thrombosis and bleeding, fundamental considerations in urologic surgeries.
Question 1: Topic - Risk Stratification for Thrombosis
Clinical Vignette:
A 56-year-old male patient with a bileaflet aortic valve prosthesis is scheduled for a urological surgery. He has a history of atrial fibrillation but no prior stroke or transient ischemic attacks. His CHADS2 score is 1. What is his risk stratum for arterial or venous thrombosis?
Multiple Choice Options:
A. Low
B. Moderate
C. High
D. Not Applicable
Correct Answer:
B. Moderate
Explanation:
The patient has a bileaflet aortic valve prosthesis plus one or more risk factors (atrial fibrillation in this case), which places him in the “Moderate” risk stratum for arterial or venous thrombosis.
Memory Tool:
Think of “Moderate” as the middle ground where additional risk factors make the patient’s profile a bit more complex.
Reference Citation:
Table 8.4, Paragraph 1
Rationale:
This question emphasizes the importance of correctly stratifying patients for thrombotic risk, especially when they are scheduled for surgeries like urological procedures.
Question 2: Topic - Atrial Fibrillation and Thrombosis Risk
Clinical Vignette:
A 64-year-old female presents with atrial fibrillation. Her CHADS2 score is 4. What is her risk stratum for arterial or venous thrombosis?
Multiple Choice Options:
A. Low
B. Moderate
C. High
D. Not Applicable
Correct Answer:
C. High
Explanation:
The patient has a CHADS2 score of 4, which places her in the “High” risk stratum for arterial or venous thrombosis according to the table.
Memory Tool:
A CHADS2 score of 4 spells “High” trouble, so think of “4” as “Forewarning” for high risk.
Reference Citation:
Table 8.4, Paragraph 1
Rationale:
Understanding the risk stratification in atrial fibrillation is crucial as it guides anticoagulant therapy, which can have a significant impact on patient outcomes.
Question 3: Topic - VTE and Thrombosis Risk
Clinical Vignette:
A 72-year-old male had a single VTE event 14 months ago. He has no other risk factors. What is his risk stratum for arterial or venous thrombosis?
Multiple Choice Options:
A. Low
B. Moderate
C. High
D. Not Applicable
Correct Answer:
A. Low
Explanation:
The patient had a single VTE event that occurred more than 12 months ago and has no other risk factors. This places him in the “Low” risk stratum for arterial or venous thrombosis.
Memory Tool:
Remember, “Low and Long Ago” for single VTE events that happened more than a year ago.
Reference Citation:
Table 8.4, Paragraph 1
Rationale:
Correctly identifying the risk stratum can guide the need for anticoagulant therapy, which is especially relevant in an aging population with various comorbidities.
Question 4: Topic - Mechanical Heart Valve and Thrombosis Risk
Clinical Vignette:
A 45-year-old female has a bileaflet aortic valve prosthesis and no additional risk factors. What is her risk stratum for arterial or venous thrombosis?
Multiple Choice Options:
A. Low
B. Moderate
C. High
D. Not Applicable
Correct Answer:
A. Low
Explanation:
The patient has a bileaflet aortic valve prosthesis without any additional risk factors. According to the table, this places her in the “Low” risk stratum for arterial or venous thrombosis.
Memory Tool:
For bileaflet aortic valve prosthesis, think “Bileaflet, By itself, Basic risk,” which means “Low” risk if no other factors are present.
Reference Citation:
Table 8.4, Paragraph 1
Rationale:
Identifying the correct risk stratum for patients with mechanical heart valves is critical for appropriate clinical decision-making, especially in surgical settings.
Question 5: Topic - Atrial Fibrillation and Thrombosis Risk
Clinical Vignette:
A 60-year-old male with atrial fibrillation has a CHADS2 score of 2 and no history of stroke or transient ischemic attacks. What is his risk stratum for arterial or venous thrombosis?
Multiple Choice Options:
A. Low
B. Moderate
C. High
D. Not Applicable
Correct Answer:
A. Low
Correct Answer:
A. Low
Explanation:
The patient has a CHADS2 score of 0–2 and no prior stroke or transient ischemic attacks. This places him in the “Low” risk stratum for arterial or venous thrombosis according to the table.
Memory Tool:
CHADS2 score of 0–2 with no stroke history? Think “Too Low to Worry” as a quick mnemonic.
Reference Citation:
Table 8.4, Paragraph 1
Rationale:
This question is essential for understanding that a CHADS2 score alone is not sufficient to place a patient in a higher risk category if there is no history of stroke or transient ischemic attacks.
Question 6: Topic - VTE and Thrombosis Risk
Clinical Vignette:
A 50-year-old female had a VTE event 9 months ago. What is her risk stratum for arterial or venous thrombosis?
Multiple Choice Options:
A. Low
B. Moderate
C. High
D. Not Applicable
Correct Answer:
B. Moderate
Explanation:
The patient had a VTE within the past 3–12 months, which places her in the “Moderate” risk stratum for arterial or venous thrombosis according to the table.
Memory Tool:
Remember, “Moderate is the Middle,” and 3–12 months is the middle ground between a recent and a long-ago VTE event.
Reference Citation:
Table 8.4, Paragraph 1
Rationale:
Correct risk stratification for VTE is crucial for determining the need for anticoagulant therapy, especially in patients with recent events.
Question 7: Topic - VTE and Thrombosis Risk
Clinical Vignette:
A 70-year-old male has been diagnosed with nonsevere thrombophilic conditions like heterozygous factor V Leiden. What is his risk stratum for arterial or venous thrombosis?
Multiple Choice Options:
A. Low
B. Moderate
C. High
D. Not Applicable
Correct Answer:
C. High
Explanation:
The patient has nonsevere thrombophilic conditions like heterozygous factor V Leiden, which places him in the “High” risk stratum for arterial or venous thrombosis according to the table.
Memory Tool:
Think of “High Five for Factor V” to remember that factor V Leiden puts you in the “High” risk category.
Reference Citation:
Table 8.4, Paragraph 1
Rationale:
Understanding the impact of thrombophilic conditions on risk stratification is crucial for appropriate management and therapy selection.
Question 8: Topic - VTE and Thrombosis Risk
Clinical Vignette:
A 55-year-old female has been diagnosed with recurrent VTE. What is her risk stratum for arterial or venous thrombosis?
Multiple Choice Options:
A. Low
B. Moderate
C. High
D. Not Applicable
Correct Answer:
C. High
Explanation:
The patient has recurrent VTE, which places her in the “High” risk stratum for arterial or venous thrombosis according to the table.
Memory Tool:
Remember, “Recurrent VTE means Really High Risk.”
Reference Citation:
Table 8.4, Paragraph 1
Rationale:
Recurrent VTE significantly increases the risk of future thrombotic events, making it crucial to identify these high-risk patients for appropriate management.
Question 9: Topic - VTE and Thrombosis Risk
Clinical Vignette:
A 65-year-old male has been receiving palliative treatment for active cancer. What is his risk stratum for arterial or venous thrombosis?
Multiple Choice Options:
A. Low
B. Moderate
C. High
D. Not Applicable
Correct Answer:
C. High
Explanation:
The patient has active cancer that’s either been treated within the last 6 months or is palliative, placing him in the “High” risk stratum for arterial or venous thrombosis according to the table.
Memory Tool:
For active cancer, think “Cancer is a High Concern,” reminding you of the high-risk category.
Reference Citation:
Table 8.4, Paragraph 1
Rationale:
Patients with active cancer are at an elevated risk for thrombotic events, making correct risk stratification essential for appropriate clinical management.
Question 10: Topic - Mechanical Heart Valve and Thrombosis Risk
Clinical Vignette:
A 38-year-old male has a bileaflet aortic valve prosthesis along with atrial fibrillation and a history of stroke. What is his risk stratum for arterial or venous thrombosis?
Multiple Choice Options:
A. Low
B. Moderate
C. High
D. Not Applicable
Correct Answer:
C. High
Explanation:
The patient has a bileaflet aortic valve prosthesis and additional risk factors, such as atrial fibrillation and a history of stroke. According to the table, this places him in the “High” risk stratum for arterial or venous thrombosis.
Memory Tool:
Think “High Stakes for High Risks” when multiple risk factors like atrial fibrillation and stroke history are present alongside a bileaflet aortic valve prosthesis.
Reference Citation:
Table 8.4, Paragraph 1
Rationale:
Multiple risk factors in patients with mechanical heart valves necessitate a higher level of vigilance and may require more aggressive therapeutic strategies.
Question 11: Topic - Atrial Fibrillation and Thrombosis Risk
Clinical Vignette:
A 50-year-old female has atrial fibrillation and a CHADS2 score of 5. What is her risk stratum for arterial or venous thrombosis?
Multiple Choice Options:
A. Low
B. Moderate
C. High
D. Not Applicable
Correct Answer:
C. High
Explanation:
The patient has a CHADS2 score of 5, which places her in the “High” risk stratum for arterial or venous thrombosis according to the table.
Memory Tool:
Think “High 5 for High Risk” to remember that a CHADS2 score of 5 or higher puts you in the high-risk category.
Reference Citation:
Table 8.4, Paragraph 1
Rationale:
A high CHADS2 score indicates a significantly increased risk for thrombotic events, making it essential to understand how it impacts risk stratification and treatment choices.
CHADS2 Score
The CHADS2 score is a clinical prediction rule for estimating the risk of stroke in patients with non-rheumatic atrial fibrillation (AF), a common and serious heart arrhythmia associated with thromboembolic stroke. The acronym CHADS2 stands for:
C: Congestive heart failure (1 point)
H: Hypertension (1 point)
A: Age ≥75 years (1 point)
D: Diabetes Mellitus (1 point)
S2: Prior Stroke or TIA or thromboembolism (2 points)
The total score is calculated by summing up the points for each risk factor present in the patient, and it ranges from 0 to 6. A higher score indicates a higher risk of stroke.
Bridging Anticoagulation
“Bridging” anticoagulation refers to the practice of temporarily administering a short-acting anticoagulant, usually low-molecular-weight heparin (LMWH) or intravenous unfractionated heparin, during the perioperative period when long-acting oral anticoagulants are held.
How It’s Performed:
Preoperative Phase: The oral anticoagulant is stopped a few days before surgery to allow for its anticoagulant effect to wane.
Bridging Phase: Starting about 2 days after stopping the oral anticoagulant, a short-acting anticoagulant like LMWH is administered subcutaneously.
Surgery Day: The bridging anticoagulant is usually stopped 24 hours before the procedure.
Postoperative Phase: Bridging is resumed postoperatively, usually within 24 hours after surgery, once the risk of surgical bleeding is low.
Resumption: The long-term oral anticoagulant is restarted when it’s safe, and the bridging anticoagulant is discontinued once the oral agent reaches its therapeutic level.
