What are the causes of elevated Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT) in patients with Heart Failure?

From the Guidelines

Elevated Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT) in patients with Heart Failure are most likely caused by antithrombotic agents such as oral anticoagulants, which are commonly used to reduce the risk of stroke in these patients, particularly those with atrial fibrillation 1.

Common Causes

• Antithrombotic therapy: Patients with heart failure are often treated with antithrombotic agents, which can increase the risk of bleeding and elevate PT and APTT levels 1.
• Oral anticoagulants: The use of oral anticoagulants, such as warfarin, can increase PT levels and is a common cause of elevated PT in patients with heart failure 1.

Clinical Context

In the context of heart failure, the use of antithrombotic therapy is crucial to reduce the risk of thromboembolic events, particularly in patients with atrial fibrillation 1. However, this therapy can also increase the risk of bleeding, highlighting the need for careful monitoring of PT and APTT levels in these patients.

Key Considerations

• Atrial fibrillation: Patients with heart failure and atrial fibrillation are at increased risk of stroke and may require oral anticoagulants, which can elevate PT levels 1.
• Previous vascular events: Patients with heart failure who have had previous vascular events may be treated with antithrombotic therapy, which can increase the risk of bleeding and elevate PT and APTT levels 1.

From the Research

Causes of Elevated Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT)

• The causes of elevated PT and APTT can be due to various factors, including:
  • Acquired conditions, such as vitamin K deficiency, liver disease, and anticoagulant therapy 2
  • Congenital conditions, such as factor deficiencies and lupus anticoagulant 2, 3
  • Laboratory artifacts, such as preanalytical interferences 3
• In patients with heart failure, elevated PT and APTT can be caused by:
  • Anticoagulation therapy, which can lead to increased PT and APTT levels 4, 5
  • Liver disease, which can cause prolonged PT and APTT due to decreased production of coagulation factors 2
  • Vitamin K deficiency, which can lead to increased PT levels 2
• The use of APTT mixing studies can help differentiate between factor deficiencies and inhibitors, and can improve the diagnostic accuracy of APTT results 6
• However, APTT results can be discordant with anti-factor Xa levels, particularly in patients with device obstruction and/or hemolysis, and can lead to overestimation of heparin concentration and under-anticoagulation 5

Specific Causes of Elevated PT and APTT

• Isolated prolonged PT can be caused by:
  • Vitamin K deficiency 2
  • Liver disease 2
• Isolated prolonged APTT can be caused by:
  • Lupus anticoagulant 2, 3
  • Factor deficiencies, such as factor VIII or factor IX deficiency 3
  • Anticoagulant therapy, such as heparin therapy 3, 5
• Prolonged PT and APTT can be caused by:
  • Liver disease 2
  • Anticoagulant therapy, such as warfarin or heparin therapy 2, 4, 5