Related Experiment Video

Updated: Sep 1, 2025

In Vitro Thrombosis Test for Ventricular Assist Devices
09:15

In Vitro Thrombosis Test for Ventricular Assist Devices

Published on: March 21, 2025

765

Time in Therapeutic Range With Vitamin K Antagonists in Congenital Heart Disease: A Multicentre Study

Samir Basmaji1, Michelle Samuel1, Azadeh Shohoudi1

  • 1Montreal Heart Institute, Université de Montréal, Montréal, Québec, Canada.

The Canadian Journal of Cardiology
|August 14, 2022
PubMed

Insights

Patients with congenital heart disease (CHD) on warfarin (Vitamin K antagonists) spent less than 42% of their time in the therapeutic range. This suboptimal anticoagulation control was linked to increased risks of blood clots and bleeding events.

Area of Science:

  • Cardiology
  • Pharmacology
  • Hematology

Background:

  • Vitamin K antagonists (VKAs) are crucial for managing atrial arrhythmias and Fontan palliation in congenital heart disease (CHD) patients.
  • Limited data exists on the time spent within the therapeutic range (TTR) for VKAs in this specific patient population.
  • This study addresses the knowledge gap concerning VKA efficacy and safety in CHD.

Purpose of the Study:

  • To determine the TTR in patients with CHD on VKAs for atrial arrhythmias or Fontan palliation.
  • To investigate the association between TTR and the occurrence of thromboembolic and bleeding events.
  • To identify factors influencing time outside the therapeutic range in this cohort.

Main Methods:

  • A multicentre North American cohort study involving patients with CHD receiving VKAs.
  • Time in therapeutic range (TTR) calculated using the Rosendaal linear interpolation method.
  • Generalized estimating equations employed to analyze factors associated with time outside the therapeutic range.

Main Results:

  • The study included 567 patients with a mean age of 33 years, predominantly female (56%).
  • Mean TTR was 41.9%, significantly below the recommended levels.
  • Thromboembolic events correlated with time below range (31.3% vs 19.1%), and bleeding events with time above range (32.5% vs 19.5%).

Conclusions:

  • Patients with CHD on VKAs achieve suboptimal TTR, spending less than 42% of monitoring time within the desired international normalized ratio (INR) range.
  • This limited TTR is associated with increased risks of both thromboembolic complications and bleeding events.
  • Improved anticoagulation management strategies are warranted for CHD patients on VKAs.
Abstract

More Related Videos

Testing the Efficacy of Pharmacological Agents in a Pericardial Target Delivery Model in the Swine10:05

Testing the Efficacy of Pharmacological Agents in a Pericardial Target Delivery Model in the Swine

Published on: July 7, 2016

8.4K
Implantation of the Syncardia Total Artificial Heart16:11

Implantation of the Syncardia Total Artificial Heart

Published on: July 18, 2014

35.4K

Related Concept Videos

Anticoagulant Drugs: Vitamin K Antagonists and Direct Oral Anticoagulants01:18

Anticoagulant Drugs: Vitamin K Antagonists and Direct Oral Anticoagulants

Oral anticoagulants are vital tools in preventing and treating blood clotting disorders. This diverse class of medications can be categorized as vitamin K antagonists, exemplified by warfarin, and direct thrombin inhibitors (DTIs), such as dabigatran, as well as factor Xa inhibitors, including rivaroxaban.
Warfarin, a prominent vitamin K antagonist family member, exerts its effect by inhibiting the enzyme VKORC1 (vitamin K epoxide reductase complex 1). By hindering this enzyme, warfarin...
1.3K
Venous Thrombosis III: Interprofessional Care01:29

Venous Thrombosis III: Interprofessional Care

Venous thrombosis requires effective prevention and treatment strategies to improve patient outcomes and reduce potential complications.Prevention StrategiesHealthcare providers must prioritize preventing venous thromboembolism (VTE) for all adult patients upon admission. Interventions depend on bleeding and thrombosis risk, medical history, current medications, diagnoses, planned procedures, and patient preferences. Patients on bed rest should change positions every two hours and, if not...
18
Therapeutic Index01:13

Therapeutic Index

The therapeutic index of a drug is a key parameter in pharmacology that quantifies the relative safety of a drug by calculating the ratio between the dose that causes toxicity in half the population (50%) to the dose that proves to be effective for half the population (50%). It provides a spectrum of doses for a particular drug ranging from effective to potentially toxic. To illustrate, consider an anticoagulant agent like warfarin. It possesses a narrow window within its therapeutic index to...
4.7K
Drug Concentration Versus Time Correlation01:15

Drug Concentration Versus Time Correlation

The plasma drug concentration-time curve is a crucial tool in pharmacokinetics, representing the drug's concentration in plasma at different time intervals post-administration. This curve illustrates the drug's journey from absorption into the systemic circulation, distribution to body tissues, and eventual elimination through excretion or biotransformation.
Two pivotal parameters are the minimum effective concentration (MEC) and the minimum toxic concentration (MTC). The MEC is the...
1.1K
Anticoagulant Drugs: Low-Molecular-Weight Heparins01:30

Anticoagulant Drugs: Low-Molecular-Weight Heparins

Hemostasis is a crucial process that prevents excessive blood loss from damaged blood vessels. It involves various mechanisms such as vasoconstriction, platelet adhesion and activation, and fibrin formation. The importance of each mechanism depends on the type of vessel injury. In contrast, thrombosis is the abnormal formation of a blood clot within the blood vessels, leading to potential complications if the clot obstructs blood flow. Thrombosis can be caused by increased coagulability of the...
867
Determination of Michaelis Constant and Maximum Elimination Rate01:20

Determination of Michaelis Constant and Maximum Elimination Rate

The Michaelis constant (KM) and the theoretical maximum process rate (Vmax) are vital parameters in the Michaelis-Menten equation, central to many biochemical reactions. They provide essential insights into enzyme kinetics and drug metabolism.
These parameters can be estimated by analyzing plasma concentration data post-drug administration. A notable example of this application is phenytoin, a drug with capacity-limited kinetics. It's recommended that phenytoin should be administered at two...
166