Target INR for Warfarin After Embolic Stroke
For patients on warfarin following an embolic stroke, the target INR is 2.5 with a therapeutic range of 2.0-3.0, regardless of whether the stroke was cardioembolic from atrial fibrillation, left ventricular thrombus, or other cardiac sources. 1, 2
Standard INR Target for Most Embolic Strokes
The target INR of 2.5 (range 2.0-3.0) applies to the vast majority of embolic stroke patients, including those with persistent or paroxysmal atrial fibrillation, which is the most common cause of cardioembolic stroke 1, 3
For patients with acute myocardial infarction and identified left ventricular mural thrombus causing embolic stroke, the same INR target of 2.0-3.0 is recommended for at least 3 months and up to 1 year 1
Patients with rheumatic mitral valve disease (with or without atrial fibrillation) who have had embolic stroke should maintain an INR target of 2.5 (range 2.0-3.0) 1
For embolic stroke patients with dilated cardiomyopathy, warfarin with an INR of 2.0-3.0 may be considered, though evidence is less robust than for atrial fibrillation 1, 2
Higher INR Targets for Specific Valve Conditions
Patients with mechanical prosthetic heart valves who have had embolic stroke require a higher target INR of 3.0 (range 2.5-3.5), which is the only common scenario requiring anticoagulation beyond the standard 2.0-3.0 range 1, 3
If a patient with a mechanical valve has recurrent embolic stroke despite adequate anticoagulation at INR 2.5-3.5, adding aspirin 75-100 mg daily while maintaining the INR target of 3.0 (range 2.5-3.5) is reasonable if bleeding risk is not prohibitive 1, 2
Bioprosthetic heart valves without other thromboembolic sources may be managed with the standard INR of 2.0-3.0 1
Critical Monitoring Parameters
Patients should maintain time in therapeutic range (TTR) >65% to ensure optimal stroke prevention, as subtherapeutic INR significantly increases recurrent stroke risk 2
INR should be checked at least weekly during warfarin initiation, then at least monthly once stable and consistently within therapeutic range 2, 4
Subtherapeutic INR <2.0 dramatically increases the risk of recurrent thromboembolism and ischemic stroke 2, 5
INR levels >3.0 are associated with exponentially increasing bleeding risk, with intracranial hemorrhage risk rising significantly when INR exceeds 3.5 2, 6, 7
Common Pitfalls to Avoid
Do not routinely add antiplatelet agents to warfarin in embolic stroke patients (except for mechanical valves with recurrent events or acute coronary disease), as this substantially increases bleeding risk without proven additional benefit 1
Avoid excessive dose reductions (>20%) when INR is mildly elevated (e.g., 3.0-3.5), as this can lead to subtherapeutic anticoagulation and increased stroke risk 4
Warfarin-related intracerebral hemorrhage mortality is dose-dependent, with 68% of hemorrhages occurring at INR ≤3.0, emphasizing the importance of meticulous INR control even within the therapeutic range 7
Elderly patients (>75 years) have higher bleeding risk at any given INR level and require more frequent monitoring, though the target range typically remains 2.0-3.0 5, 4
For patients with recurrent embolic events despite therapeutic INR 2.0-3.0 and rheumatic mitral valve disease, adding low-dose aspirin 81 mg daily may be considered 1