INR Goal for Ischemic Cardiomyopathy

For patients with ischemic cardiomyopathy on warfarin, target an INR of 2.5 with a therapeutic range of 2.0 to 3.0. 1

Primary Recommendation

Warfarin with an INR target of 2.5 (range 2.0-3.0) may be considered for prevention of recurrent ischemic events in patients with ischemic stroke or TIA who have dilated cardiomyopathy (Class IIb recommendation, Level of Evidence C). 1
Antiplatelet therapy alone is an equally acceptable alternative to warfarin for secondary stroke prevention in cardiomyopathy patients, as the evidence does not definitively favor one strategy over the other. 1
The FDA-approved warfarin dosing for various cardiac conditions consistently recommends an INR range of 2.0 to 3.0 for most thromboembolic prevention indications, including cardiomyopathy-related thromboembolism. 2

If warfarin is selected as the anticoagulation strategy, maintaining optimal INR control is essential:

Aim for time in therapeutic range (TTR) greater than 65% to maximize protection against recurrent stroke while minimizing bleeding risk. 1, 3
INR values below 2.0 significantly increase the risk of thromboembolism and recurrent ischemic stroke. 1, 3
INR values above 3.0 are associated with increased major bleeding risk, with intracranial hemorrhage risk rising significantly when INR exceeds 3.5. 1, 3

Establish a rigorous monitoring schedule to maintain therapeutic anticoagulation:

Check INR at least weekly during warfarin initiation until stable therapeutic levels are achieved. 3, 4
Once INR is consistently within the therapeutic range (2.0-3.0), reduce monitoring frequency to at least monthly. 3, 4
More frequent monitoring is required during intercurrent illness, dietary changes, medication adjustments, or any signs of bleeding. 1

Do NOT routinely combine warfarin with antiplatelet agents in isolated cardiomyopathy:

Antiplatelet agents should not be routinely added to warfarin to avoid additional bleeding risk in patients with cardiomyopathy alone. 1, 5
The exception is if the patient has concurrent acute myocardial infarction with documented left ventricular thrombus, in which case aspirin up to 162 mg/day may be added (Class IIa recommendation). 1, 5
For patients with mechanical prosthetic valves who experience embolic events despite adequate anticoagulation, adding aspirin 75-100 mg/day is reasonable if bleeding risk is acceptable. 1, 3

Choose warfarin over antiplatelet therapy when:

The patient has documented left ventricular thrombus on echocardiography or other cardiac imaging. 1
There is a history of systemic embolization or recurrent stroke despite antiplatelet therapy. 1, 5
The patient has severely reduced left ventricular ejection fraction (<25%) with dilated cardiomyopathy. 1

Choose antiplatelet therapy over warfarin when:

The patient has high bleeding risk (history of major hemorrhage, falls, poor medication adherence). 1
INR monitoring is not reliably accessible or the patient cannot maintain TTR >65%. 1
The patient has isolated ischemic cardiomyopathy without documented thrombus or prior embolization. 1, 5

Subtherapeutic anticoagulation is a frequent cause of treatment failure:

A case report documented non-ST elevation myocardial infarction from aortic root thrombus in an LVAD patient with ischemic cardiomyopathy whose INR was subtherapeutic at 1.6 despite warfarin therapy. 6
Historical INR control (TTR) is only weakly predictive of future INR control, so past good control does not guarantee future therapeutic anticoagulation. 7
Even patients with TTR ≥80% historically have limited predictive ability for maintaining future TTR ≥80% (C-index only 0.61). 7

Do not assume patient knowledge correlates with INR control:

Studies show no significant correlation between patient warfarin knowledge scores and actual INR control measures (count in therapeutic range, TTR, or INR standard deviation). 8
Continuous patient education and close monitoring remain essential regardless of perceived patient understanding. 8