Oral Anticoagulants and Nonvalvular A-fib: A Balancing Act

Bleeding risk
Patients should be advised of the major risk for bleeding associated with all anticoagulant therapies.²⁷ Screening for bleeding includes assessment of Hypertension, Abnormal renal and/or liver function, previous Stroke, Bleeding history, Labile INR, being Elderly, and currently prescribed Drugs and/or excessive use of alcohol (known as HAS-BLED) (see Table 4).^1,28 Use of a bleeding risk assessment tool such as HAS-BLED may help identify the patient’s risk but cannot be the basis for treatment decisions.^1,29

Despite efforts to decrease bleeding risks, patients should understand that hemorrhagic complications can still occur. Patients taking anticoagulants should be familiar with early signs and symptoms of bleeding (eg, sudden, severe headache; melena; hematemesis; nosebleeds) and should notify their health care provider immediately if any of these symptoms occur.^12-14,23

If bleeding occurs, it is recommended that anticoagulant treatment be stopped. In addition, depending on the severity of the bleeding, the clinician may elect to administer activated prothrombin complex concentrates, recombinant factor VIIa, or concentrates of factors II, IX, or X to reverse the effects of newer oral anticoagulants.¹ Vitamin K, the antidote for warfarin, is not effective on direct thrombin inhibitors or factor Xa inhibitors. Currently, there is no established means of reversing the anticoagulant effects of the newer oral anticoagulants.^12-14

FOLLOW-UP
Since optimal utilization of cardiovascular medication occurs in only 50% of the patient population, appropriate follow-up must be implemented to ­improve overall outcomes of pharmacologic therapy.³⁰ Follow-up protocols depend on multiple factors, including type of anticoagulation therapy, patient response to therapy, and patient comorbidities.³¹ Monitoring warfarin use is time-consuming and resource-intensive; laboratory monitoring requirements for the newer oral anticoagulants have not been established.³²

Patients taking warfarin should be vigilant in follow-up with serial laboratory measurements and dosage adjustments.²³ Once therapy is initiated, INR is monitored every two to four days until two therapeutic INR levels are obtained.^31,33 Monitoring can then be changed to once weekly until two more therapeutic levels are obtained.³¹ The INR monitoring interval can then be increased to every two to four weeks, with two weeks being a more conservative strategy.³³ The practitioner may want to consider advancing to four-week monitoring intervals once four therapeutic INR levels have been obtained.³¹ It may be necessary to return to two-to-four day monitoring of INR if a nontherapeutic INR is obtained, the patient becomes ill, a medication is changed, or the patient makes a significant dietary change.³¹

When to refer
Primary care practitioners can manage anticoagulation therapy safely and efficiently, but cardiology referral may be warranted in certain situations. For example, patients with complex cardiac disease may benefit from cardiology referral.⁷ Considerations for referral to a cardiologist for further evaluation may include

• Abnormal exercise stress test results
• Abnormal echocardiogram results
• 12-lead ECG that reveals rapid, irregular wide pre-excited QRS complexes⁵

Patients who are drug intolerant or who remain symptomatic on pharmacologic rate control should also be referred to cardiology.⁷ In addition, patients who may require a pacemaker or defibrillator or who may be candidates for ablation should also be referred to an electrophysiology specialist.⁷

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