Warfarin Therapy for an Octogenarian Who Has Atrial Fibrillation

20 March 2001 | Volume 134 Issue 6 | Pages 465-474

In North America, atrial fibrillation is associated with at least 75 000 ischemic strokes each year. Most of these strokes occur in patients older than 75 years of age. The high incidence of stroke in very elderly persons reflects the increasing prevalence of atrial fibrillation that occurs with advanced age, the high incidence of stroke in elderly patients, and the failure of physicians to prescribe antithrombotic therapy in most of these patients. This failure is related to the increased risk for major hemorrhage with advanced age, obfuscating the decision to institute stroke prophylaxis with antithrombotic therapy.

This case-based review describes the risk and benefits of prescribing antithrombotic therapy for a hypothetical 80-year-old man who has atrial fibrillation and hypertension, and it offers practical advice on managing warfarin therapy. After concluding that the benefits of warfarin outweigh its risks in this patient, we describe how to initiate warfarin therapy cautiously and how to monitor and dose the drug. We then review five recent randomized, controlled trials that document the increased risk for stroke when an international normalized ratio (INR) of less than 2.0 is targeted among patients with atrial fibrillation. Next, we make the case that cardioversion is not needed for this asymptomatic patient with chronic atrial fibrillation. Instead, we choose to leave the patient in atrial fibrillation and to control his ventricular rate with atenolol. Later, when the INR increases to 4.9, we advocate withholding one dose of warfarin and repeating the INR test. Finally, when the patient develops dental pain, we review the analgesic agents that are safe to take with warfarin and explain why warfarin therapy does not have to be interrupted during a subsequent dental extraction.

Author and Article Information

From Washington University School of Medicine, St. Louis, Missouri; University of Washington and Veterans Affairs Puget Sound Health Care System, Seattle, Washington; and University of California, Davis, Sacramento, California.

Acknowledgments: The authors thank Gerald Banet, Paul Milligan, and William Katsiyiannis for their helpful suggestions on an earlier version of the manuscript.

Grant Support: By grant R01 HS10133 from the Agency for Healthcare Research and Quality.

Requests for Reprints: Brian F. Gage, MD, MSc, Division of General Medical Science, Washington University School of Medicine, Campus Box 8005, 660 South Euclid Avenue, St. Louis, MO 63110; e-mail, bgage{at}im.wustl.edu.

Current Author Addresses: Dr. Gage: Division of General Medical Science, Washington University School of Medicine, Campus Box 8005, 660 South Euclid Avenue, St. Louis, MO 63110.

Dr. Fihn: Division of General Internal Medicine, University of Washington and Veterans Affairs Puget Sound Health Care System¹⁵², 1660 South Columbian Way, Seattle, WA 98108.

Dr. White: Division of General Medicine, University of California, Davis, Suite 2400, PSSB, 4150 V Street, Sacramento, CA 95817.