Atrial fibrillation (or, “A Fib”) is a common disorder of the heart. The incidence of A Fib increases with age. As the population ages, one projection estimates that almost 6 million people will have A Fib by 2050. One of the predominant risks of A Fib is stroke. The errant, inefficient beating of the heart associated with A Fib can lead to the build up of a blood clot (or, thrombus) within the heart. These clots can break loose (or, embolize) and travel into the arteries of the brain causing blockages. A “thromboembolic stroke” occurs when a blood clot cuts off blood flow, deprives the brain of oxygen and causes brain damage.
To reduce the risk of stroke from A Fib, physicians prescribe anticoagulants, such as Coumadin or Warfarin, to prevent clot formation. But anticoagulation, if used improperly, can cause a different kind of stroke — a brain bleed or “hemorrhagic stroke.”
Dosing and monitoring are critical to the safe and effective use of anticoagulation to prevent strokes in patients with A Fib. Dosing varies from patient to patient. The goal of anticoagulation is to achieve a “therapeutic INR.” INR refers to the test used to determine how effective anticoagulation is in preventing clot formation in a patient. A therapeutic INR falls within a range that prevents clot formation but also minimizes the risk of a bleeding complication. INR clinics have been set up to make it easy for patients to periodically obtain the blood work used by their physician to maintain a therapeutic level of anticoagulation.
By carefully monitoring a patient’s INR, the physician reduces the patient’s risk of both thromboembolic stroke and hemorrhagic stroke. However, when physicians fail to properly dose or monitor a patient on anticoagulation, the patient is put at an unnecessary risk of stroke. Everyone agrees that it is below accepted standards of medical care to put a patient at risk unnecessarily.
Dosing of anticoagulation varies from patient to patient. Further, the anticoagulation needs of a patient can change over time. For example, studies show that the amount of Warfarin needed to achieve a therapeutic level declines with age. A a result, the risk of warfarin-related bleeding increases for elderly patients. In Hylek EM, et al. An Analysis of the Lowest Effective Intensity of Prophylactic Anticoagulation for Patients With Nonrheumatic Atrial Fibrillation. N Engl J Med. 1996;335:540-546, the authors found that elderly patients had nearly 3 times the rate of major bleeds as younger patients.
Paradoxically, another study, McCrory DC, et al. Physician Attitudes About Anticoagulation for Nonvalvular Atrial Fibrillation in the Elderly. Arch Intern Med. 1995;155:277-281, found that elderly patients (> age 80) are more likely to be under-anticoagulated than younger patients with A Fib. Other challenges exist in safely anticoagulating elderly patients in A Fib. Elderly patients are more prone to fluctuations in their INR and can take longer to return to the therapeutic range once they become over-anticoagulated.
For these reasons, INR levels must be carefully monitored and nontherapeutic levels must be promptly addressed. Given the foregoing examples, elderly may also require more frequent INR monitoring than younger patients. American Geriatrics Society guidelines recommend monitoring INR daily until stable, followed by testing 2 or 3 times weekly for 1 to 2 weeks, weekly for 1 month, and monthly thereafter. However, all patients on anticoagulation, old and young, require monitoring on a regimented basis.
When a physician fails to adequately monitor, or unsafe INR results are ignored, a claim for medical malpractice may exist under Ohio law. If a physician gives either too much Warfarin and a hemorrhagic stroke occurs, or gives too little Warfarin and an embolic stroke occurs, essential elements of a claim for medical negligence are met. Monitoring has become the standard of care and a necessary measure to protect patients with A Fib who are vulnerable to stroke.