Finding atrial fibrillation in the hospital

Challenges include differentiating transient and persistent cases.

Despite being one of the most common inpatient diagnoses and a major risk factor for stroke, atrial fibrillation (AF) often remains undiagnosed until a patient is hospitalized for another condition. Once AF has been identified, there's the challenge of determining if it's a transient event related to the cause of hospitalization or a persistent problem requiring ongoing treatment.

Recent research has highlighted how commonly this issue appears in hospital practice. A study published in the May 2019 CHEST found that 18% of patients hospitalized for end-stage chronic obstructive pulmonary disease (COPD) had AF and that these patients were more likely to require invasive mechanical ventilation.

Image by Getty Images
Image by Getty Images

Anticoagulation is the best treatment to lower stroke risk in patients with AF, but it must be carefully managed and tailored to meet individual needs, experts say. Hospitalists have to balance concerns such as the elevated risk of bleeding in frail elderly patients while facing uncertainties that include the likelihood of AF recurrence.

“Knowing whether or not to continue anticoagulants after patients return to sinus rhythm is a tricky decision,” said Daniel Singer, MD, professor of medicine at Harvard Medical School in Boston, whose research focuses on stroke prevention in AF. “You can never be 100% sure that AF is transient even if patients are not in AF after stopping anticoagulation. Studies have shown that over time a significant percentage of these patients will develop AF with no obvious precipitant.”

Initiating treatment

The first goal in AF treatment is achieving rate and rhythm control, said Andreas Barth, MD, an electrophysiologist and cardiologist at Johns Hopkins Hospital in Baltimore. For patients with no symptoms, beta-blockers or calcium-channel blockers can usually bring down their heart rate to normal levels. Patients with noticeable symptoms, such as palpitations, should undergo electrical or pharmacological cardioversion.

“The higher the heart rate, the more likely there will be symptoms and patients will report being uncomfortable,” said Dr. Barth. “When a patient has a consistently high heart rate and multiple symptoms, we recommend cardioversion to get them out of AF into regular rhythm.”

Initial treatment should be based on the patient's risk for stroke, said Andrew Beaser, MD, an electrophysiologist and assistant professor of medicine at the University of Chicago. To determine that, physicians use the CHA2DS2-VASc scoring system, which looks at such factors as age, sex, and comorbidities, to make decisions about anticoagulation.

According to expert guidelines published in CHEST, anticoagulation should not be offered to low-risk patients (score of 0 in males, 1 in females), who are generally younger than age 65 years and have no underlying heart disease. Anticoagulation is recommended for patients with at least one non-sex risk factor.

If patients are eligible for anticoagulation, it should be started as early as possible, said Dr. Beaser. “Patients need to be fully anticoagulated at the time of cardioversion, whether electrical or chemical, so initiating therapy at discovery is very helpful.”

How long to continue anticoagulation can be a difficult decision, but recent research suggests that AF, even when precipitated by underlying conditions and assumed to be transient, can recur long after discharge. A meta-analysis of 35 studies, published in the June 2019 Stroke, included more than 2.4 million patients and found that those with new-onset perioperative AF had significantly higher risk of stroke and mortality within 30 days and over the long term.

The results contradict a common belief that postoperative AF is usually transient and converts to sinus rhythm before discharge, the authors noted.

“Not long ago, AF precipitated by something else was regarded as a transient phenomenon that was unlikely to come back once the underlying issues were resolved,” said Steven Lubitz, MD, MPH, a cardiac electrophysiologist at Massachusetts General Hospital in Boston and associate professor of medicine at Harvard Medical School. “More recently, we're seeing that even though the short-term risk may be lower than if AF was discovered alone, the long-term recurrence rate is substantial.”

Screening for AF

Considering the high risk of stroke in AF patients, there is increasing interest in electrocardiography screening. While screening is primarily an outpatient issue, some researchers have looked into the effectiveness of identifying AF and initiating anticoagulation in the hospital.

For example, one study of 327 hospitalized elderly patients, published in the April 2018 BMJ, found that daily short-term rhythm strip recordings identified an additional 13% of patients with AF who could potentially benefit from anticoagulation.

The study had limitations: 70 of the patients were unable to hold the device and may not have been suitable for anticoagulation due to the severity of their underlying conditions. In addition, of the 28 new patients with AF, eight had contraindications to anticoagulation. However, the results point to a growing recognition that screening in the hospital may be feasible and that stroke can be the first manifestation of AF.

Whether discovered incidentally or through screening, diagnosis of previously unrecognized AF in the hospital can improve transitions of care to the outpatient team, said Dr. Lubitz.

“We can then think about the short- to intermediate-term plan, including anticoagulation, and plan the transition in a thoughtful way,” he said. “We can hand off a plan that includes investigating for recurrent AF and managing stroke prophylaxis with or without anticoagulants.”

Although routine screening in the outpatient setting could improve detection of AF, the most recent U.S. Preventive Services Task Force (USPSTF) guidelines cite insufficient evidence to recommend it. The guideline notes that electrocardiography carries the risk of misdiagnosis and unnecessary testing and treatments, including anticoagulation and bleeding risks.

That thinking could change as technological advances make outpatient screening easier, said Dr. Singer.

At-home monitoring has traditionally involved Holter monitors with electrodes attached that patients wear for as long as 30 days and that send reports to their physician. However, these can be cumbersome and uncomfortable for older patients, he observed. New portable devices, such as the Apple Watch, have the potential to make screening more convenient and widespread.

Such devices are capable of assessing and tracking heart rhythm and potentially integrating that information with clinical care. However, the technology is evolving and there are not yet enough data to know whether these devices will help prevent strokes or lead to overdetection and unnecessary treatment.

“There are still a lot of unanswered questions regarding screening,” said Dr. Lubitz. “We still don't know whether or not screening prevents strokes or how much burden of AF is important. With continuous monitoring in the outpatient setting, detection is likely to increase but we don't know how much AF is worrisome and what can be safely monitored and not treated.”

More outpatient screening and better integration of patient records could potentially improve hospital care in the future by providing hospitalists with data on AF history at admission, experts noted.

Assessing bleeding risks

In the decision whether to treat AF with anticoagulants, stroke risk is the primary consideration, but physicians must also balance the risk of bleeding. The HAS-BLED scoring tool, which looks at age, alcohol use, liver and renal disease, hypertension, and other factors, is regarded as the simplest and most accurate way of risk stratifying patients.

Some factors can be modified to lower risk, such as uncontrolled blood pressure or use of aspirin or NSAIDs. Others—such as risk of falls—are more difficult to quantify, requiring clinical judgment and consultations with patients where possible.

“AF patients are mostly older and often at higher risk of bleeding,” noted Dr. Singer. “Falling and hitting their head can cause intracranial bleeds, which can be fatal if they are taking anticoagulants.”

Fear of falls underlies most decisions not to put frail, elderly patients on anticoagulants, despite guideline recommendations. In general, however, there needs to be a very strong reason not to use anticoagulants, said Dr. Beaser.

“We usually err on the side of giving a blood thinner because the strokes people get from AF are so devastating—not always fatal but very debilitating,” he said. “Patients would have to have multiple serious risks for bleeding to outweigh the risk of stroke, such as being unable to stand on their own or a history of frequent falls, injuries, and passing out.”

Alternatives to anticoagulation are emerging with developing technology, noted Dr. Barth. One is a closure device that is inserted into the left atrial appendage, where the majority of clots arise.

Another potential alternative is the lariat procedure, which surgically closes off the left atrial appendage, Dr. Barth said. This procedure is typically performed concomitantly in patients undergoing surgery for other reasons, such as valve replacement or bypass.

Still, some patients are so fearful of bleeding that they refuse treatment. Dr. Beaser cited one case of a man with newly diagnosed AF who declined anticoagulation because his father had bled to death while taking warfarin.

“He was so adamantly against it that there was nothing I could say to change his mind,” he said. “It then became my goal to make sure he understood the risks. It's an example of why physicians sometimes have to go against the evidence base.”