Clinical Briefs

By Louis Kuritzky, MD, Clinical Assistant Professor, University of Florida, Gainesville. Dr. Kuritzky is an advisor for Endo, Kowa, Pricara, and Takeda.

Subclinical Atrial Fibrillation

Source: Healey JS, et al. Subclinical atrial fibrillation and the risk of stroke. N Engl J Med 2012;366:120-129.

I have been a student of atrial fibrillation (AF) for some time, but had never come upon the term "subclinical" AF until this New England Journal of Medicine publication. The authors point out that although AF is often brought to our attention by awareness of an arrhythmia, it is often asymptomatic — what they call subclinical. Indeed, it is not uncommon to see patients presenting with ischemic stroke, heart failure, or syncope, only to discover that asymptomatic AF is the underlying etiology.

Healey et al report on a population of hypertensive seniors in whom either a pacemaker or defibrillator had been implanted but who had no prior history of AF (n = 2580). The implanted devices were programmed to report any episode of heart rate 190 beats per minute (bpm) or greater. Subclinical atrial tachyarrhythmia — defined as an asymptomatic occurrence of atrial rate > 190 bpm for more than 6 minutes — was detected in 35% of study subjects over 2.5 years of observation; asymptomatic episodes far outnumbered symptomatic tachyarrhythmia. The risk for ischemic stroke in persons experiencing any atrial tachyarrhythmia was increased by 2.5 fold.

These data may help to explain some of the ischemic stroke cases that have no immediately visible antecedent. On the other hand, the complex terminology that separates AF into persistent, paroxysmal, subclinical, permanent, etc, may not be helpful; the phrase "once a fibber, always a fibber" simplifies the fact that (except for transient AF associated with peri-operative stress), any episode of AF, regardless of duration or extinguishability, elevates thrombotic risk.

Predicting Adverse Outcomes in Asthmatics: The Severity of Asthma Score

Source: Eisner MD, et al. Severity of asthma score predicts clinical outcomes in patients with moderate to severe persistent asthma. Chest 2012;141:58-65.

In the united states, approximately 5,000 persons die each year from asthma. Several metrics for predicting outcomes in asthmatics are available including the asthma control test, work productivity and impairment index-asthma, FEV1, and severity of asthma score (SOA). The SOA score is a validated questionnaire that incorporates asthma symptom frequency, medication use history, and hospitalizations for asthma among its 13 items. The Evaluating Clinical Effectiveness and Long-term Safety in Patients with Moderate-to-Severe Asthma study is an observational study of omalizumab or placebo in asthmatics with demonstrated inhalant allergen sensitivity. In the placebo arm (n = 2878), the SOA score was compared with the other metrics mentioned above for its ability to predict five asthma-related outcomes: exacerbations, hospitalizations, unscheduled office visits, emergency room visits, and need for systemic steroid treatment.

Of all the metrics chosen, SOA had the best predictive capacity, and was singular in that it had significant positive-predictive value for all five of the adverse asthma-related outcomes, whereas other tools were positively predictive in only a portion of the five outcomes. One of the attractive aspects of the SOA is that no special tools, lab tests, or measurements of pulmonary function are required to score it.

Real-life Use of Sunscreen in Ski Areas

Source: Buller DB, et al. Compliance with sunscreen advice in a survey of adults engaged in outdoor winter recreation at high-elevation ski areas. J Am Acad Dermatol 2012;66:63-70.

Current recommendations for sunscreen include three fundamental steps: 1) application up to 30 minutes before exposure, 2) use of a sun protection factor (SPF) of at least 15 (higher if ultraviolet [UV] radiation is high), and 3) reapplication every 2-3 hours. Skiing is associated with high UV exposure because of the combination of altitude and snow reflection.

Buller et al interviewed adult skiers in the western United States and Canada (n = 4837). Subjects were interviewed face-to-face while riding on chairlifts and gondolas (I don't ever remember getting offered one of those tough, technical scientific jobs!).

Almost 50% of subjects reported using sunscreen with SPF 15 or higher, and most applied it 30 minutes before sun exposure. Reapplication was only performed by 20%. Only 4% of respondents fulfilled all three components of appropriate sunscreen use. Overall, men were substantially less compliant than women.

Messages about the importance of skin protection appear to be reaching the public, including young athletic adults. Further education about the need for reapplication, coupled with insights about circumstances of increased exposure risk (like skiing), might improve compliance in the future.