The diagnosis of and appropriate treatment of atrial fibrillation to prevent stroke is an important topic for all clinicians. So below are two new resources that address this difficult problem [for a list of more posts on “atrial fibrillation” type the term into the Search box on this blog. See also my post “Should We Screen For Atrial Fibrillation“].
There is a new American Heart Association Scientific Statement:
Atrial Fibrillation Burden: Moving Beyond Atrial Fibrillation as a Binary Entity: A Scientific Statement From the American Heart Association [PubMed Abstract] [Full Text HTML] [Free Full Text PDF Download]. Circulation. 2018 Apr 16. pii: CIR.0000000000000568. doi: 10.1161/CIR.0000000000000568. [Epub ahead of print].
What follows below is from the American College of Cardiology‘s Latest in Cardiology, [Points To Remember About the new AHA Scientific Statement above]:
The following are key points to remember from this American Heart Association (AHA) Scientific Statement about atrial fibrillation (AF) burden, and how it may be associated with clinical outcomes:
- Current guidelines define the presence of AF as electrocardiographic documentation of absolutely irregular RR intervals and no discernible, distinct P waves lasting for at least 30 seconds. There are many ways one can define AF burden, such as the duration of the longest AF episode, number of AF episodes, or the percentage of time the patient is in AF during a certain monitoring period.
- Most published studies evaluated AF in a binary fashion (present or absent) and have not investigated AF burden.
- Current guidelines recommend using vascular risk factors (as measured by the CHA2DS2-VASc score) and do not consider AF burden when making decisions regarding anticoagulation for stroke prevention in AF. While data are mixed, the strongest contemporary evidence suggests that patients with persistent AF are at a higher risk of stroke than those with paroxysmal AF.
- AF burden may be assessed in patients who have an implanted dual-chamber cardiac implantable electronic device (CIED) – pacemaker or implantable cardioverter-defibrillator (ICD). Implantable loop recorders and single-chamber ICDs rely on R-R intervals for arrhythmia detection and have lower sensitivity and specificity for AF identification than dual-chamber CIEDs.
- Data from CIEDs suggest that even relatively short AF episodes (>5 to 6 minutes) are associated with an increased risk of stroke. Interestingly, among patients with CIEDs, the majority of ischemic strokes are temporally discordant from AF episodes. It is unknown whether there is a threshold of AF burden that results in an increased risk of stroke.
- AF is also associated with nonstroke outcomes such as heart failure (HF), cognitive impairment and dementia, myocardial infarction, chronic kidney disease progression to end-stage renal disease, sudden cardiac death, and all-cause death.
- Physical inactivity, obesity, and hypertension have all been linked to increased incidence of AF; however, the degree to which atherosclerotic and lifestyle factors contribute to AF burden is not well established.
- Weight loss and maintaining a healthy weight are effective in reducing AF burden. Published data regarding whether intensive blood pressure lowering would reduce AF burden are lacking. Randomized clinical trials are needed to determine whether interventions to manage stress (e.g., yoga, mindfulness meditation) would reduce AF burden.
- The concept of temporal AF burden aggregation, or AF density, has been proposed. AF density is defined as the absolute cumulative deviation of the patient’s actual burden development from the hypothetical uniform burden development divided by the minimum time required for development of all AF episodes. Given the same AF burden, a patient with a small number of prolonged episodes of AF has a higher AF density than a patient with many brief episodes of AF.
- Developments in monitoring technologies will likely allow better definition of the significance of changes in AF burden over time.
