Stroke Prevention by Screening for Atrial Fibrillation

Abstract & Commentary

By Harold L. Karpman, MD, FACC, FACP, Clinical Professor of Medicine, UCLA School of Medicine. Dr. Karpman reports no financial relationships relevant to this field of study.

Synopsis: Stepwise risk factor-stratified screening in an elderly population using a handheld ECG device detected a significant number of patients with silent paroxysmal atrial fibrillation.

Source: Engdahl J, et al. Stepwise screening of atrial fibrillation in a 75-year-old population: Implications for stroke prevention. Circulation 2013;127:930-937.

Atrial fibrillation (AF) is a common arrhythmia, and its prevalence is known to steeply increase with age reaching 6-8% of 75-year-old patients.1,2 Cardioemboli occur frequently in patients with AF, especially in those patients who have not been treated with oral anticoagulants, often resulting in ischemic stroke.3,4 Although AF is frequently symptomatic, unfortunately it also occurs asymptomatically quite frequently, especially when it occurs paroxysmally, and often, ischemic stroke can be the first clinical sign of the arrhythmia. AF is found to be present in 25-30% of patients sustaining an acute ischemic stroke.5-7 The clinical picture of ischemic stroke associated with AF is often particularly severe and it is more frequently fatal than ischemic strokes of other etiologies.5,8

Engdahl and his colleagues performed a study by screening for silent AF in an at-risk population of 75-to 76-year-old patients in the municipality of Halmstad, Sweden.10 The 848 participants received a 12-lead ECG. Those with sinus rhythm on the 12-lead ECG, no history of AF, and two or more risk factors according to the CHADS risk factor profile9 were invited to participate in a 2-week observation period and were given a handheld ECG and asked to record their ECG for 20-30 seconds twice daily routinely or at any other time if palpitations occurred. Among the 403 persons with two or more risk factors according to the CHADS risk factor classification9 who completed the handheld ECG event recording, 30 (7.4%) subjects were diagnosed with silent paroxysmal AF and, therefore, were candidates for starting oral anticoagulation therapy.

Commentary

Relatively recent advances in electronic technology have resulted in the ability to attach a very small, self-contained, inexpensive ECG device to the common mobile phone permitting ECG acquisition anywhere and at any time.11 These ECGs can be of any duration and can be instantaneously transmitted to any website. The current study has clearly demonstrated the utility of this device in detecting silent paroxysmal AF,10 which is known to occur in a significant percentage of the elderly population. Obviously, it would be better to detect paroxysmal AF and initiate anticoagulant therapy before a cerebrovascular accident (CVA) occurs since outpatient anticoagulant therapy has proven to be so successful in diminishing acute CVA occurrences in patients with paroxysmal or fixed AF. Therefore, the results of the study prove that short-term ECG monitoring with the patient-operated device can be a useful addition to other techniques such as a single 12-lead ECG, palpation of the pulse, Holter monitoring, etc. for detecting paroxysmal AF.

In summary, since patients with silent paroxysmal AF constitute the majority of the AF population, identifying and implementing the best technique for detecting silent AF is a crucial critical need to institute outpatient anticoagulant therapy prior to the occurrence of an acute cardioembolic CVA. Therefore, screening for silent AF in all elderly patients with one or more additional CHADS factors such as diabetes, hypertension, and/or congestive heart failure using a simple patient-operated ECG device attached to a cell phone should be considered for implementation by clinicians who have the capability to handle this relatively inexpensive, important patient service. Additional research studies are now in progress to determine whether this is the best screening technique for the early detection of silent AF. However, the results of these studies will not be available for at least several years and, as demonstrated by Engdahl and colleagues,10 we have an excellent inexpensive screening technique currently available and consideration should be given to putting it to use now.

References

1. Go AS, et al. JAMA 2001;285:2370-2375.

2. Naccarrelli GV, et al. Am J Cardiol 2009;104:1534-1539.

3. Olesen JB, et al. BMJ 2011;342:d124.

4. Hart RG, et al. Ann Intern Med 2007;146:857-867.

5. Indredavik B, et al. J Intern Med 2005;258:133-144.

6. Marini C, et al. Stroke 2005;36:1115-1119.

7. Rizos T, et al. Cerebrovas Dis 2011;32:276-282.

8. Saxena R, et al. Stroke 2001;32:2333-2337.

9. Gage BF, et al. JAMA 2001;285:2864-2870.

10. Engdahl J, et al. Circulation 2013;127:930-937.

11. Doliwa Sobocinski P, et al. Europace 2012;14:1112-1116.