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Anticoagulation Therapy for Stroke Prevention

AF screening and diagnosis

Read time: 60 mins
Last updated:16th Jun 2022
Published:24th Nov 2021

Early detection and management of atrial fibrillation (AF) is crucial for stroke prevention. Join our expert Professor John Camm to discover:

  • The latest screening technology for identifying AF
  • The gold standard for AF diagnosis
  • How AF risk factors should be managed

Atrial fibrillation symptoms

Atrial fibrillation (AF) patients can present with a wide range of symptoms; however, these can be non-specific and a poor guide for AF diagnosis

AF patients may present with heart failure, myocardial infarction or another acute coronary syndrome (ACS), stroke or haemodynamic collapse, and a variety of other typically non-specific symptoms (Figure 1)1.

PFI_Stroke_Fig7.png

Figure 1. Common atrial fibrillation symptoms (Adapted2).

However, 12% to 33% of AF patients are asymptomatic3,4. On the other hand, AF patients often experience debilitating symptoms despite treatment (Figure 2)3.

PFI_Stroke_Fig8.png

Figure 2. Prevalence of atrial fibrillation symptoms despite treatment (Adapted2).

Women tend to experience worse AF symptoms

Women tend to develop more frequent and severe AF symptoms than men.

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Atrial fibrillation screening

Professor John Camm (London, UK) discusses the importance of detecting atrial fibrillation (AF) early.

Asymptomatic AF is associated with increased risk of stroke and mortality compared with symptomatic AF6. Observational data suggest that screen-detected AF responds to treatment similarly to AF detected by routine care7.

Therefore, international initiatives to implement screening for AF in clinical practice are increasing. This is not only due to high prevalence of asymptomatic AF, but also to the overall increasing AF prevalence, previously unknown AF detection in about 10% of all ischaemic strokes, potential to prevent AF-related strokes with appropriate management, and increasing availability of screening tools2.

Atrial fibrillation screening tools

The tools that can be used for AF screening are:

  • Patient- or healthcare professional-initiated oscillometric blood pressure cuff
  • Pulse auscultation
  • Patient-initiated photoplethysmogram on smartphone
  • Semicontinuous photoplethysmogram on a smartwatch or wearable device
  • Patient- or healthcare professional-initiated intermittent electrocardiogram (ECG) rhythm strip using smartphone or dedicated connectable device
  • Intermittent smartwatch ECG initiated by semi-continuous photoplethysmogram with prompt notification of irregular rhythm or symptoms
  • Wearable belts for continuous recording
  • Stroke unit/in hospital telemetry monitoring
  • Long-term Holter
  • 1–2 week continuous ECG patches
  • Implantable cardiac monitors

Regardless of the tool used, when AF is detected by screening, a single-lead ECG tracing of ≥ 30 s or 12-lead ECG showing AF analysed by a physician with expertise in ECG rhythm interpretation is necessary to establish a definitive diagnosis of AF.

The Apple Heart and the Huawei Heart Studies on atrial fibrillation

The Apple Heart study8 included 419, 297 self-enrolled smartwatch app users (mean age 40 years) in the USA, of whom 0.5% received an irregular pulse notification (0.15% of those aged <40 years, 3.2% among those aged >65 years). Subsequent 1-week ECG patch monitoring revealed AF in 34% of monitored participants

The Huawei Heart study9 included 187, 912 individuals (mean age 35 years, 86.7% male), of whom 0.23% received a ‘suspected AF’ notification. Of those followed up, 87.0% were confirmed as having AF, with the positive predictive value of photoplethysmography signals being 91.6% [95% confidence interval (CI) 91.5 - 91.8]. Of those with identified AF, 95.1% entered an integrated AF management programme using a mobile AF App (mAFA).

Risks and benefits of atrial fibrillation screening

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Atrial fibrillation diagnosis

Electrocardiogram (ECG) monitoring remains the gold-standard method for diagnosing atrial fibrillation (AF).

The diagnosis of AF requires rhythm documentation with ECG tracing showing AF. By convention, an episode lasting at least 30 s is diagnostic for clinical AF2

Clinical and subclinical atrial fibrillation

Clinical AF can be symptomatic or asymptomatic and it is defined as AF documented by surface ECG.

Subclinical AF or atrial high-rate episodes (AHRE) refer to individuals without symptoms attributable to AF, in whom clinical AF is not previously detected (no surface ECG tracing of AF). Subclinical AF or AHRE are usually detected by implanted devices and wearables.

Clinical atrial fibrillation types

An irregular pulse should raise a suspicion of AF: the sensitivity and specificity of pulse rate for AF is 94% and 72%, respectively1,4. Clinical presentation (Table 2) may indicate the type of AF, although about a third of AF episodes are asymptomatic2,4.

Table 2. Presentation of different clinical types of atrial fibrillation (Adapted2). AF, atrial fibrillation.

Stroke prevention_T2_Table2.png

An ECG is the gold-standard method to diagnose AF (Figure 4)4. In addition, all AF patients should undergo a comprehensive evaluation, including accurate history, clinical examination and assessment of comorbidities and risk factors2.

AF screening and diagnosis_Fig3.png

Figure 4. Electrocardiogram showing normal sinus rhythm, atrial fibrillation, and differential diagnoses (Adapted12).

Typically, ECGs of AF typically do not show a distinct P wave1,5. Rather the electrical activity is disorderly (fibrillatory) with irregular R-R intervals1,5. Heartbeat is erratic and rapid, typically 90–170 beats per minute, reflecting the irregular ventricular activation. Unless the patient has other cardiac conduction disorders, the QRS complex tends to be narrow1. Clinicians should consider Holter monitoring (using a portable device for 24 to 48-hour cardiac monitoring) in patients presenting with palpitations13.

Atrial fibrillation diagnostic recommendation

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Atrial fibrillation comorbidities and risk factors

Professor John Camm (London, UK) discusses the management of risk factors for atrial fibrillation (AF).

Several comorbidities and risk factors contribute to AF and the risk of stroke. These modifiable comorbidities and risk factors seem to promote AF development and maintain the arrhythmia (Figure 7)5.

AF screening and diagnosis_Stroke_Fig7.png

Figure 7. Examples of modifiable comorbidities that seem to promote atrial fibrillation development and maintain the arrhythmia (Adapted5).

For instance, AF is associated with a 3-fold increase in the likelihood of developing congestive heart failure (CHF) and the prevalence increases with worsening New York Heart Association (NYHA) functional class. CHF risk is higher in people with permanent AF than those with persistent AF. In turn, CHF risk is higher in people with persistent than paroxysmal AF.

Patients with AF and CHF show a poorer prognosis than with either alone5

Therefore, risk factor modification is an important component of AF management5. For instance, a study that followed patients for 5 years after experiencing an AF-related stroke, reported that statins reduced mortality by 48%16.

More on treatment goals and strategies for AF

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References

  1. Gutierrez C, Blanchard DG. Diagnosis and treatment of atrial fibrillation. Am Fam Physician. 2016;94(6):442–452.
  2. Hindricks G, Potpara T, Dagres N, Arbelo E, Bax JJ, Blomström-Lundqvist C, et al. 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation developed in collaboration with the European Association for Cardio-Thoracic Surgery (EACTS): The Task Force for the diagnosis and management of atrial fibrillation of the European Society of Cardiology (ESC) Developed with the special contribution of the European Heart Rhythm Association (EHRA) of the ESC European Heart Journal. 2021;42(5):373–498.
  3. Zoni-Berisso M, Lercari F, Carazza T, Domenicucci S. Epidemiology of atrial fibrillation: European perspective. Clin Epidemiol. 2014;6:213–220.
  4. Dilaveris PE, Kennedy HL. Silent atrial fibrillation: Epidemiology, diagnosis, and clinical impact. Clin Cardiol. 2017;40(6):413–418.
  5. Rogers PA, Bernard ML, Madias C, Thihalolipavan S, Mark Estes NA, Morin DP. Current evidence-based understanding of the epidemiology, prevention, and treatment of atrial fibrillation. Curr Probl Cardiol. 2018;43(6):241–283.
  6. Potpara TS, Polovina MM, Marinkovic JM, Lip GYH. A comparison of clinical characteristics and long-term prognosis in asymptomatic and symptomatic patients with first-diagnosed atrial fibrillation: the Belgrade Atrial Fibrillation Study. International journal of cardiology. 2013;168(5):4744–4749.
  7. Martinez C, Katholing A, Freedman SB. Adverse prognosis of incidentally detected ambulatory atrial fibrillation. Thrombosis and Haemostasis. 2014;112(2):276–286.
  8. Turakhia MP, Desai M, Hedlin H, Rajmane A, Talati N, Ferris T, et al. Rationale and design of a large-scale, app-based study to identify cardiac arrhythmias using a smartwatch: The Apple Heart Study. American Heart Journal. 2019;207:66–75.
  9. Guo Y, Wang H, Zhang H, Liu T, Liang Z, Xia Y, et al. Mobile Photoplethysmographic Technology to Detect Atrial Fibrillation. Journal of the American College of Cardiology. 2019;74(19):2365–2375.
  10. Lown M, Garrard J, Irving G, Edwards D, Hobbs FR, Mant J. Should we screen for atrial fibrillation? The British journal of general practice : the journal of the Royal College of General Practitioners. 2017;67(660):296–297.
  11. Turakhia MP, Shafrin J, Bognar K, Goldman DP, Mendys PM, Abdulsattar Y, et al. Economic Burden of Undiagnosed Nonvalvular Atrial Fibrillation in the United States. The American journal of cardiology. 2015;116(5):733–739.
  12. Atrial Fibrillation - Cardiology - Highland Hospital - University of Rochester Medical Center. https://www.urmc.rochester.edu/highland/departments-centers/cardiology/conditions/atrial-fibrillation.aspx. Accessed 5 November 2021.
  13. Amarenco P, Bogousslavsky J, Caplan LR, Donnan GA, Hennerici MG. Classification of stroke subtypes. Cerebrovasc Dis. 2009;27(5):493–501.
  14. Contractor T, Khasnis A. Left atrial appendage closure in atrial fibrillation: A world without anticoagulation? Cardiol Res Pract. 2011;2011:752808.
  15. Reiffel JA, Verma A, Kowey PR, Halperin JL, Gersh BJ, Wachter R, et al. Incidence of previously undiagnosed atrial fibrillation using insertable cardiac monitors in a high-risk population: The REVEAL AF Study. JAMA Cardiol. 2017;2(10):1120–1127.
  16. Hayden D, Hannon N, Callaly E, Ní Chróinín D, Horgan G, Kyne L, et al. Rates and determinants of 5-year outcomes after atrial fibrillation–related stroke. Stroke. 2015;46(12):3488–3493.
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