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Peripheral Artery Disease: causes and consequences

Coronary Artery Disease: causes and consequences

Introduction to Atrial Fibrillation

This section covers the clinical presentation, classification and origin of AF, and its management

  • In AF the atria beat irregularly and often rapidly, as a result, the ventricles cannot adequately fill with blood, cardiac output is reduced and a thrombus can form from stagnant blood in the fibrillating left atrium
  • AF can present with a variety of symptoms (listed below), which can be mild to severe in severity, but some patients have no symptoms at all:
    • Fatigue
    • Palpitations
    • Syncope/dizziness
    • Angina/chest pains
    • Dyspnoea/breathlessness
    • Stroke/transient ischaemic attack
  • AF has a heterogeneous clinical presentation, occurring in the presence or absence of detectable heart disease or related symptoms; therefore, clinical guidelines feature recommendations for appropriate classification/definition
  • AF is classified into five categories, as summarized in the Table below:1,2
Recommendations for classification of AF, based on a consensus document by the European Society of Cardiology2, the American College of Cardiology and the American Heart Association1
Classification Clinical presentation
First diagnosed AF
  • AF that has not been diagnosed before, irrespective of the duration of the arrhythmia or the presence and severity of AF-related symptoms
Paroxysmal
  • Spontaneous/self-terminating or with intervention
  • Episode duration: ≤7 days and most often <48 hours
Persistent
  • Sustained/not self-terminating
  • Episode duration: >7 days
Long-standing persistent
  • Continuous AF lasting for ≥1 year when it is decided to adopt a rhythm control strategy
Permanent
  • AF that is accepted by the patient (and physician)
  • Rhythm control interventions, by definition not pursued
  • Definitions of NVAF and VAF remain a matter of debate; current definitions are summarized in the table below
  • Classification of AF as VAF or NVAF facilitates identification of risk for thromboembolic events and the need for a specific antithrombotic strategy3
Current guideline definitions for NVAF and VAF
Origin of AFDefinition according to guidelines
NVAFAF in the absence of rheumatic mitral stenosis, a mechanical or bioprosthetic heart valve, or mitral valve repair1
VAFAF related to rheumatic valvular disease (predominantly mitral stenosis) or mechanical heart valves2

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Diagnosing atrial fibrillation from ECGs
Atrial fibrillation (AF) is most commonly diagnosed on the basis of an irregular electrocardiogram (ECG). Here, we review some of the key hallmarks of AF using example patient ECGs (provided by Dr Joe Martins and Dr Ron Pisters)
Approval Number: PP-XAR-ALL-0224-1

Because AF is frequently intermittent and can be asymptomatic or associated with non-specific symptoms, detection and diagnosis can be difficult.

 

Investigations for the clinical evaluation of AF include4

  • ECG: Upon detection of an irregular pulse, an ECG should be performed in all cases of suspected AF, whether symptomatic or not
    • With suspected paroxysmal AF, a 24-hour ambulatory ECG monitor should be used if asymptomatic episodes are suspected or if episodes are <24 hours apart
    • An event recorder ECG should be used where symptomatic episodes are >24 hours apart
  • Echocardiograms: to assess the dimensions of the left atrium and left ventricle and left ventricular wall thickness and function, and to exclude occult valvular or pericardial disease and hypertrophic cardiomyopathy
    • TTE: performed in patients with AF when:
      • A baseline echocardiogram is important for long-term management
      • A rhythm-control strategy that includes cardioversion (electrical or pharmacological) is being considered
      • There is a high risk or a suspicion of underlying structural/functional heart disease that influences subsequent management
      • Refinement of clinical risk stratification for antithrombotic therapy is needed
    • TEE: performed in patients with AF when:
      • TTE demonstrates an abnormality (such as valvular heart disease) that warrants further specific assessment
      • TEE-guided cardioversion is being considered
  • Blood tests are important for first episodes of AF and when the ventricular rate is difficult to control – these include tests of thyroid, renal and hepatic function
  • Subsequent sections consider how management approaches differ according to the type of AF and specific patient characteristics.
    • In general, management of patients with AF involves three main objectives, which are not mutually exclusive:1,2
      • Rate control
      • Prevention of thromboembolism
      • Correction of rhythm disturbance
    • To find out more about the potentially serious consequences of AF and the critical nature of its management, click on the link to next section below

 

Next section: Preventing AF-Related Stroke

References

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