ECG of the Week - 4th June 2018 - Interpretation

The following ECG is from an 81 yr old female who presented with a 4 day history of RUQ pain on a background of known gallstones. 

Click to enlarge

Rate:

• Mean ventricular rate 114 bpm

Rhythm:

• Irregular
• No p wave visible

Axis:

• Normal

Intervals:

• QRS - Normal (90ms)
• QT - 340ms (QTc Bazette 430 ms)

Additional:

• Low voltage QRS
• Flat T lead avL
• T waves in inferior leads relatively large in relation to QRS voltage
• No ST depression / elevation

Interpretation:

• Atrial fibrillation with rapid ventricular response
• Low voltage QRS

Clinical Factors in Atrial Fibrillation

There are several features to establish on assessment of the patient in atrial fibrillation that will influence both the immediate and long-term management strategies, including:

• Onset and duration of symptoms
• Likelihood of paroxysmal episodes
• Evidence of compromise from AF
• Chest pain, cardiac failure, hypotension etc.
• Current medications
• Especially anti-coagulation and anti-arrhythmics
• Potential precipitant / cause
• E.g. sepsis, electrolyte abnormality, endocrine disease
• Suitability and contra-indications to management options
• E.g. fasting status, anaesthetic risk, drug allergy / intolerance, bleeding risk

Management Options in Atrial Fibrillation

There are several considerations in the management of AF which include:

• Rate vs. rhythm control
• Electrical vs Chemical rhythm control
• Anti-coagulation
• Risk vs Benefit
• Drug to use
• ? Underlying precipitant
• Infection / ischaemia / structural / endocrine / metabolic etc.
• Follow-up / disposition
• Ablation suitability

Despite being one of the commonest arrhythmia encountered in medicine there is considerable variability in the clinical management of atrial fibrillation. There are a number of international guidelines and protocols regarding AF management, including:

• European Society of Cardiology Guidelines 2010
• American College of Cardiology Foundation / American Heart Association / Heart Rhythm Society Guidelines 2011 Update
• American College of Cardiology Foundation / American Heart Association / Heart Rhythm Society 2006 Guideline
• Canadian Cardiovascular Society Guidelines 2010
• NICE Guideline 2006
• Ottawa Aggressive Protocol for Recent Onset Atrial Fibrillation/Flutter
• Western Australia Cardiovascular Health Network Guidelines 2011 

AF Related Calculators (links to MDCalc)

• CHADS2 Score
• CHA2DS2-VASc Score
• HAS-BLED Score

Low Voltage QRS

Differentials include:

• Increased distance between heart and ECG leads
• Obesity
• Emphysema
• Pleural effusion
• Pericardial effusion
• Inflammatory / infiltrative disease
• Sarcoid
• Amyloid
• Myxoedema
• Scleroderma
• Structural
• Cardiomyopathy

What happened ?

This patient was commenced on metoprolol and digoxin for rate control as their time of onset was unknown. Their underlying cholecystitis was treated with fluids and antibiotics.

References / Further Reading

Life in the Fast Lane

• Atrial fibrillation
• Low Voltage

Textbook

• Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.