Diagnostics

ECG

• Initial investigative study to confirm Afib

• To assess for evidence of risk factors that may affect treatment, such as:

  • Left ventricular hypertrophy

  • Bundle branch block

  • Preexcitation

  • Evidence of previous myocardial infarction

• CBC: assessment for anemia and signs of infection

• BMP

  • Serum electrolytes (Na+, K+, Mg2+, and Ca2+): to identify electrolyte imbalances

  • Serum glucose: to assess for hyperglycemia

  • BUN, serum creatinine: to identify chronic kidney disease (CKD)

• TSH, fT4: to screen for hyperthyroidism

• Liver chemistries: to assess for liver disease

• Consider also the following to evaluate for complications and underlying etiology:

  • Troponin levels: to assess for myocardial injury or infarction

  • Brain-natriuretic peptide (BNP) or NT-proBNP

  • D-dimer levels: if patients have risk factors (e.g., DVT) or clinical features of pulmonary embolism

  • Serum toxicology (e.g., ethanol level, digoxin level) and/or urine toxicology (e.g., cocaine, amphetamines)

Always assess for reversible causes of Afib, such as hyperthyroidism and electrolyte imbalances.

• Indications: all patients with new-onset Afib to assess cardiac function and rule out underlying structural cardiac disease (e.g., mitral valve stenosis)

  • For indications for TEE, see “Transesophageal echocardiogram for atrial fibrillation.”

• Findings

  • The heart may be structurally normal (more common in young people).

  • Left atrial thrombus may be visible

  • Atrial enlargement

  • Chaotic atrial movements that are not coordinated with ventricles

• Indication: to evaluate for pulmonary disease or heart failure

• Findings

  • Signs of heart failure, e.g., cardiomegaly and signs of pulmonary edema

  • Signs of an underlying etiology, such as pulmonary embolism, pneumonia, or COPD

• Options:

  • Inpatient: continuous cardiac telemetry

  • Outpatient/ambulatory: Holter monitor, event recorders, loop recorders

• Indications

  • Assess whether rate or rhythm control measures are adequate

  • Evaluate for suspected paroxysmal asymptomatic Afib

  • Assessment of the relationship between symptoms and Afib (patient-activated event recorders)

• Findings: episodes of paroxysmal Afib; may reveal additional arrhythmias, e.g., atrial flutter

Holter ECG monitoring should be used in ambulatory patients with risk factors and symptoms of arrhythmia to rule out paroxysmal Afib.

• Cardiac stress test: if underlying ischemic heart disease is suspected or to assess the adequacy of rate control

• Electrophysiological study: suspected preexcitation (delta wave on ECG), if there is suspicion for an underlying SVT triggering Afib, or to distinguish between ventricular tachycardia and Afib with aberrant conduction

• Sleep study: if obstructive sleep apnea is suspected

• Afib should be differentiated from other supraventricular tachyarrhythmias with a narrow QRS complex and tachyarrhythmias with wide QRS complexes .