Which lab studies are indicated following the diagnosis of atrial fibrillation (Afib) (AF)?

Updated: Nov 18, 2019
  • Author: Lawrence Rosenthal, MD, PhD, FACC, FHRS; Chief Editor: Jeffrey N Rottman, MD  more...
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Laboratory studies in patients with atrial fibrillation (AF) are aimed at uncovering underlying disorders, which may be particularly important to address when ventricular rate is difficult to control. One study suggests that minor elevations in troponin I levels upon hospital admission is associated with higher mortality and cardiac events, which may be useful for risk stratification. [52]

Laboratory studies indicated include the following:

  • Complete blood cell (CBC) count (looking for anemia, infection)

  • Levels of serum electrolytes and blood urea nitrogen (BUN)/creatinine (looking for electrolyte disturbances or renal failure)

  • Cardiac enzymes levels: Creatine kinase (CK) and/or troponin level (to investigate myocardial infarction as a primary or secondary event)

  • B-type natriuretic peptide (BNP) level (to evaluate for congestive heart failure)

  • D-dimer level (if the patient has risk factors to merit a pulmonary embolism workup)

  • Thyroid function studies (to assess for thyrotoxicosis, a rare, but not-to-be-missed, precipitant)

  • Digoxin level (may be obtained when appropriate for toxicity; generally considered safe to give digoxin to patient with AF on digoxin for rate control without waiting for lab values if patient presents with AF with rapid ventricular response [RVR])

  • Toxicology testing or ethanol level

Relatively recent studies indicate that increased plasma trimethylamine-N-oxide (TMAO) levels are associated with incident AF independent of traditional AF risk factors and of dietary choline intake. [53] More studies are needed to evaluate endogenous metabolic factors that impact the relationship between TMAO and cardiovascular disease.

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