Sinus Bradycardia Workup

Updated: Dec 27, 2017
  • Author: Mark W Livingston, MD; Chief Editor: Erik D Schraga, MD  more...
  • Print

Laboratory Studies

Laboratory studies may be helpful if the cause of the bradycardia is thought to be related to electrolytes, drug, or toxins. In cases of sick sinus syndrome, routine laboratory studies are rarely of specific value.

Reasonable screening studies, especially if the patient is symptomatic and this is the initial presentation, include the following:

  • Electrolyte levels

  • Glucose level

  • Calcium level

  • Magnesium level

  • Thyroid function tests

  • Toxicologic screen

  • Troponin


Imaging Studies

Routine imaging studies are rarely of value in the absence of specific indications.


A 12-lead ECG may be performed to confirm the diagnosis.

In a study that evaluated normative ECG characteristics and the prevalence of abnormal ECG findings among competitive rowers, Wasfy et al reported that in 94% of the rowers, training-related 12-lead ECG findings included sinus arrhthmia in 55%, sinus bradycardia in 51%, and incomplete right bundle branch block in 42%. [5] Significant sex differences included isolated voltage criteria for left ventricular hypertropher and early repolarization pattern occurring more in men than women. The investigators noted that depending on the ECG criteria used (eg, 2010 European Society of Cardiology [ESC], 2013 "Seattle criteria"), the classification and diagnostic accuracy of an abnormal ECG may be affected. [5]