Bradycardia or atrioventricular block found
BioMG follows French guidelines. Adapt it to the guidelines and the tests available where you practise.
Well-tolerated bradycardia or AV block: look for a reversible cause
In the practice
- 12-lead ECG; review the prescription (bradycardia-inducing drugs).
Laboratory tests
- Serum electrolytes (potassium)
- TSH
- Serum calciumif needednon-French guidelineElectrolyte disturbances (potassium, calcium, magnesium) are among the extrinsic causes of bradycardia in ESC [2]; ESC lists hypercalcaemia among the causes to look for when there are suggestive features [2].
- Serum magnesiumif needednon-French guidelineElectrolyte disturbances (potassium, calcium, magnesium) are among the extrinsic causes of bradycardia in ESC [2]; ESC lists hypercalcaemia among the causes to look for when there are suggestive features [2].
- Serum digoxin (if on digoxin)if needednon-French guidelinePatient on digoxin: ESC lists digitalis level among the useful tests when a secondary cause is suspected [2].
- Lyme serology (AV block without known heart disease, tick exposure in the last 6 months)if neededAV block in a young person, especially after tick exposure or erythema migrans: ESC lists Lyme serology for the diagnosis of myocarditis [2]. Lyme carditis is among the infectious causes of atrioventricular conduction disorder [2]. HAS (2025) indicates serology for any AV block (1st, 2nd or 3rd degree) without identified predisposing heart disease, with tick exposure in the previous 6 months, and then asks for cardiology advice (grade AE) [3].
Also consider
Poorly tolerated bradycardia or syncope
- Ongoing malaise, hypotension, chest pain, dyspnoea, confusion: call 15 (French emergency medical service). Do not delay for tests in the community.
- Recent loss of consciousness with AV block or bradycardia on ECG: cardiology opinion within 24 hours.
Sources (8)
- Assurance maladie. Cartographie des pathologies et des dépenses, effectifs 2024 (data.ameli.fr, jeu « effectifs »), consulté le 24/10/2026.
- Glikson M, Nielsen JC, Kronborg MB, et al. 2021 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy. Eur Heart J. 2021;42(35):3427-3520.
- Haute Autorité de santé. Borréliose de Lyme et autres maladies vectorielles à tiques (MVT). Recommandation de bonne pratique, février 2025 (sections 2.6 et 4.3.5).
- National Institute for Health and Care Excellence (NICE). Transient loss of consciousness ('blackouts') in over 16s. Clinical guideline CG109, août 2010, mise à jour 21 novembre 2023.
- Kusumoto FM, Schoenfeld MH, Barrett C, et al. 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay. J Am Coll Cardiol. 2019;74(7):e51-e156.
- Hawks MK, Paul MLB, Malu OO. Sinus node dysfunction. Am Fam Physician. 2021;104(2):179-185.
- National Institute for Health and Care Excellence (NICE). Lyme disease. Guideline NG95, avril 2018, mise à jour 17 octobre 2018.
- Landelijke Coördinatie Infectieziektebestrijding (LCI), RIVM (Pays-Bas). Richtlijn Lymeziekte. Septembre 2013, présentation revue le 18 mars 2025 (la page signale une durée de validité dépassée).