How should bradycardia be treated and managed?

Treatment and Management of Bradycardia

For symptomatic bradycardia, atropine 0.5-1 mg IV every 3-5 minutes (maximum 3 mg total) is first-line treatment, followed by epinephrine or dopamine infusions if atropine fails, with transcutaneous pacing as a bridge to definitive therapy; permanent pacemaker implantation is indicated only after excluding reversible causes and documenting symptom-rhythm correlation. 1

Critical First Step: Distinguish Symptomatic from Asymptomatic Bradycardia

Asymptomatic bradycardia requires no treatment regardless of heart rate. 1, 2, 3

• Asymptomatic sinus bradycardia (even <40 bpm) is common in athletes, during sleep, and in young healthy individuals due to high vagal tone 1, 2
• No minimum heart rate threshold exists below which treatment is automatically indicated—only symptom-rhythm correlation matters 2
• Asymptomatic patients should not receive atropine, chronotropic agents, monitoring, or pacemakers (Class III: Not Indicated) 1, 2, 4

Symptoms Requiring Immediate Intervention

Assess for these cardinal symptoms that indicate hemodynamically significant bradycardia:

• Syncope or presyncope (especially with trauma risk) 1, 2, 3
• Altered mental status (confusion, decreased responsiveness) 2, 3
• Ischemic chest pain/angina from reduced coronary perfusion 1, 2, 3
• Hypotension or shock (systolic BP <90 mmHg, cool extremities, end-organ hypoperfusion) 2, 3
• Acute heart failure (dyspnea, pulmonary edema, jugular venous distension) 1, 2, 3
• Fatigue and exercise intolerance (less specific but clinically relevant) 1, 2

Acute Management Algorithm for Symptomatic Bradycardia

Step 1: Immediate Stabilization

• Assess airway, breathing, oxygenation; provide supplemental oxygen if hypoxemic 3
• Establish IV access and continuous cardiac monitoring with blood pressure monitoring 3
• Obtain 12-lead ECG to identify mechanism (sinus bradycardia, AV block type, etc.) but do not delay treatment 3
• Verify symptoms are caused by bradycardia rather than bradycardia being a response to another condition 3

Step 2: Identify and Treat Reversible Causes (Class I Recommendation)

This is mandatory before considering permanent pacing. 1, 3, 4

Reversible Cause	Action
Medications (beta-blockers, calcium channel blockers, digoxin, antiarrhythmics, ivabradine)	Discontinue or reduce dose [1,3]
Hypothyroidism	Check TSH/free T4; treat with thyroxine replacement [1,2]
Electrolyte abnormalities (hyperkalemia, hypokalemia, hypomagnesemia)	Correct imbalances [1,2,3]
Acute myocardial infarction (especially inferior MI)	Treat ischemia; bradycardia often resolves [1,2]
Elevated intracranial pressure	Neuroimaging and neurosurgical consultation [1,2]
Obstructive sleep apnea	Sleep study if nocturnal bradycardia [1,2]
Severe acidosis or hypoglycemia	Correct metabolic derangement [1,3]

Step 3: Pharmacologic Treatment

First-line: Atropine 1, 3

• Dose: 0.5-1 mg IV bolus (doses <0.5 mg may paradoxically slow heart rate) 1, 2
• Repeat every 3-5 minutes as needed
• Maximum total dose: 3 mg 1, 3
• Most effective for sinus bradycardia and AV nodal blocks; less effective for infranodal (wide-complex) blocks 2
• Contraindication: Heart transplant patients (may cause paradoxical high-degree AV block due to lack of autonomic innervation) 1, 2

Second-line: Catecholamine Infusions (if atropine fails) 1, 3

• Epinephrine: 2-10 µg/min IV infusion 1
• Dopamine: 2-10 µg/kg/min IV infusion 1, 3
• Alternative agents: isoproterenol, dobutamine 3

Special circumstances:

• After inferior MI, cardiac transplant, or spinal cord injury: Consider theophylline 100-200 mg slow IV (maximum 250 mg) 1

Step 4: Temporary Pacing

Transcutaneous pacing 1, 2, 3

• Indicated when atropine fails and hemodynamic compromise persists
• Serves as bridge to transvenous or permanent pacing
• Important caveat: No more effective than second-line drug therapy in most cases 1
• Painful and less reliable than transvenous pacing 3

Transvenous pacing 2, 3

• Indicated for persistent hemodynamic instability refractory to medical therapy
• More reliable than transcutaneous but higher complication rate (14-40%): venous thrombosis, pulmonary emboli, arrhythmias, perforation 2
• Use as bridge to permanent pacemaker or until reversible cause resolves 2, 3

Indications for Permanent Pacemaker

Class I (Strongly Recommended)

Permanent pacing is indicated when: 1, 2, 3

• Symptomatic bradycardia persists after excluding/treating reversible causes 1, 2, 3
• Symptomatic bradycardia results from necessary guideline-directed medical therapy with no alternative treatment 1, 2
• High-grade AV block (second-degree Mobitz II or third-degree) with symptoms 1, 2

Class IIa (Reasonable)

• Tachy-brady syndrome with symptoms attributable to bradycardia 2
• Symptomatic chronotropic incompetence (inadequate heart rate response to exercise) 1, 2

Class IIb (May Be Considered)

• Chronically low resting heart rate <40 bpm while awake in minimally symptomatic patients 2

Class III (Not Indicated)

• Asymptomatic sinus node dysfunction 1, 2, 4
• Symptoms clearly present without accompanying bradycardia 2
• Physiologic bradycardia in athletes or during sleep 1, 2, 4

Diagnostic Workup for Intermittent Symptoms

When symptoms are intermittent, document rhythm-symptom correlation before permanent pacing: 1, 2

Symptom Frequency	Monitoring Strategy
Daily or near-daily	24-72 hour Holter monitor [1,2]
Weekly	7-30 day event recorder [1,2]
Monthly or less	Implantable loop recorder (diagnostic yield 43-50% at 2 years, 80% at 4 years) [2]

Electrophysiology study (EPS): 2

• Not indicated in asymptomatic patients (Class III) 2
• May be considered (Class IIb) when symptoms present but non-invasive testing non-diagnostic 2
• Higher yield in patients with structural heart disease or abnormal baseline ECG 2

Pacing Mode Selection

For sinus node dysfunction with intact AV conduction: 2, 4

• Atrial-based pacing preferred over single-chamber ventricular pacing (Class I) 2, 4
• Dual-chamber or single-chamber atrial pacing recommended 2, 4

For AV block: 2

• Dual-chamber pacing typically required

Special Populations and Pitfalls

Elderly Patients (Age ≥70 years)

• Age alone is not a contraindication to pacing if symptomatic and reversible causes excluded 1, 2
• Consider functional status, life expectancy, and quality-of-life priorities in shared decision-making 1, 2
• Goals-of-care discussion essential before device implantation 2

Athletes and Physiologic Bradycardia

• Resting rates of 40-50 bpm (awake) and 30 bpm (sleep) are normal 2
• Occasional sinus pauses or first-degree AV block during sleep are benign 2
• Do not confuse physiologic sinus bradycardia with pathologic bradyarrhythmias 2

Heart Transplant Recipients

• Atropine contraindicated (Class III: Harm) due to risk of paradoxical high-degree AV block from denervated heart 1, 2
• Use catecholamine infusions or pacing instead 1

Common Pitfalls to Avoid

1. Treating asymptomatic bradycardia based solely on heart rate number 1, 2, 4
2. Implanting permanent pacemaker before adequately evaluating reversible causes 1, 3, 4
3. Using atropine doses <0.5 mg (may paradoxically worsen bradycardia) 1, 2
4. Administering atropine to heart transplant patients 1, 2
5. Failing to document symptom-rhythm correlation before permanent pacing 1, 2
6. Unnecessary monitoring or admission for asymptomatic patients 1, 2

Prognosis

• Asymptomatic sinus bradycardia: Benign prognosis, does not affect survival 2
• Symptomatic sinus node dysfunction: High risk of cardiovascular events if untreated 2
• Chronotropic incompetence: Associated with increased cardiovascular and overall mortality 2
• Acute symptomatic bradycardia: 30-day mortality approximately 5% in emergency department cohorts; 50% require permanent pacing 5