Bradycardia

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

haemodynamically unstable

1st line – pharmacotherapy

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1st line –

pharmacotherapy

In patients with systemic hypotension, signs of cerebral hypoperfusion, progressive heart failure, angina, or life-threatening ventricular tachyarrhythmia, medical therapy should be started immediately until temporary cardiac pacing is initiated.

The most common medicines used to increase ventricular rate are intravenous atropine and adrenaline (epinephrine). All drugs are only marginally effective in providing sustained chronotropic support. Dobutamine can also be considered, especially when there is evidence of concomitant systolic heart failure.

Atropine should not be used in patients who have had a heart transplant or have acute spinal cord injury; use theophylline or aminophylline instead.[11]

Their efficacy is limited to patients with sinus node dysfunction or conduction abnormalities at the level of the atrioventricular (AV) node. However, patients with infranodal conduction system disease may demonstrate further worsening bradycardia.

Address underlying cause where one can be identified (e.g., prescription drug toxicity).

Primary options

atropine: 0.5 to 1 mg intravenously as a bolus, repeat every 3-5 minutes as needed, maximum 3 mg total dose

Secondary options

adrenaline (epinephrine): 2-10 micrograms/min intravenous infusion initially, titrate rate according to response

dobutamine: 0.5 to 1 micrograms/kg/min intravenous infusion initially, titrate rate according to response, maximum 20-40 micrograms/kg/min

aminophylline: consult specialist for guidance on dose

theophylline: consult specialist for guidance on dose

Consider – temporary pacing

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Consider –

temporary pacing

Additional treatment recommended for SOME patients in selected patient group

Patients who are not responsive to medical therapy require prompt temporary pacing. The two most commonly used modes of temporary pacing are transcutaneous and transvenous.

Transcutaneous pacing can be applied rapidly through external adhesive electrodes. However, this pacing modality usually serves as a bridge to transvenous pacing because it causes painful skeletal muscle stimulation and usually requires sedation. Furthermore, the efficacy of transcutaneous pacing to provide stable ventricular capture is limited to 78% to 94%.[54][55] It can be used as a sole temporary pacing modality to provide back-up in some patients with transient, infrequent, and short-lived episodes of bradycardia until a reversible cause is corrected or a permanent pacemaker is implanted.

Transvenous pacing is the most secure and effective modality for patients who require continuous temporary pacing. The temporary pacing lead is usually placed in the right ventricle or, rarely, in the right atrium or both chambers using one of the central veins (femoral, subclavian, or internal jugular). A mechanical prosthetic tricuspid valve is a contraindication to right ventricular pacing. Complications are common (up to 20%) and relate most commonly to venous access, infection, thromboembolism, heart perforation, or lead dislodgement. Ideally, pacing should not exceed more than a few days because of the incremental risk of infection.[54][55]

haemodynamically stable: sinus node dysfunction

reversible cause: asymptomatic or mild symptoms

1st line – treatment of underlying cause

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1st line –

treatment of underlying cause

For mild symptoms or when sinus node dysfunction is a result of a reversible or isolated cause (e.g., specific medicine, electrolyte disorder, or vasovagal event, such as taking blood), hospitalisation is usually unnecessary.

Underlying cause should be addressed (e.g., ceasing drug treatment, administration of electrolytes, or correction of thyroid dysfunction).

Consider – theophylline

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Consider –

theophylline

Additional treatment recommended for SOME patients in selected patient group

Theophylline may be used in selected patients with mild symptoms, such as predominantly exertional dizziness and/or fatigue.[56][57]

Primary options

theophylline: 200-400 mg orally (sustained-release) twice daily

reversible cause: severe symptoms

1st line – treatment of underlying cause + temporary pacing

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1st line –

treatment of underlying cause + temporary pacing

Temporary pacing is needed if there are severe symptoms or sequelae, including syncope, near-syncope, hypotension, marked fatigue, or ventricular arrhythmias (including torsades de pointes).

Underlying causes should be corrected and include specific medication, electrolyte disorder, vasovagal events, and thyroid dysfunction.

Atrial-based (AAI), ventricle-based (VVI), and dual chamber (DDD) pacing modes are all useful in correcting bradycardia caused by sinus node dysfunction, although the optimal pacing mode remains controversial. Nonetheless, growing evidence indicates that AAI, which avoids pacing of the ventricle, is associated with a relatively lower risk of atrial fibrillation and heart failure.[11][58]

Because patients with sinus node disease are at risk of developing atrioventricular block or atrial fibrillation, DDD pacemakers incorporating algorithms that enable minimising ventricular pacing (functional AAI pacing) are preferred over the single-lead AAI system.[59][60]

Accumulating evidence suggests that right ventricular pacing in patients with systolic left ventricular dysfunction may be associated with an increased risk of atrial fibrillation, worsening heart failure, and mortality secondary to left ventricular desynchronisation. Therefore, pacing of the ventricle should be avoided.[58][61] Dual-chamber pacemakers incorporating algorithms that enable the minimisation of ventricular pacing (functional AAI pacing) are preferred in patients with systolic left ventricular dysfunction.[62]

non-reversible cause: asymptomatic or mild symptoms

1st line – reassurance

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1st line –

reassurance

No specific treatment is required, and patients can be reassured about their condition.

non-reversible cause: severe symptoms

1st line – permanent pacing

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1st line –

permanent pacing

Acute treatment is needed if there are severe symptoms or sequelae, including syncope, near-syncope, hypotension, marked fatigue, or ventricular arrhythmias (including torsades de pointes). The role of pharmacotherapy is limited in this situation, and permanent pacing is the treatment of choice.

If patients have indications for permanent pacing, but also have indications for an implantable cardioverter defibrillator (ICD) such as systolic left ventricular dysfunction, they need to be evaluated for possible placement of an ICD with pacing capabilities.

haemodynamically stable: acquired atrioventricular block

reversible cause: asymptomatic without indications for pacing

1st line – treatment of underlying cause

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1st line –

treatment of underlying cause

The underlying cause should be addressed (e.g., ceasing drug treatment, administration of electrolytes, or correction of thyroid dysfunction).

reversible cause: symptomatic or indications for pacing

1st line – treatment of underlying cause + temporary pacing

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1st line –

treatment of underlying cause + temporary pacing

The underlying cause should be addressed (e.g., ceasing drug treatment, administration of electrolytes, or correction of thyroid dysfunction).

Temporary pacing should be considered when any of the following is present: high-grade atrioventricular (AV) block, Mobitz type II second-degree AV block, third-degree AV block, or evidence of infranodal block, regardless of symptoms. After correction of reversible causes, re-assessment of AV conduction should be performed before a clinical decision about permanent pacemaker implantation is made.

non-reversible cause: asymptomatic without indications for pacing

1st line – reassurance

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1st line –

reassurance

Pacing is indicated when any of the following is present: high-grade atrioventricular (AV) block, Mobitz type II second-degree AV block, third-degree AV block, or evidence of infranodal block that is not caused by a physiological mechanism or reversible cause, regardless of symptoms. In addition, patients who underwent catheter ablation of the AV junction; or those who develop persistent AV block after surgical or transcutaneous implantation of aortic or mitral valve prostheses, or after surgical myectomy or alcohol septal ablation for hypertrophic cardiomyopathy; and those with certain specific neuromuscular diseases (e.g., myotonic dystrophy type 1 or Kearns-Sayre syndrome) and infiltrative cardiomyopathies (sarcoidosis, amyloidosis) with any of the above AV conduction abnormalities, should undergo permanent pacemaker implantation.[11]

If these indications are absent and the patient is asymptomatic, no specific treatment is required and the patient can be reassured.

non-reversible cause: symptomatic or indications for pacing

1st line – permanent pacing

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1st line –

permanent pacing

Additionally, patients with persistent atrial fibrillation and symptomatic bradycardia, and patients with symptomatic bradycardia who need to be on rate-lowering medications for long-term guideline-directed management of another cardiac condition (e.g., coronary artery disease, systolic congestive heart failure), should be referred for permanent pacemaker implantation.[11]

As a general rule, all symptomatic patients with AV block require permanent pacing regardless of the specific type or anatomical level of AV block. Permanent pacing is the only available therapeutic modality for persistent acquired atrioventricular (AV) block as a result of non-reversible causes.

Ventricle-based (VVI), dual chamber (DDD), and atrial synchronous-ventricular inhibited (VDD) pacing modes are useful in correcting bradycardia caused by AV block. Although the optimal pacing mode remains controversial, modes that preserve AV synchrony (VDD or DDD) are preferred.

Consider the use of a biventricular pacemaker or a conduction system pacemaker in patients who need pacing and have a left ventricular ejection fraction of 36% to 50%, and a high (>40%) expected burden of ventricular pacing.

Symptomatic bradycardia in patients in whom the level of AV block is at the level of the AV node should be considered for a His-bundle lead-based dual chamber pacemaker.

Accumulating evidence suggests that right ventricular pacing in patients with systolic left ventricular dysfunction may be associated with increased risk of atrial fibrillation, worsening heart failure, and mortality secondary to left ventricular desynchronisation. Therefore, pacing of the ventricle should be avoided in patients with preserved AV conduction.[58][61]

hemodynamically stable: congenital atrioventricular block

asymptomatic without indications for pacing

1st line – reassurance

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1st line –

reassurance

Indications for pacing include wide QRS escape rhythm, complex ventricular arrhythmia, or impaired systolic left ventricular function. Although not agreed universally, pacing should also be considered strongly in asymptomatic patients with ventricular escape rhythm of <50 bpm or prolonged ventricular pauses. If these indications are absent, no specific treatment is required and the patient can be reassured.

Some data suggest that early institution of pacing in asymptomatic patients may improve survival. However, whether or not all asymptomatic patients with congenital atrioventricular block require permanent pacemaker implantation remains controversial.

symptomatic or indications for pacing

1st line – permanent pacing

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1st line –

permanent pacing

There is a general consensus that permanent pacing is indicated for all symptomatic patients or for asymptomatic patients with any of the following: wide QRS escape rhythm, complex ventricular arrhythmia, a mean daytime heart rate of <50 bpm, or impaired systolic left ventricular function.

In addition, patients with adult congenital heart disease (ACHD) who have significant atrioventricular (AV) conduction abnormalities (high-grade AV block, Mobitz II second-degree AV block, or third-degree AV block that is not expected to resolve) should undergo permanent pacemaker implantation, and pacemaker algorithms that reduce the risk of atrial arrhythmias should be incorporated in these devices.[11]

Although not agreed universally, pacing should be considered strongly in asymptomatic patients with ventricular escape rhythm of <50 bpm or prolonged ventricular pauses.

Pacing modes that preserve AV synchrony (atrial synchronous-ventricular inhibited [VDD] or dual chamber [DDD]) are usually used.

haemodynamically stable: vagally mediated bradycardia

carotid hypersensitivity syndrome

1st line – permanent pacing

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1st line –

permanent pacing

Pacing may be indicated for patients with recurrent symptoms who demonstrate a hyperactive response to carotid sinus massage (defined as ventricular asystolic pause of >3 seconds), are thought to have symptoms owing to hypersensitive carotid sinus, and have no other explainable cause for syncope.

neurocardiogenic or vasovagal syncope

1st line – lifestyle modifications

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1st line –

lifestyle modifications

Initial approach is usually based on education and lifestyle modification, regardless of the intrinsic autonomic mechanism underlying syncopal events.

The main aspects of this approach include: identification and avoidance of precipitating factors; measures to be taken during impending events, such as lying down, elevation of legs, and tensing manoeuvres; adequate fluid and salt intake.

2nd line – pharmacotherapy

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2nd line –

pharmacotherapy

The role of medicine is limited.

Multiple drugs with different mechanisms have been used; however, none of them have improved outcome in prospective controlled trials.[64][65]

Medical therapy is usually considered in patients who do not respond to lifestyle modifications. The choice of the drug is made on an individual basis.

The most commonly used drugs are fludrocortisone, midodrine, and selective serotonin-reuptake inhibitors (SSRIs).

European guidelines state that fludrocortisone should be considered in young patients with orthostatic vasovagal syncope with low-to-normal arterial blood pressure, while midodrine should be considered in patients with vasovagal syncope and orthostatic symptoms.[67]

Primary options

fludrocortisone: 0.1 to 0.2 mg orally once daily

midodrine: 2.5 to 10 mg orally three times daily

fluoxetine: 20 mg orally once daily

3rd line – permanent pacing

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3rd line –

permanent pacing

Pacing is reserved for patients with recurrent severe episodes of syncope refractory to medical therapy who have significant bradycardia documented during clinical events.

Heart-rate response observed during tilt-table testing may not correlate with that during clinical events and should be used with caution for the selection of patients who may or may not benefit from pacing.

When pacing is considered for neurocardiogenic syncope, the dual chamber (DDD) pacing mode is considered to be the preferred pacing mode. The value of programmable pacemaker features such as rate-drop response (during which the rate increases abruptly if a gradual slowing is seen), or closed loop stimulation (during which pacing rate increases if there is evidence of changes in local impedance that may reflect changes in right ventricular contractility by a proprietary algorithm), may be beneficial.[64][65]

haemodynamically stable: bradycardia associated with neurological disorders

1st line – consider permanent pacing

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1st line –

consider permanent pacing

Bradycardia can be acute (e.g., Cushing's reflex) or chronic. In many situations, the bradycardia may be transient. First, identify and eliminate reversible causes. Watchful waiting for spontaneous resolutions is reasonable. Permanent pacing may be needed in a small proportion of patients.

In patients with epilepsy associated with severe symptomatic bradycardia (ictal bradycardia) that are not controlled with anti-epileptic medications, permanent pacing is a reasonable treatment option for reducing the severity of symptoms.[11]

Patients diagnosed with myotonic dystrophy type 1 or Kearns-Sayre syndrome, who have evidence of second-degree atrioventricular (AV) block, third-degree AV block, or an abnormal electrophysiology study (H-V interval of ≥70 ms), should be referred for pacemaker (or implantable cardioverter defibrillator [ICD] if there is concomitant systolic dysfunction) implantation regardless of symptoms, if meaningful survival of more than 1 year is expected.[11]

Patients with traumatic spinal cord injury (above the sixth thoracic vertebra level) can have episodes of profound bradycardia in response to painful or noxious stimuli. These episodes usually resolve over time and with elimination of noxious stimuli, and conservative measures and watchful waiting for resolution of symptomatic bradycardia is preferable.[11]

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Bradycardia

Treatment algorithm

haemodynamically unstable

pharmacotherapy

Primary options

Secondary options

temporary pacing

haemodynamically stable: sinus node dysfunction

treatment of underlying cause

theophylline

Primary options

treatment of underlying cause + temporary pacing

reassurance

permanent pacing

haemodynamically stable: acquired atrioventricular block

treatment of underlying cause

treatment of underlying cause + temporary pacing

reassurance

permanent pacing

hemodynamically stable: congenital atrioventricular block

reassurance

permanent pacing

haemodynamically stable: vagally mediated bradycardia

permanent pacing

lifestyle modifications

pharmacotherapy

Primary options

permanent pacing

haemodynamically stable: bradycardia associated with neurological disorders

consider permanent pacing