New ACC/AHA/HRS Guidance on Bradycardia, Conduction Disorders

Megan Brooks

November 06, 2018

The American College of Cardiology (ACC), the American Heart Association (AHA), and the Heart Rhythm Society (HRS) have released a clinical practice guideline for the evaluation and treatment of patients with bradycardia and cardiac conduction disorders.

"Recommendations for the initial evaluation of patients with overt or suspected bradycardia or conduction disorders have not previously been made and recommendations for the acute management of bradycardia supplement and provide more detail for the AHA ACLS [Advanced Cardiac Life Support] Adult Bradycardia Algorithm," Fred N. Kusumoto, MD, who chaired the guideline writing committee, told | Medscape Cardiology.

The guideline emphasizes that treatment decisions should be based not only on the best available evidence, but also on the patient's goals of care and preferences.

"Patient symptoms and goals are central to any decision on pacemaker therapy. The patient must have an active role on whether to initiate or withdraw pacemaker therapy, and if the decision is made to initiate pacemaker therapy, then careful consideration for optimal implementation and device type is required," said Kusumoto.

The 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay, along with the systematic review of evidence, was published online November 6 in the Journal of the American College of Cardiology, Circulation, and HeartRhythm.

The guideline defines bradycardia as a heart rate below 50 beats/min (compared with a normal heart rate of 50 to 100 beats/min) and notes that bradycardia is generally classified into three categories: sinus node dysfunction, atrioventricular (AV) block, and conduction disorders.

The guideline outlines the clinical presentation and optimal clinical evaluation of patients with suspected bradycardia or conduction diseases.

Based on their review of available data, the committee developed recommendations on the selection and timing of diagnostic testing tools (including monitoring devices and electrophysiologic testing) and on available treatment options, including lifestyle interventions, pharmacotherapy, and external and implanted devices, particularly pacing devices.

The guideline also addresses special considerations for different populations on the basis of age, comorbidities, and other relevant factors.

Top 10 Take-Home Messages for the Management of Bradycardia and Cardiac Conduction Delay
1. Sinus node dysfunction is most often related to age-dependent progressive fibrosis of the sinus nodal tissue and surrounding atrial myocardium, leading to abnormalities of sinus node and atrial impulse formation and propagation, which will therefore result in various bradycardic or pause-related syndromes.
2. Sleep disorders of breathing and nocturnal bradycardias are relatively common, and treatment of sleep apnea not only reduces the frequency of these arrhythmias but also might offer cardiovascular benefits. The presence of nocturnal bradycardias should prompt consideration of screening for sleep apnea, beginning with solicitation of suspicious symptoms. However, nocturnal bradycardia is not in itself an indication for permanent pacing.
3. The presence of left bundle branch block on electrocardiogram (ECG) markedly increases the likelihood of underlying structural heart disease and of diagnosing left ventricular systolic dysfunction. ECG is usually the most appropriate initial screening test for structural heart disease, including left ventricular systolic dysfunction.
4. In sinus node dysfunction, there is no established minimum heart rate or pause duration for which permanent pacing is recommended. Establishing temporal correlation between symptoms and bradycardia is important when determining whether permanent pacing is needed.
5. In patients with acquired second-degree Mobitz type II AV block, high-grade AV block, or third-degree AV block not caused by reversible or physiologic causes, permanent pacing is recommended regardless of symptoms. For all other types of AV block, in the absence of conditions associated with progressive AV conduction abnormalities, permanent pacing should generally be considered only in the presence of symptoms that correlate with AV block.
6. In patients with a left ventricular ejection fraction between 36% and 50% and AV block, who have an indication for permanent pacing and are expected to require ventricular pacing more than 40% of the time, techniques that provide more physiologic ventricular activation (e.g., cardiac resynchronization therapy, His bundle pacing) are preferred to right ventricular pacing to prevent heart failure.
7. Because conduction system abnormalities are common after transcatheter aortic valve replacement, recommendations on postprocedure surveillance and pacemaker implantation are made in this guideline.
8. In patients with bradycardia who have indications for pacemaker implantation, shared decision-making and patient-centered care are endorsed and emphasized in this guideline. Treatment decisions are made on the basis of the best available evidence and on the patient's goals of care and preferences.
9. Using the principles of shared decision-making and informed consent or refusal, patients with decision-making capacity or their legally defined surrogates have the right to refuse or request withdrawal of pacemaker therapy, even pacemaker-dependent patients, which should be considered palliative, end-of-life care, and not physician-assisted death. However, any decision is complex, should involve all stakeholders, and will always be patient-specific.
10. Identifying patient populations that will benefit the most from emerging pacing technologies (e.g., His bundle pacing, transcatheter leadless pacing systems) require further investigation as these modalities are incorporated into clinical practice.


Disclosures for the guideline writing committee are listed in the paper.

J Am Coll Cardiol. Published online November 6, 2018. Executive summary, Systematic review, Guideline

Circulation. Published online November 6, 2018. Executive summary, Systematic review, Guideline

HeartRhythm. Published online November 6, 2018. Executive summary, Systematic review, Guideline


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