What is the treatment for complete heart block?

Treatment of Complete Heart Block

Permanent pacemaker implantation is the definitive treatment for complete heart block, with immediate pacing required for symptomatic patients and strong consideration for permanent pacing even in asymptomatic patients given the established survival benefit. 1

Immediate Management

Symptomatic Patients

• Temporary pacing is indicated immediately for symptomatic bradycardia, including syncope, near-syncope, dizziness, confusion from cerebral hypoperfusion, fatigue, reduced exercise capacity, or heart failure. 1
• Atropine can be used as a temporizing measure while preparing for pacing, as it may accelerate the idioventricular rate in some patients with complete heart block, though its effect is inconsistent. 2
• Continuous cardiac monitoring is mandatory during the acute phase, as complete heart block represents a potentially life-threatening condition requiring urgent evaluation. 3

Asymptomatic Patients

• Even asymptomatic patients with complete heart block should be referred immediately to the emergency department for continuous monitoring and evaluation for permanent pacemaker placement. 3
• Historical data demonstrates mortality rates of 32% at one year and 63% at five years without pacing in untreated complete heart block, compared to significantly improved survival with permanent pacing. 3
• Non-randomized studies strongly demonstrate that permanent pacing improves survival in third-degree AV block, particularly when implemented before symptoms develop. 1, 3

Permanent Pacemaker Indications (Class I)

Symptomatic Complete Heart Block

• Permanent pacemaker implantation is mandatory (Class I indication) for third-degree AV block with any of the following: 1
  • Symptomatic bradycardia of any type
  • Documented asystole ≥3.0 seconds in awake patients
  • Escape rate <40 bpm in awake patients in sinus rhythm
  • Ventricular arrhythmias presumed due to the AV block

Medication-Related Block

• Permanent pacing is indicated when required medications (beta-blockers, calcium channel blockers, antiarrhythmics) cause symptomatic bradycardia that cannot be managed by alternative therapies. 1

Post-Procedural Complete Heart Block

• Immediate permanent pacemaker implantation is indicated for complete heart block after catheter ablation of the AV junction (Class I indication). 1
• Advanced second- or third-degree AV block persisting for at least 7 days after cardiac surgery and not expected to resolve is a Class I indication for permanent pacing. 4
• Patients with permanent postsurgical AV block who do not receive permanent pacemakers have a very poor prognosis. 4

Neuromuscular Disease-Associated Block

• Permanent pacing is indicated for third-degree AV block associated with myotonic muscular dystrophy, Kearns-Sayre syndrome, Erb dystrophy, or peroneal muscular atrophy, with or without symptoms, due to unpredictable progression. 1

Special Populations

Congenital Complete Heart Block

• Pacemaker implantation is a Class I indication for symptomatic patients or infants with heart rate <55 bpm (<70 bpm when associated with structural heart disease). 4, 1
• In asymptomatic children or adolescents with congenital complete AV block, multiple criteria must be considered: average heart rate, pauses in intrinsic rate, associated structural heart disease, QT interval, and exercise tolerance. 4
• Long-term ventricular function monitoring is required after pacemaker implantation due to risk of ventricular dysfunction from pacemaker-induced dyssynchrony, which may occur years or decades after implantation. 4, 1

Acute Myocarditis

• Temporary pacemaker insertion is indicated for symptomatic bradycardia and/or heart block during the acute phase of myocarditis (Class I indication). 4
• ICD implantation is not indicated during the acute phase of myocarditis but can be beneficial for life-threatening ventricular arrhythmias once the acute phase has resolved. 4

Critical Pitfalls to Avoid

Do Not Delay for Outpatient Workup

• The risk of sudden death or syncope with injury during the days-to-weeks wait for outpatient cardiology appointments is unacceptable in complete heart block. 3
• Immediate emergency department referral with continuous monitoring is mandatory, even in asymptomatic patients. 3

Do Not Confuse with Lesser Degrees of AV Block

• First-degree and Mobitz I (Wenckebach) second-degree AV block may be managed outpatient in asymptomatic patients, but complete heart block cannot. 3
• Complete heart block is pathologic at any age and should not be attributed to "normal aging" in elderly patients. 3

Exercise Testing Considerations

• In athletes, a simple exercise test can differentiate between complete heart block and benign AV dissociation, with normalization during exercise suggesting the latter. 3
• If the block persists with exercise or the patient is not an athlete, immediate emergency department referral is mandatory. 3

Long-Term Outcomes

• Young adults with complete heart block who receive permanent pacemakers demonstrate marked improvement in functional symptomatology, with most achieving functional class I status. 5
• Periodic evaluation of ventricular function is required after pacemaker implantation, as ventricular dysfunction may occur from myocardial autoimmune disease or pacemaker-associated dyssynchrony. 4
• The survival rate in untreated complete heart block is significantly lower than in paced patients, with observational studies demonstrating clear survival benefit from permanent pacing, particularly when syncope has occurred. 1, 6