What is the treatment for first-degree atrioventricular (AV) block in an elderly female with syncope?

From the Guidelines

First-degree heart block in an elderly female with collapse typically doesn't require specific treatment as it's generally benign, and the initial approach should focus on identifying and addressing the cause of the collapse, which may be unrelated to the heart block. The patient's collapse could be due to various causes such as orthostatic hypotension, dehydration, or vasovagal syncope, which would require appropriate management. A thorough evaluation including vital signs, ECG, electrolyte panel, and medication review is essential to determine the underlying cause of the collapse. If the patient is on medications that slow cardiac conduction (such as beta-blockers, calcium channel blockers, or digoxin), these may need to be reduced or discontinued under medical supervision 1.

According to the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay, permanent pacing can alleviate symptoms in adults with atrioventricular block, but there is no clear evidence to support its use in asymptomatic patients with first-degree heart block 1. However, in rare cases where first-degree heart block is symptomatic and contributing to the collapse, a pacemaker might be considered. The patient should be educated about the generally benign nature of first-degree heart block while ensuring appropriate follow-up to monitor for any progression.

Some key points to consider in the management of this patient include:

• Identifying and addressing the underlying cause of the collapse
• Reducing or discontinuing medications that slow cardiac conduction if necessary
• Monitoring for progression of the heart block or development of symptoms
• Considering pacemaker implantation in rare cases where first-degree heart block is symptomatic and contributing to the collapse
• Educating the patient about the generally benign nature of first-degree heart block and the importance of follow-up care.

From the Research

Treatment for First-Degree Heart Block

• The treatment for first-degree heart block in an elderly female with collapse is not directly addressed in the provided studies, but some insights can be gained from the available information.
• According to 2, marked first-degree AV block (PR> or =0.30 s) can produce a clinical condition similar to that of the pacemaker syndrome, and clinical evaluation often requires a treadmill stress test.
• Uncontrolled studies have shown that many symptomatic patients with normal left ventricular (LV) function improve with conventional dual chamber pacing (Class IIa indication) 2.
• However, marked first-degree AV block with LV systolic dysfunction and heart failure is still a Class IIb indication, and it may be prudent to consider a biventricular DDD device in this situation 2.
• Patients with first-degree AV block have a poorer outcome with cardiac resynchronization therapy (CRT) than patients with a normal PR interval, which may involve several mechanisms, including the long PR interval being a marker of more advanced heart disease 2.

Considerations for Pacemaker Management

• Patients with suboptimally programmed pacemakers may develop functional atrial undersensing because the P wave tends to migrate easily into the postventricular atrial refractory period (PVARP) 2.
• A relatively short PVARP can often be used at rest with little risk of endless loop tachycardia, but the usefulness of a short PVARP may be negated by special PVARP functions in some pulse generators 2.
• First-degree AV block during cardiac resynchronization therapy (CRT) predisposes to loss of ventricular resynchronization during biventricular pacing, especially in association with a relatively fast atrial rate and a relatively slow programmed upper rate 2.

Outcomes and Therapeutic Implications

• The prevalence of first-degree atrioventricular block in the general population is approximately 4%, and it is associated with an increased risk of atrial fibrillation 3.
• Cardiac pacing for any indication in patients with first-degree heart block is associated with worse outcomes compared with patients with normal atrioventricular conduction 3.
• Data from cardiac resynchronization therapy studies have shown that first-degree atrioventricular block is associated with an increased risk of mortality and heart failure hospitalization 3.