Is a patient with fatigue and weakness, a 1st degree atrioventricular (AV) block, and a recent history of atrial fibrillation with rapid ventricular response (A-fib RVR) at risk for complications?

From the Guidelines

A patient with fatigue and weakness, a 1st degree atrioventricular (AV) block, and recent atrial fibrillation with rapid ventricular response (A-fib RVR) is at risk for complications and requires prompt medical evaluation, as indicated by the 2024 ESC guidelines for the management of atrial fibrillation 1. This combination of symptoms and cardiac abnormalities suggests potential progression to more severe conduction disorders or hemodynamic compromise. The 1st degree AV block, characterized by prolonged PR interval on ECG, may be benign alone but can progress to higher-degree blocks, especially in the context of recent A-fib RVR. Key considerations in management include:

• Continuous cardiac monitoring
• Assessment of electrolytes (particularly potassium and magnesium)
• Evaluation of medication effects
• Consideration of underlying causes such as ischemia, inflammation, or infiltrative diseases
• Review of anticoagulation status given the history of atrial fibrillation to prevent thromboembolic complications, as recommended by the guidelines 1. The fatigue and weakness could indicate inadequate cardiac output due to the arrhythmia or could be side effects of rate-controlling medications like beta-blockers (metoprolol, carvedilol), calcium channel blockers (diltiazem, verapamil), or digoxin. If the patient is on AV nodal blocking agents, dosage adjustment may be necessary, as these medications can worsen conduction delays. Given the recent history of A-fib RVR, it is crucial to follow the guidelines for management of atrial fibrillation, which emphasize the importance of rate control, rhythm control, and anticoagulation to prevent complications 1. The most recent guidelines should be prioritized in clinical decision-making, as they reflect the latest evidence and recommendations for patient care 1.

From the FDA Drug Label

Bradycardia, including sinus pause, heart block, and cardiac arrest have occurred with the use of metoprolol. Patients with first-degree atrioventricular block, sinus node dysfunction, or conduction disorders may be at increased risk. The patient with fatigue, weakness, a 1st degree atrioventricular (AV) block, and a recent history of atrial fibrillation with rapid ventricular response (A-fib RVR) may be at increased risk for complications such as bradycardia, including sinus pause, heart block, and cardiac arrest, particularly if they are taking medications like metoprolol 2. Close monitoring of heart rate and rhythm is recommended.

From the Research

Patient Condition

The patient presents with fatigue, weakness, a 1st degree atrioventricular (AV) block, and a recent history of atrial fibrillation with rapid ventricular response (A-fib RVR).

Risks and Complications

• Atrial fibrillation (AF) may lead to stroke, heart failure, and death 3.
• A-fib RVR can cause complications, including hypoperfusion and cardiac ischemia 3.
• First-degree AV block is generally considered benign, but extreme forms can cause symptoms due to inadequate timing of atrial and ventricular contractions 4.
• Patients with first-degree AV block have a poorer outcome with cardiac resynchronization therapy (CRT) than patients with a normal PR interval 5.

Management and Treatment

• Emergency physicians play a key role in the diagnosis and management of A-fib RVR 3.
• Differentiating primary and secondary A-fib RVR and evaluating hemodynamic stability are vital components of ED assessment and management 3.
• Rate or rhythm control should be pursued in hemodynamically stable patients 3.
• Anticoagulation is an important component of management, and several tools are available to assist with this decision 3.
• Permanent pacemaker implantation is reasonable for first-degree AV block with symptoms similar to those of pacemaker syndrome or with hemodynamic compromise 4.

Outcomes

• Patients with primary A-fib have lower adverse outcomes and some could potentially be treated as outpatients 6.
• Patients with secondary A-fib have higher rates of cardiovascular risk factors, longer length of stay, and higher ED reattendance and readmission rates 6.
• Mortality is higher in patients with secondary A-fib compared to primary A-fib 6.