In a hemodynamically stable patient with atrial fibrillation and rapid ventricular response of 103 bpm who also has a moderate right‑sided pleural effusion involving more than half of the lung, how should the ventricular rate be managed according to Canadian guidelines?

Management of Atrial Fibrillation with RVR at 103 bpm in the Presence of Moderate Pleural Effusion

Yes, you should manage the rate in this patient, but first address the pleural effusion as it is likely the primary driver of the rapid ventricular response, and rate control alone may be insufficient or potentially harmful if the underlying cause is not treated. 1, 2

Initial Assessment and Hemodynamic Stability

• Since the patient is hemodynamically stable at 103 bpm, urgent electrical cardioversion is not indicated 3, 1
• A heart rate of 103 bpm technically falls within the "lenient" rate control target of <110 bpm at rest, but this does not mean you should ignore it in the context of a significant pleural effusion 3
• The moderate pleural effusion (>50% of lung) is a reversible precipitating factor that must be systematically evaluated and treated 1, 2

Address the Underlying Cause First

The pleural effusion is likely causing hypoxemia, increased sympathetic tone, and hemodynamic stress that is driving the rapid ventricular response. 1

• Pleural effusions causing significant lung compression can precipitate or worsen atrial fibrillation through multiple mechanisms including hypoxemia, increased work of breathing, and altered intrathoracic pressures 1
• Treating the effusion (thoracentesis if indicated) may improve or resolve the rapid ventricular response without aggressive pharmacologic rate control 1
• Obtain chest imaging, assess oxygenation status, and consider diagnostic/therapeutic thoracentesis based on the clinical picture 1

Rate Control Strategy While Addressing the Effusion

Even though 103 bpm is not severely elevated, rate control should still be initiated given the presence of symptoms or the need to prevent tachycardia-mediated cardiomyopathy. 3

First-Line Agent Selection:

• Beta-blockers (metoprolol) are the preferred first-line agent for rate control in this hemodynamically stable patient 3, 1, 4
• Metoprolol 2.5-5 mg IV bolus over 2 minutes can be given acutely if immediate rate control is needed, followed by oral maintenance dosing of 25-100 mg twice daily 4
• However, use beta-blockers with extreme caution in the setting of a large pleural effusion, as they may worsen respiratory symptoms or mask compensatory tachycardia from hypoxemia 3

Alternative if Beta-Blockers are Contraindicated:

• Diltiazem 0.25 mg/kg IV over 2 minutes, followed by 5-15 mg/hour infusion, is equally effective and may be preferred if there are concerns about bronchospasm or respiratory compromise 4, 5
• Diltiazem achieves rate control faster than metoprolol in some studies 5
• Avoid calcium channel blockers if there is any evidence of heart failure or reduced ejection fraction (LVEF ≤40%), as they can worsen hemodynamic compromise 3, 2

Target Heart Rate Goals

• The target resting heart rate should be 60-80 bpm for strict rate control 2, 4
• A lenient strategy targeting <110 bpm at rest may be reasonable if the patient remains asymptomatic and LV systolic function is preserved, but this should be reassessed after the pleural effusion is treated 3
• Rate control should be assessed during activity, not just at rest, with a target of 90-115 bpm during moderate exercise 3, 2

Critical Pitfalls to Avoid

• Do not aggressively rate control without addressing the pleural effusion, as the tachycardia may be a compensatory response to hypoxemia or increased work of breathing 1
• Avoid calcium channel blockers if the patient has decompensated heart failure or significant left ventricular dysfunction, as they may exacerbate hemodynamic compromise 3, 2
• Never use digoxin as monotherapy in an active patient, as it only controls rate at rest and is ineffective during exercise 1
• Monitor closely for hypotension and bradycardia when initiating rate control agents, especially in the setting of potential respiratory compromise 4

Anticoagulation Consideration

• Calculate the CHA₂DS₂-VASc score immediately to assess stroke risk 1
• If CHA₂DS₂-VASc score ≥2, initiate anticoagulation with a direct oral anticoagulant (apixaban, rivaroxaban, edoxaban, or dabigatran) 1

Algorithmic Approach

1. Confirm hemodynamic stability (no hypotension, ongoing ischemia, or pulmonary edema) 3, 1
2. Evaluate and treat the pleural effusion as the primary reversible cause 1
3. Initiate rate control with metoprolol or diltiazem if the heart rate remains >80 bpm at rest after addressing the effusion 3, 2, 4
4. Reassess rate control after thoracentesis (if performed), as the ventricular response may improve significantly 1
5. Monitor for adverse effects including hypotension, bradycardia, and worsening respiratory status 4