What is the management plan for a patient with a history of Non-ST-Elevation Myocardial Infarction (NSTEMI) and 3-vessel Coronary Artery Disease (CAD) who experiences episodes of bradycardia and Shortness of Breath (SOB)?

Management of Recurrent Bradycardia with Shortness of Breath in Post-NSTEMI Patient with 3-Vessel CAD

This patient requires continuous cardiac rhythm monitoring for >24 hours given the high-risk features of 3-vessel CAD and recurrent symptomatic bradycardia, with immediate assessment for ongoing ischemia, hemodynamic instability, and consideration of urgent coronary angiography if not already performed. 1

Immediate Assessment and Monitoring

Continuous rhythm monitoring is mandatory until the clinical picture is fully clarified, as this patient meets criteria for high-risk NSTEMI with major arrhythmias. 1

• Rhythm monitoring for >24 hours is specifically recommended for NSTEMI patients at increased risk for cardiac arrhythmias, which this patient clearly demonstrates with recurrent bradycardia episodes. 1

• Admit to a monitored unit immediately - the ESC guidelines explicitly state that all NSTEMI patients should be admitted to a monitored unit, and this patient has additional high-risk features. 1

• Obtain 12-lead ECG immediately with each symptomatic episode to assess for:

  • New ST-segment changes indicating ongoing ischemia 1
  • Degree and type of bradycardia (sinus vs. AV block) 1
  • Additional ECG leads (V3R, V4R, V7-V9) if ongoing ischemia is suspected 1

Critical Diagnostic Evaluation

Serial high-sensitivity cardiac troponin measurements are essential to determine if these episodes represent recurrent ischemia. 1

• Measure hs-cTn at 0h and 1h using the ESC 0h/1h algorithm if available, or alternatively at 0h and 2h. 1

• Echocardiography is recommended to evaluate:

  • Regional wall motion abnormalities suggesting ongoing ischemia 1
  • Left ventricular ejection fraction (LVEF <40% indicates higher risk) 1
  • Hemodynamic status 1

• Assess for hemodynamic instability - measure blood pressure during symptomatic episodes, as bradycardia with hypotension indicates very high-risk status requiring urgent intervention. 1

Determining the Cause of Bradycardia

Review all medications immediately - beta-blockers, calcium channel blockers, or other rate-limiting drugs may be contributing to symptomatic bradycardia in the setting of acute ischemia. 1

• Consider medication-induced bradycardia - if the patient is on beta-blockers or non-dihydropyridine calcium channel blockers, these may need dose reduction or temporary discontinuation. 1

• Evaluate for ischemia-mediated bradycardia - inferior wall ischemia commonly causes bradycardia and AV block, particularly in patients with 3-vessel CAD. 2

• Assess for high-degree AV block - the recurrent nature and association with symptoms suggests possible Mobitz II or third-degree block, which requires different management than sinus bradycardia. 1

Risk Stratification for Invasive Strategy

This patient has multiple high-risk features mandating urgent evaluation:

• 3-vessel CAD with recurrent symptoms indicates very high risk and typically requires early invasive strategy within 24 hours. 1

• Recurrent ischemia despite medical therapy (if symptomatic episodes represent ongoing ischemia) is a Class I indication for urgent coronary angiography. 1, 3

• Major arrhythmias (symptomatic bradycardia) classify this patient as high-risk requiring extended monitoring and consideration of urgent intervention. 1

• Hemodynamic instability (if present during episodes) mandates immediate invasive evaluation. 1, 3

Immediate Pharmacological Management

Anti-ischemic therapy optimization:

• Nitroglycerin (sublingual or IV) should be administered during symptomatic episodes unless contraindicated by hypotension (SBP <90 mmHg or >30 mmHg below baseline) or bradycardia <50 bpm. 1, 3

• Morphine sulfate IV may be considered for uncontrolled ischemic symptoms despite nitroglycerin, though it should be used cautiously as additional therapy to manage underlying ischemia. 1, 4

• Beta-blocker adjustment - if the patient is on beta-blockers and experiencing symptomatic bradycardia, these should be held or reduced. IV beta-blockers are contraindicated in patients with signs of heart failure, low-output state, or increased risk for cardiogenic shock. 1, 4

Atropine for symptomatic bradycardia:

• Atropine 0.5-0.6 mg IV is the drug of choice for symptomatic bradycardia with hypotension, particularly in inferior MI with AV block. 2

• Avoid initial doses >1.0 mg and cumulative doses >2.5 mg over 2.5 hours due to risk of ventricular tachycardia, ventricular fibrillation, or increased PVCs. 2

• Monitor carefully after atropine administration for adverse effects including sustained sinus tachycardia or worsening ventricular arrhythmias. 2

Antiplatelet and Anticoagulation Management

Ensure dual antiplatelet therapy is optimized:

• Aspirin 75-100 mg daily should be continued indefinitely. 1, 4, 5

• P2Y12 inhibitor (clopidogrel, ticagrelor, or prasugrel) should be continued for 12 months unless excessive bleeding risk. 1, 4, 5

• Parenteral anticoagulation should be continued if not already on therapeutic anticoagulation. 1, 4

Timing of Coronary Angiography

Urgent angiography (<2 hours) is indicated if:

• Hemodynamic instability persists 1, 3
• Ongoing ischemia despite intensive medical therapy 1, 3
• Life-threatening arrhythmias (though bradycardia alone may not meet this threshold) 1

Early angiography (within 24 hours) is indicated for:

• Recurrent symptoms despite medical therapy 1, 3, 4
• 3-vessel CAD with elevated troponin 1
• Major arrhythmias in the setting of NSTEMI 1

Temporary Pacing Consideration

Temporary pacing may be necessary if:

• High-degree AV block (Mobitz II or third-degree) is documented 1
• Symptomatic bradycardia persists despite atropine 2
• Hemodynamic compromise occurs with bradycardia 1

Common Pitfalls to Avoid

• Do not discharge or downgrade monitoring based on brief symptom resolution - the recurrent nature and 3-vessel CAD mandate extended observation. 1

• Do not delay angiography in patients with recurrent symptoms and 3-vessel CAD - this represents high-risk anatomy requiring urgent evaluation. 1, 3

• Do not continue rate-limiting medications (beta-blockers, non-dihydropyridine calcium channel blockers) at full doses if causing symptomatic bradycardia. 1

• Do not administer nitrates if systolic blood pressure <90 mmHg, severe bradycardia <50 bpm, or tachycardia >100 bpm without heart failure. 1

• Do not use immediate-release dihydropyridine calcium channel blockers without adequate beta-blockade, and avoid in the setting of bradycardia. 1, 4