What is the management for a patient with sinus bradycardia, second-degree AV block, multifocal PVCs, and supraventricular tachycardia?

Management of Complex Arrhythmia Case with Sinus Bradycardia, AV Block, and Frequent Ventricular Ectopy

This patient requires permanent pacemaker implantation given the presence of both Mobitz II second-degree AV block and symptomatic pauses exceeding 2.2 seconds, followed by careful management of the high ventricular ectopic burden (>27,000 PVCs/day) which poses risk for tachycardia-induced cardiomyopathy. 1, 2

Primary Management Priority: Address Conduction System Disease

Pacemaker Indication (Class I)

• Permanent pacemaker implantation is mandatory for Mobitz II second-degree AV block, as this infranodal block carries high risk of progression to complete heart block and sudden cardiac arrest 1
• The 61 pauses with durations of 2.2-2.4 seconds further support pacemaker indication, particularly if symptomatic (the patient pressed symptom button 4 times during monitoring) 2
• Mobitz II block is almost always located below the AV node and has poor prognosis without pacing 1

Pre-Pacemaker Considerations

• Exclude reversible causes before pacemaker implantation: 3
  • Digitalis toxicity (check digoxin level if patient on digitalis)
  • Hypokalemia or other electrolyte abnormalities
  • Myocardial ischemia (obtain troponin, consider stress testing or coronary angiography)
  • Medications causing bradycardia (beta-blockers, calcium channel blockers, antiarrhythmics)
• If digitalis toxicity is present with junctional rhythm and AV block, withhold digitalis; use digitalis-binding agents only if ventricular arrhythmias or high-grade block present 3

Secondary Management: Ventricular Ectopy Burden

Assessment of PVC Burden

• 27,520 PVCs per day represents approximately 19% of total beats (assuming average HR 56 bpm over 24 hours), which is a very high burden 2
• The presence of V-pairs (15), V-triplets (2), and extensive bigeminy (2,005 events) indicates organized ventricular ectopy 2
• Obtain echocardiogram to assess for PVC-induced cardiomyopathy, as persistent high-burden PVCs are associated with left ventricular dysfunction 2

Management After Pacemaker Implantation

Once pacemaker is in place and bradycardia is addressed, initiate beta-blocker therapy for PVC suppression: 3, 4

• Beta-blockers are first-line for symptomatic PVCs and junctional rhythms 3
• Metoprolol is preferred given its beta-1 selectivity and established safety profile 4
• Start with low dose (e.g., metoprolol 25 mg twice daily) and titrate based on symptom control and PVC burden reduction 4

Alternative or adjunctive therapy if beta-blockers insufficient: 3

• Nondihydropyridine calcium channel blockers (diltiazem or verapamil) may be added for persistent junctional tachycardia 3
• Avoid Class IC antiarrhythmics (flecainide, propafenone) until structural heart disease is excluded, as these carry risk of proarrhythmia and heart failure exacerbation 5
• Flecainide is contraindicated if any structural heart disease, prior MI, or heart failure present 5

Management of Supraventricular Arrhythmias

SVT Episodes

• The 2 episodes of SVT (4-25 beats, rates up to 106 bpm) are brief and relatively slow 3
• These likely represent paroxysmal supraventricular tachycardia or atrial tachycardia, which may be related to the underlying sinus node dysfunction 3
• Beta-blockers initiated for PVC management will also provide rate control for SVT episodes 3

Supraventricular Ectopy

• The 70 supraventricular ectopic beats represent minimal burden and typically require no specific therapy 6
• Reassure patient that isolated SVEs are benign findings commonly seen on extended monitoring 6

Critical Pitfalls to Avoid

Do Not Use Beta-Blockers or Calcium Channel Blockers Before Pacemaker

• Never initiate AV nodal blocking agents (beta-blockers, calcium channel blockers) in a patient with Mobitz II block without pacemaker protection, as this will worsen AV conduction and may precipitate complete heart block 4
• The junctional escape rhythm may be suppressed by these medications, eliminating the patient's backup rhythm 3

Avoid Flecainide Without Careful Screening

• Flecainide can cause new or worsened AV block (4% develop new bundle branch block, 0.5% develop second-degree block, 0.4% develop third-degree block) 5
• Flecainide should not be used if any degree of heart failure, structural heart disease, or conduction abnormalities present 5
• Given this patient's existing Mobitz I and II block, flecainide is relatively contraindicated even after pacemaker placement 5

Monitor for Bradycardia-Tachycardia Syndrome

• The combination of sinus bradycardia, junctional rhythm, and episodes of SVT suggests possible sick sinus syndrome with bradycardia-tachycardia variant 7, 2
• Pacemaker implantation is the definitive treatment for this syndrome, allowing safe use of antiarrhythmic medications for tachycardia control 7, 2

Post-Pacemaker Follow-Up Algorithm

1. Verify pacemaker function at 1 week: Check pacing thresholds, as antiarrhythmic drugs may increase thresholds 5
2. Repeat echocardiogram in 3-6 months to assess for improvement or resolution of any PVC-induced cardiomyopathy after treatment 2
3. Repeat Holter monitoring after beta-blocker titration to document PVC burden reduction (target <10% of total beats) 2
4. Consider EP study and catheter ablation if PVC burden remains >10,000/day despite medical therapy and LV dysfunction persists 3