What is the next best step for a 60-year-old male on bisoprolol (beta-blocker) with a Zio patch report showing normal sinus rhythm (NSR) with first-degree block, Wenckebach block, ventricular tachycardia (V.tach) and supraventricular tachycardia (SVT)?

Management of Complex Arrhythmias in a 60-Year-Old Male on Bisoprolol

The patient requires immediate referral for pacemaker implantation due to the presence of Wenckebach block with concurrent ventricular tachycardia and SVT episodes, which indicates significant conduction system disease requiring definitive intervention beyond medication adjustment.

Assessment of Findings

The Zio patch report reveals multiple concerning arrhythmias:

• Normal sinus rhythm with first-degree AV block
• Wenckebach (Mobitz Type I) AV block
• Ventricular tachycardia (runs of 7 beats, max rate 130 bpm)
• Supraventricular tachycardia (14.2 seconds, max rate 156 bpm)

This combination represents a complex arrhythmic profile that requires urgent attention.

Management Algorithm

Step 1: Evaluate Hemodynamic Status

• If patient is hemodynamically unstable (hypotension, altered mental status, chest pain, or heart failure symptoms): immediate hospitalization
• If hemodynamically stable: proceed with urgent outpatient evaluation

Step 2: Risk Stratification

1. High-risk features present:

   • Coexistence of Wenckebach block with ventricular tachycardia
   • Multiple arrhythmia types suggesting conduction system disease
   • Risk of progression to higher-degree AV block

2. Medication considerations:

   • Current beta-blocker (bisoprolol) may be exacerbating the AV block
   • However, discontinuation could worsen the ventricular tachycardia and SVT

Step 3: Definitive Management

Pacemaker implantation is indicated based on:

• Presence of symptomatic Wenckebach block 1
• Concurrent ventricular arrhythmias suggesting infranodal disease 2
• Risk of progression to complete heart block 1, 2

Temporary management while awaiting pacemaker:

• Consider hospitalization for monitoring if symptomatic
• Maintain bisoprolol for ventricular rate control of SVT and VT episodes
• Have atropine available for symptomatic bradycardia 1

Rationale for Recommendation

1. Wenckebach block significance:

   • While isolated Wenckebach block can be benign, its presence with ventricular arrhythmias suggests more extensive conduction system disease 1
   • The AHA/ACC guidelines note that Wenckebach with other conduction abnormalities may require pacing 1

2. Beta-blocker considerations:

   • Bisoprolol is effective for both supraventricular and ventricular arrhythmias 3
   • However, it may worsen AV block 4
   • Complete discontinuation could worsen tachyarrhythmias

3. Ventricular tachycardia management:

   • Runs of VT require treatment, especially in the setting of conduction disease
   • The combination of VT and conduction system disease suggests underlying structural heart disease

Important Caveats

• Location of block matters: While most Wenckebach blocks occur at the AV node level and are benign, some cases represent infranodal disease, which carries worse prognosis and higher risk of progression to complete heart block 2

• Beta-blocker paradox: While bisoprolol may worsen bradycardia and AV block, its discontinuation could exacerbate tachyarrhythmias. This clinical dilemma is best resolved with definitive pacing therapy 4

• Diagnostic considerations: An electrophysiology study may be warranted to determine the exact location of the block (nodal vs. infranodal) if there's uncertainty about the need for pacing 2

• Avoid temporary medication adjustments: Attempting to manage with medication adjustments alone is likely to be ineffective given the complexity of the arrhythmic profile

The presence of multiple arrhythmias including both bradyarrhythmias and tachyarrhythmias suggests significant cardiac conduction disease that requires definitive intervention rather than medication adjustment alone.