What are the next steps for a patient with diabetes, obesity, and a first-degree atrioventricular (AV) block, who is experiencing dizziness and is currently taking amlodipine (10mg) and Mounjaro (tirzepatide)?

Management of Dizziness in a Patient with First-Degree AV Block on Amlodipine and Mounjaro

Discontinue or reduce amlodipine immediately, as it is the most likely culprit for dizziness in this patient with first-degree AV block, and first-degree AV block itself requires no treatment but serves as a precaution against further AV nodal blockade. 1

Immediate Assessment Priorities

Evaluate the dizziness characteristics and rule out life-threatening causes:

• Obtain orthostatic vital signs to assess for orthostatic hypotension, which is a common adverse effect of amlodipine, particularly at the 10 mg dose 2
• Assess timing and triggers of dizziness episodes—whether positional (suggesting benign paroxysmal positional vertigo), continuous (suggesting cardiovascular or metabolic cause), or episodic with specific triggers 2
• Check for symptoms of hypoperfusion including altered mental status, acute heart failure, or diaphoresis that would require emergency department transfer 3
• Perform Dix-Hallpike maneuver if dizziness is triggered by position changes to evaluate for benign paroxysmal positional vertigo 2

Address the First-Degree AV Block

First-degree AV block (PR interval >0.20 seconds) is generally benign and asymptomatic, requiring no specific treatment in isolation. 1, 3

• Do not attribute dizziness to first-degree AV block unless the PR interval is markedly prolonged (>300 milliseconds), which can cause pacemaker syndrome-like symptoms with hemodynamic compromise 1, 3
• First-degree AV block is a contraindication to adding further AV nodal blocking agents including beta-blockers, non-dihydropyridine calcium channel blockers (diltiazem, verapamil), or digoxin 1
• Amlodipine, as a dihydropyridine calcium channel blocker, does not significantly affect AV nodal conduction but can cause hypotension and dizziness through peripheral vasodilation 1

Medication Management Strategy

Reduce or discontinue amlodipine as the primary intervention:

• Amlodipine 10 mg is a high dose and commonly causes dizziness, lightheadedness, and orthostatic hypotension through excessive vasodilation 1
• Consider reducing to 5 mg or discontinuing entirely depending on blood pressure control needs and whether alternative antihypertensive agents are required
• If blood pressure control is needed, avoid AV nodal blocking agents (beta-blockers, diltiazem, verapamil) given the first-degree AV block 1
• Alternative antihypertensives could include ACE inhibitors, ARBs, or thiazide diuretics, which do not affect AV conduction 1

Evaluate Mounjaro (Tirzepatide) Contribution

Assess for tirzepatide-related complications that could contribute to dizziness:

• Check comprehensive metabolic panel including potassium, magnesium, and calcium, as severe gastrointestinal side effects from tirzepatide (particularly at higher doses) can cause profound electrolyte disturbances leading to arrhythmias and dizziness 4
• Tirzepatide commonly causes gastrointestinal side effects including nausea, vomiting, and diarrhea, which can lead to dehydration and orthostatic hypotension 5, 4
• Volume depletion from GI side effects combined with amlodipine's vasodilatory effects creates a particularly high risk for symptomatic hypotension 5, 4
• If severe GI symptoms are present, consider dose reduction or temporary discontinuation of tirzepatide, as electrolyte disturbances from GI losses have been associated with life-threatening arrhythmias 4

Metabolic and Cardiovascular Workup

Obtain targeted laboratory and diagnostic studies:

• 12-lead ECG to measure the exact PR interval, assess for higher-degree AV block, and evaluate for other conduction abnormalities or ischemic changes 3
• Basic metabolic panel to assess electrolytes (particularly potassium, magnesium, calcium) that could contribute to both dizziness and conduction abnormalities 4
• Hemoglobin A1c and fasting glucose to assess diabetes control, as hypoglycemia can cause dizziness 5
• Consider Holter monitor if symptoms suggest intermittent arrhythmia or if there is concern for progression to higher-degree AV block 1

Critical Pitfalls to Avoid

Common errors in managing this clinical scenario:

• Do not add beta-blockers or non-dihydropyridine calcium channel blockers for blood pressure control, as these are contraindicated with first-degree AV block and could precipitate higher-degree block 1
• Do not dismiss dizziness as solely related to the AV block when amlodipine is a far more likely culprit at this dose 3
• Do not overlook electrolyte monitoring in patients on tirzepatide with GI symptoms, as severe disturbances can be life-threatening 4
• Do not assume first-degree AV block requires pacemaker evaluation unless the PR interval exceeds 300 milliseconds with hemodynamic symptoms or there is progression to higher-degree block 1

Monitoring and Follow-Up

Establish a structured follow-up plan:

• Reassess symptoms within 1-2 weeks after amlodipine adjustment to determine if dizziness resolves 2
• Repeat ECG in 3-6 months to monitor for progression of AV block, particularly if any AV nodal blocking agents become necessary for other indications 1
• Monitor electrolytes regularly if continuing tirzepatide, especially if GI side effects persist 4
• Consider referral to cardiology only if dizziness persists despite medication adjustment, if higher-degree AV block develops, or if the PR interval is markedly prolonged (>300 ms) with symptoms 1, 3