When to check echo after starting Camzyos (Levokarnitin)?

Echocardiographic Monitoring Schedule for Camzyos (Mavacamten)

After starting Camzyos, obtain echocardiograms at 4 weeks, 8 weeks, and 12 weeks during the initiation phase, then every 12 weeks during maintenance therapy to monitor LVEF and Valsalva LVOT gradient. 1

Initiation Phase Monitoring (First 12 Weeks)

The FDA-approved dosing algorithm for Camzyos mandates specific echocardiographic surveillance intervals based on treatment phase 1:

• Week 4: First follow-up echocardiogram to assess LVEF and Valsalva LVOT gradient 1
• Week 8: Second follow-up echocardiogram for continued monitoring 1
• Week 12: Third echocardiogram to complete initiation phase assessment 1

Critical safety threshold: If LVEF drops below 50% at any visit, immediately interrupt Camzyos treatment regardless of the scheduled monitoring interval 1. Do not initiate or up-titrate Camzyos if LVEF is <55% 1.

Maintenance Phase Monitoring (After 12 Weeks)

Once the initiation phase is complete and the patient is on a stable dose:

• Every 12 weeks: Obtain echocardiogram to assess LVEF and Valsalva LVOT gradient 1
• Continue this quarterly monitoring schedule indefinitely while on therapy 1

Dose Adjustment Considerations

When titrating Camzyos dosage, the monitoring schedule resets 1:

• After any dose increase, obtain echocardiograms at 4 and 12 weeks following the change 1
• Important caveat: Delay dose increases during intercurrent illness (serious infection) or arrhythmias (atrial fibrillation, uncontrolled tachyarrhythmia) that may impair systolic function 1

Drug Interaction Monitoring

If initiating a weak CYP2C19 inhibitor or moderate CYP3A4 inhibitor in a patient already on Camzyos 1:

• Reduce Camzyos dose by one level immediately 1
• Schedule echocardiogram 4 weeks after inhibitor initiation 1
• Do not up-titrate Camzyos until 12 weeks after inhibitor initiation 1

Treatment Interruption Protocol

If LVEF falls below 50% at any visit 1:

1. Immediately interrupt Camzyos treatment 1
2. Repeat echocardiogram in 2 weeks 1
3. If LVEF remains <50%, repeat echocardiogram every 2 weeks until LVEF ≥50% 1
4. Once LVEF recovers to ≥50%, consider restarting at a lower dose with echocardiogram at 4 weeks 1

Rationale for Intensive Monitoring

Camzyos carries a boxed warning for risk of heart failure due to systolic dysfunction because it reduces LVEF by its mechanism of action as a cardiac myosin inhibitor 1, 2. The drug takes weeks to reach steady-state levels, and genetic variation in metabolism plus drug interactions can cause large differences in drug exposure 1. This pharmacokinetic variability necessitates frequent echocardiographic surveillance to prevent symptomatic heart failure 1.

Common Pitfalls to Avoid

• Never extend monitoring intervals beyond the FDA-mandated schedule, even if the patient appears clinically stable 1
• Do not rely on clinical assessment alone—asymptomatic LVEF decline can occur and requires echocardiographic detection 1
• Avoid initiating Camzyos in patients with baseline LVEF <55%, as they have insufficient cardiac reserve 1
• Do not continue Camzyos if LVEF drops below 50%, even if the patient remains asymptomatic 1