For a patient with obstructive hypertrophic cardiomyopathy on Camzyos (mavacamten) undergoing elective surgery, when should the drug be continued versus held, and what peri‑operative anesthesia monitoring and management strategies are recommended?

Camzyos and Anesthesia Management

For patients with obstructive HCM on Camzyos undergoing elective surgery, the drug should be held preoperatively due to the critical risk of perioperative hemodynamic instability from excessive myosin inhibition, and traditional negative inotropic agents (beta-blockers or calcium channel blockers) should be continued throughout the perioperative period instead. 1, 2

Rationale for Holding Camzyos

Camzyos (mavacamten) is a cardiac myosin inhibitor that reduces contractility and can cause systolic dysfunction with LVEF reductions below 50% 2. The perioperative setting creates a perfect storm of risk:

• Anesthesia-induced hemodynamic changes (reduced preload, altered afterload, variable heart rates) directly conflict with Camzyos' mechanism of reducing contractility
• The drug takes weeks to reach steady-state and weeks to wash out 2, meaning acute perioperative adjustments are impossible
• Case reports document cardiogenic shock and severe biventricular dysfunction after dose escalations, particularly when complicated by atrial fibrillation or other stressors 3
• The 2024 AHA/ACC perioperative guidelines emphasize continuing established negative inotropic agents (beta-blockers, calcium channel blockers) but make no provision for continuing myosin inhibitors 1

Preoperative Management Algorithm

Timing of discontinuation:

• Hold Camzyos at least 2-4 weeks before elective surgery to allow drug washout (based on its long half-life and time to steady-state) 2
• Obtain baseline echocardiogram to document LVEF and LVOT gradient off Camzyos
• Continue beta-blockers and/or non-dihydropyridine calcium channel blockers without interruption 1

Pre-surgical assessment:

• Confirm LVEF ≥55% before proceeding with surgery
• Document current LVOT gradient status
• Assess volume status and optimize preload

Intraoperative Anesthesia Strategy

The 2024 AHA/ACC guidelines provide explicit management principles for HCM patients 1:

Hemodynamic goals:

• Avoid tachycardia - maintain slower heart rates to ensure adequate LV filling
• Avoid hypovolemia - reduced preload worsens LVOT obstruction
• Avoid hypotension - reduced afterload worsens LVOT obstruction
• Absolutely avoid positive inotropes (dobutamine, epinephrine) - these are harmful and worsen obstruction 1

Monitoring considerations:

• Consider invasive arterial line and central venous pressure monitoring 1
• Strongly consider intraoperative transesophageal echocardiography to evaluate for dynamic LVOT obstruction if hemodynamic instability develops 1, 4

Management of hypotension:

1. First-line: IV fluid boluses to correct hypovolemia 1
2. Second-line: Alpha-agonists (phenylephrine or vasopressin) to increase afterload without increasing contractility 1
3. Avoid beta-agonists which worsen LVOT obstruction
4. Consider IV beta-blockade if obstruction worsens despite fluids and pressors 1

Anesthetic technique:

• Balanced anesthesia is preferable 4
• Avoid propofol as sole anesthetic agent due to vasodilation and myocardial depression 4
• Maintain sinus rhythm where possible due to LV hypertrophy and decreased compliance 1

Postoperative Management

• Continue beta-blockers and calcium channel blockers
• Minimize sympathetic stimulation through adequate pain control
• Avoid excessive diuresis that could reduce preload
• Monitor for atrial fibrillation (high-risk in HCM patients and particularly dangerous with recent Camzyos exposure) 3

Restarting Camzyos

• Wait until patient is hemodynamically stable postoperatively
• Obtain echocardiogram to confirm LVEF ≥55% before restarting 2
• Resume at previous dose or lower if there were perioperative complications
• Ensure close LVEF monitoring per REMS protocol (every 12 weeks initially) 2

Critical Pitfalls to Avoid

1. Do not continue Camzyos through surgery - the inability to rapidly adjust dosing combined with anesthesia-induced hemodynamic changes creates unacceptable risk of cardiogenic shock 3
2. Do not use inotropes for hypotension - this is explicitly harmful in HCM 1
3. Do not allow tachycardia or hypovolemia - both worsen LVOT obstruction 1
4. Do not restart Camzyos without confirming LVEF ≥55% per FDA labeling 2

The evidence strongly supports a conservative approach: hold the myosin inhibitor, rely on traditional negative inotropes, and use meticulous hemodynamic management to avoid the factors that trigger dynamic obstruction.