What is the preferred formulation of metoprolol (beta-blocker) for managing hypertrophic obstructive cardiomyopathy (HOCM), metoprolol tartrate or metoprolol succinate?

Metoprolol Formulation for Hypertrophic Obstructive Cardiomyopathy

For hypertrophic obstructive cardiomyopathy, either metoprolol tartrate or metoprolol succinate can be used, as current guidelines do not specify a preferred formulation—however, metoprolol succinate (extended-release) offers the practical advantage of once-daily dosing with more consistent 24-hour beta-blockade. 1

Guideline Recommendations on Beta-Blocker Selection

• The 2024 AHA/ACC/AMSSM/HRS/PACES/SCMR guideline for HCM management recommends "nonvasodilating beta blockers" as first-line therapy for symptomatic obstructive HCM, titrated to effectiveness or maximally tolerated doses, but does not distinguish between metoprolol formulations. 1

• The guideline specifies that beta-blockers should be titrated to a resting heart rate of 60-65 bpm to achieve optimal symptom control and reduction in left ventricular outflow tract obstruction. 2, 3

• Neither the 2024 HCM guideline nor the 2018 hypertension guideline provides a Class I recommendation favoring one metoprolol formulation over the other specifically for HOCM. 1

Key Distinction: Heart Failure vs. HOCM Evidence

• Critical caveat: The heart failure literature clearly distinguishes between formulations—metoprolol succinate (extended-release) demonstrated mortality reduction in heart failure trials, while metoprolol tartrate (immediate-release) did not show the same benefit. 1

• In the COMET trial comparing carvedilol to metoprolol tartrate in heart failure, carvedilol showed superior mortality reduction, but this trial used metoprolol tartrate at doses and formulations different from the metoprolol succinate used in MERIT-HF. 1

• However, these heart failure data should not be directly extrapolated to HOCM, as the pathophysiology and treatment goals differ fundamentally—HOCM management focuses on reducing dynamic obstruction and controlling heart rate, not treating systolic dysfunction. 1

Pharmacokinetic Advantages of Metoprolol Succinate

• Metoprolol succinate extended-release delivers near-constant drug levels over 20 hours, producing even plasma concentrations over 24 hours without the peaks and troughs seen with immediate-release formulations. 4

• This consistent drug delivery maintains cardioselective beta-1 blockade throughout the day at doses up to 200 mg daily, which may provide more stable heart rate control in HOCM patients. 4

• Once-daily dosing with metoprolol succinate improves medication adherence compared to twice-daily metoprolol tartrate dosing. 4

Recent Comparative Evidence

• The 2025 MAPLE-HCM trial compared aficamten (a cardiac myosin inhibitor) to metoprolol in symptomatic obstructive HCM, but used metoprolol at 50-200 mg daily without specifying the formulation in the primary publication. 5, 6

• This trial demonstrated that metoprolol monotherapy actually decreased peak oxygen uptake by -1.2 ml/kg/min over 24 weeks, suggesting beta-blockers may have limitations as monotherapy in some HOCM patients. 5

Practical Dosing Considerations

• Metoprolol tartrate: Typically dosed 100-200 mg divided twice daily for HOCM, as indicated in the 2018 hypertension guideline table. 1

• Metoprolol succinate: Typically dosed 50-200 mg once daily, providing equivalent beta-blockade with simplified dosing. 1

• Both formulations should be titrated gradually to achieve target heart rate of 60-65 bpm at rest, monitoring for symptomatic improvement in dyspnea and chest pain. 1, 3

Common Pitfalls to Avoid

• Do not abruptly discontinue either metoprolol formulation, as this can precipitate rebound tachycardia and worsening symptoms in HOCM patients. 1

• Avoid using metoprolol in combination with non-dihydropyridine calcium channel blockers (verapamil, diltiazem) due to increased risk of bradycardia and heart block. 1

• Do not confuse the heart failure evidence favoring metoprolol succinate with a specific requirement for HOCM—the guideline-directed medical therapy for HOCM does not mandate one formulation over the other. 1

• If beta-blockers prove ineffective or poorly tolerated, substitute with non-dihydropyridine calcium channel blockers (verapamil or diltiazem) rather than switching between metoprolol formulations. 1

Algorithm for Beta-Blocker Selection in HOCM

• Start with either metoprolol formulation based on patient preference for dosing frequency and insurance coverage, as both are acceptable first-line options. 1

• Prefer metoprolol succinate if once-daily dosing would improve adherence or if the patient has difficulty maintaining consistent twice-daily dosing. 4

• Titrate to target heart rate of 60-65 bpm at rest, increasing dose every 1-2 weeks as tolerated. 2, 3

• If inadequate response after reaching maximally tolerated beta-blocker doses, consider adding mavacamten (cardiac myosin inhibitor), disopyramide, or referring for septal reduction therapy rather than switching metoprolol formulations. 1, 2