When starting GDMT in HFrEF patients, do you use Lopressor (metoprolol tartrate) or metoprolol succinate to assess tolerance to beta blockers?

Metoprolol Succinate Should Be Used to Assess Beta Blocker Tolerance in HFrEF Patients

When initiating guideline-directed medical therapy (GDMT) in heart failure with reduced ejection fraction (HFrEF) patients, metoprolol succinate (not metoprolol tartrate/Lopressor) should be used to assess beta blocker tolerance. 1

Evidence-Based Rationale

The 2022 AHA/ACC/HFSA guideline for heart failure management clearly identifies only three beta blockers proven to reduce mortality in HFrEF:

1. Metoprolol succinate (extended-release)
2. Carvedilol
3. Bisoprolol

These specific beta blockers have a Class I, Level of Evidence A recommendation for reducing mortality and hospitalizations in HFrEF patients 1. Metoprolol tartrate (Lopressor) is not among these evidence-based options.

Clinical Approach to Beta Blocker Initiation

Starting Dose and Titration

• Begin with low doses of metoprolol succinate (typically 12.5-25 mg daily)
• Gradually uptitrate every 2 weeks as tolerated
• Target dose: 200 mg daily of metoprolol succinate 1
• Monitor for:
  • Heart rate changes
  • Blood pressure changes
  • Symptoms of worsening heart failure
  • Electrolytes and renal function

Why Metoprolol Succinate Over Tartrate

Metoprolol tartrate (Lopressor) is not recommended for HFrEF management because:

• It lacks the robust clinical trial evidence supporting mortality benefit
• The immediate-release formulation provides less consistent 24-hour beta blockade
• Major clinical trials demonstrating mortality benefit specifically used the succinate formulation 1

Common Pitfalls to Avoid

1. Substituting non-evidence-based beta blockers: Only metoprolol succinate, carvedilol, and bisoprolol have proven mortality benefits in HFrEF 1.

2. Starting with full doses: Begin with low doses and gradually uptitrate to avoid hemodynamic instability.

3. Discontinuing therapy prematurely: If side effects occur, temporarily hold or reduce the dose rather than discontinuing completely. Attempt to restart and uptitrate when stable 1.

4. Abrupt discontinuation: This can lead to clinical deterioration and should be avoided unless absolutely necessary 1.

5. Failure to reach target doses: Every effort should be made to achieve the target dose of 200 mg daily for metoprolol succinate, as clinical trials show dose-dependent improvements in outcomes 1.

Special Considerations

• Hospitalized patients: Beta blockers can be safely initiated before hospital discharge in clinically stable patients not requiring intravenous inotropic therapy 1.

• Patients with contraindications: Document contraindications and reassess frequently for opportunities to initiate therapy when safe.

• Referral to heart failure clinic: Consider referral to specialized heart failure clinics, which are associated with higher rates of appropriate GDMT initiation and titration 2.

By using metoprolol succinate rather than tartrate when initiating beta blocker therapy in HFrEF patients, you're following evidence-based guidelines that have demonstrated clear mortality and morbidity benefits.