IV Metoprolol Did Not Reduce Infarct Size in Patients With MI Undergoing Stenting

MedicalResearch.com Interview with:
Vincent Roolvink, MD
Isala hospital, Department of Cardiology
Zwolle, The Netherlands

Medical Research: What is the background for this study?

Dr. Roolvink: The goal of the trial was to assess the safety and efficacy of early administration of intravenous (IV) metoprolol in patients presenting with ST-elevation myocardial infarction (STEMI) and scheduled for primary percutaneous coronary intervention (PCI).

Medical Research: What was the study design?

Dr. Roolvink: Patients were randomized in a 1:1 fashion to receive IV bolus metoprolol 5 mg (n = 336) or matching placebo (n = 347). Two bolus doses were given: the first one in the ambulance, and second at the PCI hospital at the catheterization laboratory before the PCI procedure only if systolic blood pressure (BP) was >100 mm Hg and heart rate was >60 bpm.

  • Total number of enrollees: 683
  • Duration of follow-up: 30 days
  • Mean patient age: 62 years
  • Percentage female: 25%

Other salient features/characteristics:

  • Diabetes: 16%
  • Beta-blocker use at home prior to MI: 19%
  • Anterior STEMI: 51%
  • Early presentation within 6 hours: 92%
  • Mean systolic BP/diastolic BP at admission: 137.6/82.5 mm Hg
  • Mean heart rate at admission: 76.5 bpm
  • Multivessel disease: 44%

Inclusion criteria:

  • Patients aged >18 years with symptoms of acute STEMI for >30 minutes but <12 hours
  • Confirmed diagnosis of STEMI with plan for primary PCI

Exclusion criteria:

  • Killip class III and IV
  • Systolic BP <100 mm Hg
  • Heart rate <60 bpm
  • Type II and III atrioventricular (AV) block
  • History of previous MI
  • Known asthma, pacemaker, or implantable cardioverter-defibrillator
  • Pregnancy or breast-feeding

Medical Research: What are the main findings?

Dr. Roolvink: Primary endpoint, infarct size on delayed enhancement cardiac magnetic resonance (CMR) at 30 days, for metoprolol vs. placebo: 15.3% vs. 14.9%, p = 0.61

Secondary outcomes (for metoprolol vs. placebo):

  • Left ventricular ejection fraction on CMR: 51% vs. 51.7%, p = 0.68
  • Severe bradycardia: 1.5% vs. 0.6%, p = 0.28
  • Cardiogenic shock: 0.6% vs. 0.3%, p = 0.62
  • Ventricular arrhythmia in acute phase: 3.6% vs. 6.9%, p = 0.05
  • Thirty-day major adverse cardiac events: 6.2% vs. 6.9%, p = 0.72

Medical Research: How should these findings be interpreted?

Dr. Roolvink: The results of this trial indicate that early routine administration of IV metoprolol is not beneficial in reducing infarct size in patients presenting with STEMI and undergoing primary PCI. Patients in cardiogenic shock or at high risk were excluded, as were patients with advanced AV blocks. There was no clear safety signal with early administration of IV beta-blockers, as noted in the larger COMMIT CC2 trial. Another smaller trial, METOCARD-CNIC, had observed a potential benefit in patients with anterior STEMI, but was not noted on subgroup analysis in this trial.


Early Administration of intravenous Beta blockers in patients with ST-elevation myocardial infarction before primary PCI

Vincent Roolvink, MD et al Available online 3 April 2016
Journal of the American College of Cardiology

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Last Updated on April 14, 2016 by Marie Benz MD FAAD