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Magnesium sulfate reduces myocardial infarct size when administered before but not after coronary reperfusion in a
C W Christensen1, M A Rieder, E L Silverstein
1University of Wisconsin Medical School, Sinai Samaritan Medical Center, Milwaukee 53201-0342, USA.
Background:
The role of magnesium in treating acute myocardial infarction (AMI) has been controversial. Several small clinical trials indicate that magnesium may have a role in treating AMI early, whereas the other results suggest that magnesium is of questionable benefit.
Methods And Results:
We looked at the effect of magnesium on infarct size (IS) when given during a coronary occlusion and after reperfusion. Magnesium sulfate (6-mEq bolus plus 2 mEq/h for 5 hours) was given at 15 or 45 minutes of coronary occlusion or 15 minutes of reperfusion. The left anterior descending coronary artery was occluded for 90 minutes, followed by 300 minutes of reperfusion. IS to area at risk (IS/AR) was measured by planimetry after triphenyltetrazolium chloride staining. Collateral myocardial blood flow was measured with radioactive microspheres. The IS/AR ratio in the control group was 52.3 +/- 19.6% compared with 20.5 +/- 11.7% and 21.3 +/- 6.5% at 15 and 45 minutes of occlusion, respectively (P < .05). There were no significant differences in the reduction in IS at 15 and 45 minutes of occlusion. Although there was a reduction in the IS when magnesium was administered during reperfusion (38.2 +/- 13.4%), it was not statistically significant. There was no significant difference in the AR relative to the total left ventricular weight between the four groups.
Conclusions:
The data suggest that magnesium infusion during a coronary occlusion has a significant benefit in reducing the IS in this model. Magnesium may have a beneficial clinical role in AMI, especially if administered before reperfusion as a bolus followed by a constant infusion.
Insights
Magnesium administration during coronary occlusion significantly reduces infarct size in a myocardial infarction model. Early intervention with magnesium before reperfusion may offer clinical benefits for acute myocardial infarction (AMI).
Area of Science:
- Cardiovascular Research
- Pharmacology
- Myocardial Infarction Treatment
Background:
- The role of magnesium in acute myocardial infarction (AMI) treatment remains controversial.
- Previous studies show conflicting results regarding magnesium's efficacy in early AMI management.
- This study investigates magnesium's effect on infarct size during coronary occlusion and reperfusion.
Purpose of the Study:
- To evaluate the impact of magnesium sulfate on infarct size (IS) in a myocardial infarction model.
- To determine the optimal timing for magnesium administration—during occlusion versus reperfusion.
Main Methods:
- Magnesium sulfate was administered as a bolus plus infusion at different time points: 15 or 45 minutes of coronary occlusion, or 15 minutes of reperfusion.
- The left anterior descending coronary artery was occluded for 90 minutes, followed by 300 minutes of reperfusion.
- Infarct size to area at risk (IS/AR) was quantified using triphenyltetrazolium chloride staining and planimetry.
Main Results:
- Magnesium administration at 15 and 45 minutes of coronary occlusion significantly reduced IS/AR compared to controls (20.5% and 21.3% vs. 52.3%, P < .05).
- No significant difference in IS reduction was observed between the 15-minute and 45-minute occlusion groups.
- Magnesium given during reperfusion showed a trend towards reducing IS (38.2%), but this was not statistically significant.
Conclusions:
- Magnesium infusion during coronary occlusion demonstrates significant benefit in reducing infarct size in this experimental model.
- The findings suggest a potential beneficial clinical role for magnesium in AMI, particularly when administered before reperfusion.
- Optimal timing involves a bolus followed by continuous infusion prior to reperfusion.