Steroid administration after myocardial infarction promotes early infarct expansion. A study in the rat.
Key result
High-dose methylprednisolone administered within 24 hours after transmural myocardial infarction in rats significantly decreased infarct wall thickness to 0.99 mm compared to 1.35 mm with saline (P<0.001).
Why the study?
Does methylprednisolone administration after myocardial infarction worsen early infarct expansion in a rat model?
Population
Rats undergoing either transmural infarction by left coronary ligation or sham operation
Comparison
Methylprednisolone 50 mg/kg i.p. x 4 within 24 h… vs Saline treatment
Design
Preclinical, Randomized
Follow-up
Up to 7 days
Authors
Discussion
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Member takes
Implication
High-dose methylprednisolone may promote early infarct expansion in rat MI models; leaves open relevance to human postinfarction remodeling.
Structured PICO
Does methylprednisolone administration after myocardial infarction worsen early infarct expansion in a rat model?
P
Population
Rats undergoing either transmural infarction by left coronary ligation or sham operation
I
Intervention
Methylprednisolone 50 mg/kg i.p. x 4 within 24 h after operation
C
Comparator
Saline treatment
O
Outcome
Infarct wall thickness at 3 days and 7 dayssurrogate
Main Result
Absolute Event Rate: 0.99% vs 1.35%
p-value: p=<0.001
High-dose methylprednisolone given within 24 hours after myocardial infarction promotes early infarct expansion by increasing the slippage of necrotic myocytes before collagen deposition begins.
Limitations
- Masson's trichrome stain may not be sensitive enough to detect small amounts of collagen laid down by rare fibroblasts at the margins of 3-day-old infarcts.
- Potential overestimation of total cell counts through failure to recognize branched myocytes.
Cite This Study
Mannisi et al. (1987) studied Myocardial infarction (n=128). Methylprednisolone vs. Saline placebo was evaluated on Infarct wall thickness at 3 days (mm) (p=<0.001). High-dose methylprednisolone administered within 24 hours after transmural myocardial infarction in rats significantly decreased infarct wall thickness to 0.99 mm compared to 1.35 mm with saline (P<0.001).