Early ventricular restraint after myocardial infarction: extent of the wrap determines the outcome of remodeling.
BACKGROUND
Early infarct expansion initiates adverse remodeling, leads to left ventricular dilatation and portends a poor long-term outcome. Early mechanical prevention of infarct expansion has been proposed as a method to improve remodeling, but the extent of ventricular restraint necessary to optimize the salutary effect is not known. We tested the hypothesis that left ventricular restraint (wrap) is superior to infarct stiffening (patch).


METHODS
Infarction of 20% to 25% of the left ventricle was induced by coronary ligation in 69 sheep. Infarcts were either anteroapical (n = 33) or posterobasal (n = 36). Animals with each infarct received either no treatment (anteroapical, n = 26; posterobasal, n = 17), infarct stiffening with a localized Marlex mesh patch (posterobasal, n = 9) or left ventricular wrapping with Merseline mesh (anteroapical, n = 7; posterobasal, n = 10). End-systolic volume, end-diastolic volume, end-systolic muscle to cavity area ratio, left ventricular sphericity, ejection fraction, and degree of mitral regurgitation as determined by quantitative echocardiography were assessed before infarction and at 2, 5, and 8 weeks after infarction to evaluate the extent of left ventricular remodeling.


RESULTS
Control animals in both groups experienced adverse remodeling. Anteroapical infarct animals developed large left ventricular aneurysms and the posterobasal infarct animals developed severe mitral regurgitation. Early infarct stiffening did not significantly improve any aspect of remodeling due to the posterobasal infarct. Early left ventricular wrapping significantly improved remodeling after both types of infarctions.


CONCLUSIONS
Early left ventricular wrapping attenuates infarct expansion and has a salutary effect on remodeling. Simple infarct stiffening alone is not effective.
Enomoto
Yoshiharu
Y
Harrison Department of Surgical Research, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
Gorman
Joseph H
JH
Moainie
Sina L
SL
Jackson
Benjamin M
BM
Parish
Landi M
LM
Plappert
Theodore
T
Zeeshan
Ahmad
A
St John-Sutton
Martin G
MG
Gorman
Robert C
RC
D000818:Animals; D009203:Myocardial Infarction / Q000150:complications / Q000601:surgery*; D011126:Polypropylenes; D012756:Sheep; D013526:Surgical Mesh; D013997:Time Factors; D020257:Ventricular Remodeling
D011126:Polypropylenes