Relevance of the ventricular remodeling pattern in the model of myocardial infarction in rats.

Background: The relevance of the remodeling pattern in the model of infarcted rats is not known.

Objective: To analyze the presence of different patterns of remodeling in this model and its functional implications.

Methods: Infarcted rats (n=47) have been divided according to the geometry pattern, analyzed by echocardiogram: normal (normal mass index and normal relative thickness), concentric remodeling (normal mass index and increased relative thickness), concentric hypertrophy (increased mass index and increased relative thickness) and eccentric hypertrophy (increased mass index and normal relative thickness). Data are median and interquartile range.

Results: Infarcted rats showed only two of the four geometric patterns: normal pattern (15%) and eccentric hypertrophy - EH (85%). Groups of normal pattern and EH showed no differences in the values of fractional area change (Normal = 32.1 - 28.8 to 50.7; EH = 31.3 - 26.5 to 36.7; p = 0.343). Out of the infarcted animals, 34 (74%) had systolic dysfunction, detected by fractional area change. Considering these two geometry patterns, 77% of animals with eccentric hypertrophy and 57% with normal geometry presented systolic dysfunction (p=0.355). The relative wall thickness, the geometric patterns and the body mass index were not predictors of ventricular dysfunction (p> 0.05). On the other hand, infarct size was a predictive factor for ventricular dysfunction in univariate analysis (p<0.001) and multivariate analysis (p = 0.004).

Conclusion: Rats that underwent coronary occlusion showed two different patterns of remodeling, which do not constitute a predictor of ventricular dysfunction.