Late gadolinium enhancement MRI quantification to predict left ventricular remodeling after acute myocardial infarction

Biomechanics of infarcted left Ventricle-A review of experiments

Myocardial infarction (MI) is one of leading diseases to contribute to annual death rate of 5% in the world. In the past decades, significant work has been devoted to this subject. Biomechanics of infarcted left ventricle (LV) is associated with MI diagnosis, understanding of remodelling, MI micro-structure and biomechanical property characterizations as well as MI therapy design and optimization, but the subject has not been reviewed presently. In the article, biomechanics of infarcted LV was reviewed in terms of experiments achieved in the subject so far. The concerned content includes experimental remodelling, kinematics and kinetics of infarcted LVs. A few important issues were discussed and several essential topics that need to be investigated further were summarized. Microstructure of MI tissue should be observed even carefully and compared between different methods for producing MI scar in the same animal model, and eventually correlated to passive biomechanical property by establishing innovative constitutive laws. More uniaxial or biaxial tensile tests are desirable on MI, border and remote tissues, and viscoelastic property identification should be performed in various time scales. Active contraction experiments on LV wall with MI should be conducted to clarify impaired LV pumping function and supply necessary data to the function modelling. Pressure-volume curves of LV with MI during diastole and systole for the human are also desirable to propose and validate constitutive laws for LV walls with MI.

End-systolic wall stress predicts post-discharge heart failure after acute myocardial infarction

BACKGROUND

Compensatory mechanisms activated after myocardial infarction include an increase in systolic wall stress (SWS) and activation of the neurohormonal system. Nevertheless, left ventricular ejection fraction (LVEF) and infarct size are the established primary predictors of outcome after ST-segment elevation myocardial infarction.

AIMS

To assess the relative impact of various cardiac magnetic resonance (CMR) imaging variables, such as infarct size, LVEF and SWS, on pre- and post-discharge heart failure (HF).

METHODS

CMR was performed in a prospective study involving 169 patients with first ST-segment elevation myocardial infarction. Common CMR findings, such as SWS, were computed.

RESULTS

Mean SWS was 16.3±5.1×10(3)N·m(-2), and was systematically higher in patients exhibiting either pre- or post-discharge HF (18.9±5.7 and 21.3±7.6×10(3) N·m(-2), respectively). SWS was moderately related to initial infarct size (r=0.405; P <0.001). In total, 28 patients presented with HF during the hospitalization phase and 14 during follow-up, with a median time of event of 93 days (25th-75th percentiles, 29-139.25 days). The univariate predictors of HF were age, LVEF, infarct size, SWS, microvascular obstruction, anterior infarction and heart rate at admission. Multivariable analysis revealed infarct size and age to be the predictors of predischarge HF, while SWS and heart rate at admission predicted post-discharge HF. The greatest SWS quartile provided a negative predictive value of 95.9%.

CONCLUSION

Regardless of LVEF and infarct size, SWS was shown to be an independent predictor of post-discharge HF after ST-segment elevation myocardial infarction.