Key result
Large MIs with marked LV dilatation are linked to ~16% yearly mortality versus smaller infarcts.
Why the study?
Left ventricular remodeling after myocardial infarction involves structural and functional changes in the residual myocardium that impact clinical outcomes, but detailed assessment methods and prognostic significance require clarification.
Left ventricular remodeling after myocardial infarction, characterized by geometric and structural changes, is strongly associated with unfavorable clinical outcomes and increased mortality.
High-mortality large-MI patients with marked LV dilatation warrant intensified surveillance; leaves open whether remodeling therapies improve outcomes.
Changes of the left ventricle after myocardial infarction are characterized by geometric, structural, and vascular alterations, which have been summarized under the term "remodeling". This process takes place in the infarct region as well as in the surviving myocardium. Depending on to the size of infarction and the degree of neurohumoral activation, the left ventricle demonstrates diastolic dysfunction which may finally lead to systolic failure. The residual myocardium develops progressive myocyte hypertrophy and interstitial fibrosis. These structural alterations are due to changes in loading conditions and stimulation of the neurohumoral system with an activation of local paracrine and autocrine factors. Myocardial function can be assessed by different non-invasive (echocardiography, radionuclide ventriculography, magnetic resonance imaging, etc.) or invasive methods (e.g., simultaneous pressure-volume measurements). "Myocardial tagging" based on magnetic resonance imaging allows the assessment of 3D-motion of the left ventricle by labelling specific myocardial regions with a rectangular grid. A systolic "wringing" motion with clock-wise rotation at the base and counter-clockwise rotation at the apex has been described in normal subjects. In the ischemic myocardium, delayed relaxation with a prolonged back-rotation (untwisting) has been reported during early diastole, whereas decreased systolic contraction with delayed diastolic rotation has been observed in non-Q-wave infarction. In patients with anterolateral aneurysms, a complete loss of systolic rotation has been demonstrated. The prognostic significance of LV "remodeling" has been emphasized by several authors: The size of infarction, LV volume, LV ejection fraction, as well as the degree of neurohumoral activation have been identified as being associated with an unfavorable clinical outcome. Yearly mortality rates have been reported to range between 15 and 17% in patients with large infarcts and marked LV dilatation and between 3 and 7% in patients with small to medium-sized infarcts.
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Matter et al. (1997) conducted a review in Myocardial infarction. Left ventricular remodeling and large infarct size vs. Small to medium-sized infarcts was evaluated. Large myocardial infarcts with marked left ventricular dilatation are associated with yearly mortality rates of 15-17%, compared to 3-7% in patients with small to medium-sized infarcts.
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