Post-infarct evolution of ventricular and myocardial function

Adverse ventricular remodeling following acute myocardial infarction (MI) may induce ventricular dilation, fibrosis, and loss of global contractile function, possibly resulting in heart failure (HF). Understanding the relation between the time-dependent changes in material properties of the myocardium and the contractile function of the heart may further our understanding of the development of HF post-MI and guide the development of novel therapies. A finite element model of cardiac mechanics was used to model MI in a thick-walled truncated ellipsoidal geometry. Infarct core and border zone comprised 9.6 and 8.1% of the LV wall volume, respectively. Acute MI was modeled by inhibiting active stress generation. Chronic MI was modeled by the additional effect of infarct material stiffening, wall thinning and fiber reorientation. In acute MI, stroke work decreased by 25%. In the infarct core, fiber stress was reduced but fiber strain was increased, depending on the degree of infarct stiffening. Fiber work density was equal to zero. Healthy tissue adjacent to the infarct showed decreased work density depending on the degree of infarct stiffness and the orientation of the myofibers with respect to the infarct region. Thinning of the wall partially restored this loss in work density while the effects of fiber reorientation were minimal. We found that the relative loss in pump function in the infarcted heart exceeds the relative loss in healthy myocardial tissue due to impaired mechanical function in healthy tissue adjacent to the infarct. Infarct stiffening, wall thinning and fiber reorientation did not affect pump function but did affect the distribution of work density in tissue adjacent to the infarct.

The Role of the Notch Signaling Pathway in Recovery of Cardiac Function after Myocardial Infarction

Myocardial infarction (MI) is a pathological process, evidencing as massive death of cardiomyocytes associated with hypoxic and oxidative stress. The formation of areas of fibrosis ultimately leads to heart failure. There are some mechanisms that contribute to the functional repair of the heart. In most mammals, including humans, the Notch signaling pathway has cardioprotective effects. It is involved in the formation of the heart in embryogenesis and in the restoration of cardiac function after MI due to: (1) reducing oxidative stress; (2) prevention of apoptosis; (3) regulation of inflammation; (4) containment of fibrosis and hypertrophy of cardiomyocytes; (5) tissue revascularization; and (6) regulation of proliferation and differentiation of cardiomyocytes. In addition, the Notch signaling pathway interacts with other signaling cascades involved in the pathogenesis of MI and subsequent cardiac repair. In this review, we consider the Notch signaling pathway as a potential target for therapeutic approaches aimed at improving cardiac recovery after MI.

Left Ventricular Remodeling after Myocardial Infarction: From Physiopathology to Treatment

Myocardial infarction (MI) is the leading cause of death and morbidity worldwide, with an incidence relatively high in developed countries and rapidly growing in developing countries. The most common cause of MI is the rupture of an atherosclerotic plaque with subsequent thrombotic occlusion in the coronary circulation. This causes cardiomyocyte death and myocardial necrosis, with subsequent inflammation and fibrosis. Current therapies aim to restore coronary flow by thrombus dissolution with pharmaceutical treatment and/or intravascular stent implantation and to counteract neurohormonal activation. Despite these therapies, the injury caused by myocardial ischemia leads to left ventricular remodeling; this process involves changes in cardiac geometry, dimension and function and eventually progression to heart failure (HF). This review describes the pathophysiological mechanism that leads to cardiac remodeling and the therapeutic strategies with a role in slowing the progression of remodeling and improving cardiac structure and function.

Prediction of Adverse Post-Infarction Left Ventricular Remodeling Using a Multivariate Regression Model

Background. In order to provide personalized medicine and improve cardiovascular outcomes, a method for predicting adverse left ventricular remodeling (ALVR) after ST-segment elevation myocardial infarction (STEMI) is needed. Methods. A total of 125 STEMI patients, mean age 51.2 (95% CI 49.6; 52.7) years were prospectively enrolled. The clinical, laboratory, and instrumental examinations were performed between the 7th and 9th day, and after 24 and 48 weeks, including plasma analysis of brain natriuretic peptide (BNP), transthoracic echocardiography, analysis of left ventricular-arterial coupling, applanation tonometry, ultrasound examination of the common carotid arteries with RF signal amplification. Results. Patients were divided into 2 groups according to echocardiography: “ALVR” (n = 63)—end-diastolic volume index (EDVI) >20% and/or end-systolic volume index (ESVI) >15% after 24 weeks compared with initial values; “non-ALVR” (n = 62)—EDVI <20% and ESVI <15%. In the ALVR group, hard endpoints (recurrent myocardial infarction, unstable angina, hospitalization for decompensated heart failure, ventricular arrhythmias, cardiac surgery, cardiovascular death) were detected in 19 people (30%). In the non-ALVR group, hard endpoints were noted in 3 patients (5%). The odds ratio of developing an adverse outcome in ALVR vs. non-ALVR group was 8.5 (95% CI 2.4−30.5) (p = 0.0004). According to the multivariate analysis, the contribution of each of the indicators to the relative risk (RR) of adverse cardiac remodeling: waist circumference, RR = 1.02 (95% CI 1.001−1.05) (p = 0.042), plasma BNP—RR = 1.81 (95% CI 1.05−3.13) (p = 0.033), arterial elastance to left ventricular end-systolic elastance (Ea/Ees)—RR = 1.96 (95% CI 1.11−3.46) (p = 0.020). Conclusion. Determining ALVR status in early stages of the disease can accurately predict and stratify the risk of adverse outcomes in STEMI patients.

Late Versus Early Myocardial Remodeling After Acute Myocardial Infarction: A Comparative Review on Mechanistic Insights and Clinical Implications

In the setting of acute myocardial infarction (AMI), adverse myocardial remodeling (AMR) has been universally regarded as an early-onset phenomenon generally arising within the first few weeks (usually within days in the infarct zone) following myocardial injury. On the other hand, onset of cardiac morphological changes in this setting may potentially extend far beyond this time frame (usually beyond several months after the index AMI), suggesting a prolonged latent period in certain cases. In clinical practice, this delayed form of post-AMI remodeling, namely late AMR, has emerged as an interesting and underrecognized phenomenon with poorly understood mechanisms. Notably, systemic inflammation and associated growth factors seem to play a pivotal role in this setting. Accordingly, the present article primarily aims to discuss potential mechanisms and clinical implications of late AMR (in a comparative manner with its classical early counterpart) among AMI survivors along with a particular emphasis on potential benefits of certain anti-inflammatory strategies in this setting.