Left ventricular dilatation after myocardial infarction: ACE inhibitors, beta-blockers, or both?

Left ventricular remodeling after the first myocardial infarction in association with LGALS-3 neighbouring variants rs2274273 and rs17128183 and its relative mRNA expression: a prospective study

Post-infarct left ventricular remodeling (LVR) process increases the risk of heart failure (HF). Circulating galectin-3 has been associated with fibrosis, inflammation and cardiac dysfunction during the remodeling process after myocardial infarction (MI). The aims of this prospective case study were to investigate the association of potentially functional variants in the vicinity of LGALS-3 locus, rs2274273 and rs17128183 with maladaptive LVR and whether these variants could affect LGALS-3 mRNA expression in peripheral blood mononuclear cells of patients 6 months after the first MI. This study encompassed 167 patients with acute MI that were followed up for 6 months. Evidence of LVR was obtained by repeated 2D Doppler echocardiography. Rs2274273, rs17128183 and LGALS-3 mRNA expression were detected by TaqMan^® technology. Rs2274273 and rs17128183 rare allele bearing genotypes, according to the dominant model (CT+TT vs. CC and AG+GG vs. AA, respectively), were significantly and independently associated with maladaptive LVR (adjusted OR = 3.02, P = 0.016; adjusted OR = 3.14, P = 0.019, respectively) and higher LGALS-3 mRNA expression (fold induction 1.203, P = 0.03 and 1.214, P = 0.03, respectively). Our exploratory results suggest that rs2274273 and rs17128183 variants affect LGALS-3 mRNA and bear the risk for maladaptive LVR post-MI remodeling. Further replication and validation in a larger group of patients is inevitable.

Symptom-to-balloon time and myocardial blush grade are predictors of left ventricular remodelling after successful primary percutaneous coronary intervention

Introduction:

In patients with ST-segment elevation myocardial infarction (STEMI), successful primary percutaneous coronary intervention (PCI) was found to be useful in earlier restoration of TIMI flow 3. However, the incidence of left ventricular (LV) dilatation and remodelling after successful primary PCI is still high. We aimed to determine the independent predictors of LV remodelling after successful primary PCI for patients with first STEMI.

Methods:

We included 232 STEMI patients treated with primary PCI. Echocardiography was done on the day of PCI and after six months. LV remodelling was defined as ≥ 20% increase in the six-month left ventricular end-diastolic volume (LVEDV).

Results:

In patients with remodelling, symptom-to-door and symptom-to-balloon times were significantly longer (p < 0.00001 for each), initial ejection fraction (EF) was significantly lower (p = 0.044), six-month LVEDV, left ventricular end-systolic volume (LVESV) and LVEDV increase were significantly higher, and EF was significantly lower (p < 0.00001 for each). Mean myocardial blush grade (MBG) was significantly lower in patients with remodelling (p < 0.00001). There was a significant positive correlation between LVEDV increase and both symptom-to-balloon time (r = 0.603, p < 0.00001) and symptom-to-door time (r = 0.564, p < 0.00001), and a significant negative correlation between LVEDV increase and MBG (r = –0.447, p < 0.00001). Logistic regression showed that the independent predictors of LV remodelling were symptom-to-balloon time (p = 0.00068), symptom to door time (p = 0.0013) and MBG (p = 0.0057).

Conclusion:

Symptom-to-door time, symptom-to-balloon time and MBG were the only significant predictors of LV remodelling.

Role of oxidative stress in cardiac remodelling after myocardial infarction

Recovery from myocardial infarction is associated with a series of alterations in heart structure and function, collectively known as cardiac remodelling, which play a major role in the subsequent development of heart failure. Early remodelling involves infarct scar formation in the ischaemic zone whereas subsequent ventricular remodelling affects mainly the viable non-infarcted myocardium with especially profound alterations in the extracellular matrix. There is growing evidence for a role of oxidative stress and redox signalling in the processes underlying cardiac remodelling. Reactive oxygen species are a group of highly reactive molecules which have the potential to modulate several biological processes as well as cause tissue damage and dysfunction. Their effects can be beneficial or deleterious, depending on the concentrations produced, the site of production, and the overall redox status of the cell. Reactive oxygen species can be generated by all cardiovascular cell types. Under pathophysiological conditions, major enzymatic sources appear to be mitochondria, xanthine oxidase and the non-phagocytic NADPH oxidases. In this review, we outline the mechanisms underlying the progression of early and late cardiac remodelling with particular focus on the role of oxidative stress and the potential sources of reactive oxygen species which may be involved.

Renin-angiotensin blockade attenuates cardiac myofibrillar remodelling in chronic diabetes

Previous studies have shown that the renin-angiotensin system (RAS) is activated in diabetes and this may contribute to the subcellular remodelling and heart dysfunction in this disease. Therefore, we examined the effects of RAS blockade by enalapril, an angiotensin-converting enzyme inhibitor, and losartan, an angiotensin receptor AT1 antagonist, on cardiac function, myofibrillar and myosin ATPase activity as well as myosin heavy chain (MHC) isozyme expression in diabetic hearts. Diabetes was induced in rats by a single injection of streptozotocin (65 mg/kg; i.v.) and these animals were treated with and without enalapril (10 mg/kg/day; oral) or losartan (20 mg/kg/day; oral) for 8 weeks. Enalapril or losartan prevented the depressions in left ventricular rate of pressure development, rate of pressure decay and ventricular weight seen in diabetic animals. Both drugs also attenuated the decrease in myofibrillar Ca2+-ATPase, Mg2+-ATPase and myosin ATPase activity seen in diabetic rats. The diabetes-induced increase in beta-MHC content and gene expression as well as the decrease in alpha-MHC content and mRNA levels were also prevented by enalapril and losartan. These results suggest the occurrence of myofibrillar remodelling in diabetic cardiomyopathy and provide evidence that the beneficial effects of RAS blockade in diabetes may be associated with attenuation of myofibrillar remodelling in the heart.

Partial prevention of changes in SR gene expression in congestive heart failure due to myocardial infarction by enalapril or losartan

Although activation of the renin-angiotensin system (RAS) is known to produce ventricular remodeling and congestive heart failure (CHF), its role in inducing changes in the sarcoplasmic reticulum (SR) protein and gene expression in CHF is not fully understood. In this study, CHF was induced in rats by ligation of the left coronary artery for 3 weeks and then the animals were treated orally with or without an angiotensin converting enzyme inhibitor, enalapril (10 mg/kg/day) or an angiotensin II receptor antagonist, losartan (20 mg/kg/day) for 4 weeks. Sham-operated animals were used as control. The animals were hemodynamically assessed and protein content as well as gene expression of SR Ca(2+)-release channel (ryanodine receptor, RYR), Ca(2+)-pump ATPase (SERCA2), phospholamban (PLB) and calsequestrin (CQS) were determined in the left ventricle (LV). The infarcted animals showed cardiac hypertrophy, lung congestion, depression in LV +dP/dt and -dP/dt, as well as increase in LV end diastolic pressure. Both protein content and mRNA levels for RYR, SERCA2 and PLB were decreased without any changes in CQS in the failing heart. These alterations in LV function as well as SR protein and gene expression in CHF were partially prevented by treatment with enalapril or losartan. The results suggest that partial improvement in LV function by enalapril and losartan treatments may be due to partial prevention of changes in SR protein and gene expression in CHF and that these effects may be due to blockade of the RAS.