Beneficial effects of angiotensin-converting enzyme inhibitor and nitrate association on left ventricular remodeling in patients with large acute myocardial infarction: the Delapril Remodeling after Acute Myocardial Infarction (DRAMI) trial

Signaling pathways and targeted therapy for myocardial infarction

Although the treatment of myocardial infarction (MI) has improved considerably, it is still a worldwide disease with high morbidity and high mortality. Whilst there is still a long way to go for discovering ideal treatments, therapeutic strategies committed to cardioprotection and cardiac repair following cardiac ischemia are emerging. Evidence of pathological characteristics in MI illustrates cell signaling pathways that participate in the survival, proliferation, apoptosis, autophagy of cardiomyocytes, endothelial cells, fibroblasts, monocytes, and stem cells. These signaling pathways include the key players in inflammation response, e.g., NLRP3/caspase-1 and TLR4/MyD88/NF-κB; the crucial mediators in oxidative stress and apoptosis, for instance, Notch, Hippo/YAP, RhoA/ROCK, Nrf2/HO-1, and Sonic hedgehog; the controller of myocardial fibrosis such as TGF-β/SMADs and Wnt/β-catenin; and the main regulator of angiogenesis, PI3K/Akt, MAPK, JAK/STAT, Sonic hedgehog, etc. Since signaling pathways play an important role in administering the process of MI, aiming at targeting these aberrant signaling pathways and improving the pathological manifestations in MI is indispensable and promising. Hence, drug therapy, gene therapy, protein therapy, cell therapy, and exosome therapy have been emerging and are known as novel therapies. In this review, we summarize the therapeutic strategies for MI by regulating these associated pathways, which contribute to inhibiting cardiomyocytes death, attenuating inflammation, enhancing angiogenesis, etc. so as to repair and re-functionalize damaged hearts.

ACE Inhibition Modulates Myeloid Hematopoiesis after Acute Myocardial Infarction and Reduces Cardiac and Vascular Inflammation in Ischemic Heart Failure

Aims: Angiotensin-converting-enzyme inhibitors (ACE inhibitors) are a cornerstone of drug therapy after myocardial infarction (MI) and improve left ventricular function and survival. We aimed to elucidate the impact of early treatment with the ACE inhibitor ramipril on the hematopoietic response after MI, as well as on the chronic systemic and vascular inflammation. Methods and Results: In a mouse model of MI, induced by permanent ligation of the left anterior descending artery, immediate initiation of treatment with ramipril (10 mg/k/d via drinking water) reduced cardiac inflammation and the number of circulating inflammatory monocytes, whereas left ventricular function was not altered significantly, respectively. This effect was accompanied by enhanced retention of hematopoietic stem cells, Lin⁻Sca1⁻c-Kit⁺CD34⁺CD16/32⁺ granulocyte–macrophage progenitors (GMP) and Lin⁻Sca1⁻c-Kit⁺CD150⁻CD48⁻ multipotent progenitors (MPP) in the bone marrow, with an upregulation of the niche factors Angiopoetin 1 and Kitl at 7 d post MI. Long-term ACE inhibition for 28 d limited vascular inflammation, particularly the infiltration of Ly6C^high monocytes/macrophages, and reduced superoxide formation, resulting in improved endothelial function in mice with ischemic heart failure. Conclusion: ACE inhibition modulates the myeloid inflammatory response after MI due to the retention of myeloid precursor cells in their bone marrow reservoir. This results in a reduction in cardiac and vascular inflammation with improvement in survival after MI.

Side effects of using nitrates to treat heart failure and the acute coronary syndromes, unstable angina and acute myocardial infarction

Nitrates are potent venous dilators and anti-ischemic agents. They are widely used for the relief of chest pain and pulmonary congestion in patients with acute coronary syndromes and heart failure. Nitrates, however, do not reduce mortality in patients with acute coronary syndromes. Combination of nitrates and hydralazine when given in addition to beta-blockers and angiotensin-converting enzyme (ACE) inhibitors reduce mortality and heart failure hospitalizations in patients with heart failure due to left ventricular systolic dysfunction who are of African-American origin. Side effects during nitrate therapy are common but are less well described in the literature compared with the reported side effects in patients with stable angina pectoris. The reported incidence of side effects varies highly among different studies and among various disease states. Headache is the most commonly reported side effect with an incidence of 12% in acute heart failure, 41-73% in chronic heart failure, 3-19% in unstable angina and 2-26% in acute myocardial infarction. The reported incidence of hypotension also differs: 5-10% in acute heart failure, 20% in chronic heart failure, 9% in unstable angina and < 1-48% in acute myocardial infarction, with the incidence being much higher with concomitant nitrate therapy plus angiotensin-converting enzyme inhibitors. Reported incidence of dizziness is as low as 1% in patients with acute myocardial infarction to as high as 29% in patients with heart failure. Severe headaches and/or symptomatic hypotension may necessitate discontinuation of nitrate therapy. Severe life threatening hypotension or even death may occur when nitrates are used in patients with acute inferior myocardial infarction associated with right ventricular dysfunction or infarction, or with concomitant use of phosphodiesterase-5 inhibitors or N-acetylcysteine. Despite the disturbing observational reports in the literature that continuous and prolonged use of nitrates may lead to increased mortality and recurrent myocardial infarction in patients with stable coronary artery disease, no such adverse effects of nitrates have been reported in the large randomized trials in patients with acute myocardial infarction or chronic heart failure.