Do angiotensin receptor blockers prevent myocardial infarctions as well as other initial therapies?

Renin Angiotensin Blockers and Cardiac Protection: From Basis to Clinical Trials

Despite a similar beneficial effect on blood pressure lowering observed with angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II type 1 receptor (AT1R) blocker (ARBs), several clinical trials and meta-analyses have reported higher cardiovascular mortality and lower protection against myocardial infarction with ARBs when compared with ACEIs. The European guidelines for the management of coronary syndromes and European guidelines on diabetes recommend using ARBs in patients who are intolerant to ACEIs. We reviewed the main pharmacological differences between ACEIs and ARBs, which could provide insights into the differences in the cardiac protection offered by these 2 drug classes. The effect of ACEIs on the tissue and plasma levels of bradykinin and on nitric oxide production and bioavailability is specific to the mechanism of action of ACEIs; it could account for the different effects of ACEIs and ARBs on endothelial function, atherogenesis, and fibrinolysis. Moreover, chronic blockade of AT1 receptors by ARBs induces a significant and permanent increase in plasma angiotensin II and an overstimulation of its still available receptors. In animal models, AT4 receptors have vasoconstrictive, proliferative, and inflammatory effects. Moreover, in models with kidney damage, atherosclerosis, and/or senescence, activation of AT2 receptors could have deleterious fibrotic, vasoconstrictive, and hypertrophic effects and seems prudent and reasonable to reserve the use of ARBs for patients who have presented intolerance to ACE inhibitors.

Risk of cancer with angiotensin-receptor blockers increases with increasing cumulative exposure: Meta-regression analysis of randomized trials

Angiotensin-receptor blockers (ARBs) are a class of drugs approved for the treatment of several common conditions, such as hypertension and heart failure. Recently, regulatory agencies have started to identify possibly carcinogenic nitrosamines and azido compounds in a multitude of formulations of several ARBs, resulting in progressive recalls. Furthermore, data from several randomized controlled trials suggested that there is also a clinically increased risk of cancer and specifically lung cancer with ARBs; whereas other trials suggested no increased risk. The purpose of this analysis was to provide additional insight into the ARB-cancer link by examining whether there is a relationship between degree of cumulative exposure to ARBs and risk of cancer in randomized trials. Trial-level data from ARB Trialists Collaboration including 15 randomized controlled trials was extracted and entered into meta-regression analyses. The two co-primary outcomes were the relationship between cumulative exposure to ARBs and risk of all cancers combined and the relationship between cumulative exposure and risk of lung cancer. A total of 74,021 patients were randomized to an ARB resulting in a total cumulative exposure of 172,389 person-years of exposure to daily high dose (or equivalent). 61,197 patients were randomized to control. There was a highly significant correlation between the degree of cumulative exposure to ARBs and risk of all cancers combined (slope = 0.07 [95% CI 0.03 to 0.11], p<0.001), and also lung cancer (slope = 0.16 [95% CI 0.05 to 0.27], p = 0.003). Accordingly, in trials where the cumulative exposure was greater than 3 years of exposure to daily high dose, there was a statistically significant increase in risk of all cancers combined (I2 = 31.4%, RR 1.11 [95% CI 1.03 to 1.19], p = 0.006). There was a statistically significant increase in risk of lung cancers in trials where the cumulative exposure was greater than 2.5 years (I2 = 0%, RR 1.21 [95% CI 1.02 to 1.44], p = 0.03). In trials with lower cumulative exposure to ARBs, there was no increased risk of all cancers combined or lung cancer. Cumulative exposure-risk relationship with ARBs was independent of background angiotensin-converting enzyme inhibitor treatment or the type of control (i.e. placebo or non-placebo control). Since this is a trial-level analysis. the effects of patient characteristics such as age and smoking status could not be examined due to lack of patient-level data. In conclusion, this analysis, for the first time, reveals that risk of cancer with ARBs (and specifically lung cancer) increases with increasing cumulative exposure to these drugs. The excess risk of cancer with long-term ARB use has public health implications.

Impact of Angiotensin II Receptor Blockers on Clinical Outcomes after Percutaneous Coronary Intervention in Patients with Acute Myocardial Infarction Based on Data from the Korean National Health Insurance Database (2005-2014)

Background and Objectives

The effectiveness of angiotensin II receptor blockers (ARBs) compared with angiotensin converting enzyme inhibitors (ACEIs) in patients with acute myocardial infarction (AMI) has not been established. We investigated the effects of ARBs on clinical outcomes after percutaneous coronary intervention (PCI) in AMI patients.

Methods

Patients receiving ACEIs or ARBs after AMI treated with PCI between January 2005 and December 2014 were selected from the Korean National Health Insurance Service database. The primary endpoint was major cardiovascular adverse event (MACE; all-cause death, myocardial infarct [MI], or stroke).

Results

We included patients regularly taking ACEIs (n=22,331) or ARBs (n=28,533) (medication possession ratio ≥80%). Compared with the ACEI group, the ARB group contained more females (31% vs. 18%), were older (mean, 63 vs. 60 years), and had more comorbidities, including hypertension (62.8% vs. 44.8%), diabetes (33.9% vs. 26.4%), congestive heart failure (7.9% vs. 4.3%), chronic obstructive pulmonary disease (25.5% vs. 18.9%), and end-stage renal disease (1.3% vs. 0.4%) (p<0.001 for all). After propensity score–matching, ARBs were associated with a 23% lower risk of MACE (hazard ratio [HR], 0.774; 95% confidence interval [CI], 0.715–0.838; p<0.001) than ACEIs. ARB use was also associated with a significantly reduced risk of death (HR, 0.741; 95% CI, 0.659–0.834; p<0.001), MI (HR, 0.731; 95% CI, 0.638–0.837; p<0.001), and revascularization (HR, 0.816; 95% CI, 0.773–0.861; p<0.001).

Conclusions

ARB use was associated with a lower risk of MACE, MI, and revascularization than ACEIs in our retrospective analysis of AMI patients who underwent PCI.

[The effect of amlodipine, bisoprolol on the myocardial ultrastructure of the hypertensive rats]

Calcium channel blockers and beta1-adrenoblockers are effective antihypertensive agents, but their cell protective properties are not investigated well. Spontaneously hypertensive rats received a 10 mg/kg/day amlodipine dose and 25 mg/kg/day bisoprolol dose via an orogastric tube during three months. We performed examination of the myocardium's fragments under a scanning electron microscope. Morphometric investigation of mitochondrions we performed using special program what is named "ORGANELLE". Amlodipine significantly normalizes the ultrastructure of the myocardium. This antihypertensive drug prevented the signs of over-contractility of myofibrils. Amlodipine causes the fusion mitochondrions which has compensatory character on the background of good safety of mitochondrial ultrastructures. Another feature of amlodipine is a significant increase in the number of capillaries. Bisoprolol significantly reduced over-contractility of the myofibrils, but the signs of dystrophic-destructive processes in myofibrils and mitochondrions of cardiomyocytes remained. Bisoprolol improved the condition of the endothelial cells, but the activation of the functional activity of these cells has not been observed. The combined use of two antihypertensive drugs amlodipine and bisoprolol led to a better recovery of myofibrils than their separate use, whereas the effect on mitochondrions noted similar as in the group of rats received bisoprolol and that effect was worse than during amlodipine's monotherapy. Also we didn't reveal a reason to combine these drugs after analysis of the effect of the drug combination on the conditions of blood microvessels, which number was increased compared with hypertensive rats, but significantly less than when rats received only amlodipine. These essential cell-protective effects of amlodipine and bisoprolol in spontaneously hypertensive rats could be a significant additional factor in the treatment of hypertension complicated with pathological changes in the heart.