Cardiac protection: evolving role of angiotensin receptor blockers

Thyroid-stimulating hormone and adverse left ventricular remodeling following ST-segment elevation myocardial infarction

BACKGROUND

Adverse left ventricular remodeling is one of the major determinants of heart failure and mortality in patients surviving ST-segment elevation myocardial infarction (STEMI). The hypothalamic-pituitary-thyroid axis is a key cardiovascular regulator; however, the relationship between hypothalamic-pituitary-thyroid status and post-STEMI left ventricular remodeling is unclear. We aimed to investigate the association between thyroid-stimulating hormone concentrations and the development of left ventricular remodeling following reperfused STEMI.

METHODS

In this prospective observational study of 102 consecutive STEMI patients, thyroid-stimulating hormone levels were measured at the first day after infarction and 4 months thereafter. Cardiac magnetic resonance scans were performed within the first week as well as at 4 months follow-up to determine infarct characteristics, myocardial function and as primary endpoint left ventricular remodeling, defined as a 20% or greater increase in left ventricular end-diastolic volume.

RESULTS

Patients with left ventricular remodeling (n=15, 15%) showed significantly lower concentrations of baseline (1.20 [0.92-1.91] vs. 1.73 [1.30-2.60] mU/l; P=0.02) and follow-up (1.11 [0.86-1.28] vs. 1.51 [1.15-2.02] mU/l; P=0.002) thyroid-stimulating hormone. The association between baseline thyroid-stimulating hormone and left ventricular remodeling remained significant after adjustment for major clinical (peak high-sensitivity cardiac troponin T and C-reactive protein, heart rate; odds ratio (OR) 5.33, 95% confidence interval (CI) 1.52-18.63; P=0.01) and cardiac magnetic resonance predictors of left ventricular remodeling (infarct size, microvascular obstruction, ejection fraction; OR 4.59, 95% CI 1.36-15.55; P=0.01). Furthermore, chronic thyroid-stimulating hormone was related to left ventricular remodeling independently of chronic left ventricular remodeling correlates (infarct size, ejection fraction, left ventricular end-diastolic volume, left ventricular end-systolic volume; OR 9.22, 95% CI 1.69-50.22; P=0.01).

CONCLUSIONS

Baseline and chronic thyroid-stimulating hormone concentrations following STEMI were independently associated with left ventricular remodeling, proposing a novel pathophysiological axis in the development of post-STEMI left ventricular remodeling.

Drug Interactions in Parkinson's Disease: Safety of Pharmacotherapy for Arterial Hypertension

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative disorder of the central nervous system, observed in patients aged older than 50 years. In this study, we review interactions between therapies used in PD and selected antihypertensive agents. Moreover, in view of the lack of evidence-based recommendations regarding the pharmacotherapy of arterial hypertension in PD patients, we propose effective and safe therapeutic algorithms for these two coexisting conditions.

METHOD

We used the "Drug interactions" database affiliated with the Ministry of Health, which allows for the identification of interactions between compared active compounds. The database is updated on a monthly basis and all data are consistent with current legislation. For information about interactions, we additionally added data from the British National Formulary, a joint publication of the British Medical Association and the Royal Pharmaceutical Society of Great Britain. In this analysis, we also used data from Micromedex^®, Cerner Multum™, Wolters Kluwer™, Lexicomp^® and Stockley's^®. We analysed the potential interactions between antihypertensive and anti-parkinsonian agents included in respective guidelines on the pharmacotherapy of these conditions.

RESULTS

Our analysis revealed the lack of clinically relevant interactions between preparations of levodopa and benserazide (used for the treatment of PD) and angiotensin-converting enzyme inhibitors, antagonists of AT₁ receptor for angiotensin II or antagonists of β-adrenoreceptors (β-adrenolytics).

CONCLUSION

To avoid major drug-to-drug interactions, patients receiving preparations of levodopa and benserazide should be prescribed angiotensin-converting enzyme inhibitors, antagonists of AT₁ receptor for angiotensin II, or antagonists of β-adrenoreceptors (β-adrenolytics) as the first-line agents of antihypertensive treatment.

Prediabetes: grounds of pitfall signalling alteration for cardiovascular disease

Prediabetes manifested by impaired glucose tolerance and impaired fasting glucose offers high risk of myocardial dysfunction by causing endothelial dysfunction, inflammation, oxidative stress, atherosclerosis and genetic alterations.

The prince and the pauper. A tale of anticancer targeted agents

Cancer rates are set to increase at an alarming rate, from 10 million new cases globally in 2000 to 15 million in 2020. Regarding the pharmacological treatment of cancer, we currently are in the interphase of two treatment eras. The so-called pregenomic therapy which names the traditional cancer drugs, mainly cytotoxic drug types, and post-genomic era-type drugs referring to rationally-based designed. Although there are successful examples of this newer drug discovery approach, most target-specific agents only provide small gains in symptom control and/or survival, whereas others have consistently failed in the clinical testing. There is however, a characteristic shared by these agents: -their high cost-. This is expected as drug discovery and development is generally carried out within the commercial rather than the academic realm. Given the extraordinarily high therapeutic drug discovery-associated costs and risks, it is highly unlikely that any single public-sector research group will see a novel chemical "probe" become a "drug". An alternative drug development strategy is the exploitation of established drugs that have already been approved for treatment of non-cancerous diseases and whose cancer target has already been discovered. This strategy is also denominated drug repositioning, drug repurposing, or indication switch. Although traditionally development of these drugs was unlikely to be pursued by Big Pharma due to their limited commercial value, biopharmaceutical companies attempting to increase productivity at present are pursuing drug repositioning. More and more companies are scanning the existing pharmacopoeia for repositioning candidates, and the number of repositioning success stories is increasing. Here we provide noteworthy examples of known drugs whose potential anticancer activities have been highlighted, to encourage further research on these known drugs as a means to foster their translation into clinical trials utilizing the more limited public-sector resources. If these drug types eventually result in being effective, it follows that they could be much more affordable for patients with cancer; therefore, their contribution in terms of reducing cancer mortality at the global level would be greater.

Pathogenesis of chronic heart failure: change of dominating paradigm

The review considers literature data reflecting the evolution of views on pathogenesis of chronic heart failure. Connection of revision of a dominating paradigm of pathogenesis at every stage of development of cardiology with changes in approaches to therapy of chronic heart failure is analyzed.

The tissue renin-angiotensin system and intracellular signalling

PURPOSE OF REVIEW

The renin-angiotensin system is not what it was, or for that matter not necessarily where we thought it should be. For example, there is a novel angiotensin I-metabolizing enzyme that generates angiotensin 1-7 rather than angiotensin II. Moreover, we are slowly realizing the importance of local rather than circulating angiotensin II.

RECENT FINDINGS

Rather than concentrating on the systemic renin-angiotensin system, recent work has concentrated on elucidating the consequences of increasing angiotensin II production within specific organs, such as the heart and vasculature, as well as in the pancreas and in adipose tissue. Inhibition of angiotensin II production either using angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers not only reverses remodelling but also increases tissue insulin sensitivity. Targeting the renin-angiotensin system clinically delays the onset of type 2 diabetes, but the mechanisms involved are not clearly understood. Moreover, at least one other angiotensin-converting enzyme homologue (ACE2) plays a significant role in the regulation of heart and kidney function, and as it generates angiotensin 1-7 from angiotensin I, it is proposed to counteract the detrimental effects associated with the activation of the classic renin-angiotensin system.

SUMMARY

There is a need to re-evaluate the role(s) played by the molecular components of the "extended" local renin-angiotensin system and their role in vascular disease and type 2 diabetes.

Left ventricular dysfunction in hypertensive patients with Type 2 diabetes mellitus

AIMS

To characterize left ventricular function in hypertensive patients with Type 2 diabetes and normal ejection fraction, and to relate these findings to pathogenic factors and clinical risk markers.

METHODS

We examined 70 hypertensive patients with Type 2 diabetes mellitus with ejection fraction > 0.55 and fractional shortening > 0.25, all without any cardiac symptoms. Thirty-five non-diabetic subjects served as control subjects. Left ventricular longitudinal function was examined by tissue Doppler derived myocardial strain rate and peak systolic velocities.

RESULTS

Hypertensive patients with diabetes had a significantly higher systolic strain rate (-1.1 +/- 0.3 s(-1) vs. -1.6 +/- 0.3 s(-1), P < 0.001) and lower systolic peak velocities (3.3 +/- 1.0 vs. 5.6 +/- 1.0 cm/s, P < 0.001) compared with control subjects. Myocardial systolic strain rate correlated significantly to left ventricular mass (r = 0.40, P < 0.01) and to both HbA1c (r = 0.43, P < 0.01), and fructosamine (r = 0.40, P < 0.01), but was not related to serum levels of carboxymethyllysine, albuminuria, blood pressure (dipping/non-dipping), or oral hypoglycaemic therapy. Patients with diastolic dysfunction had significantly higher levels of urine albumin [21.0 (5-2500) mg/l, vs. 9.5 (1-360), P < 0.01], heart rate (78 +/- 13 vs. 67 +/- 10 b.p.m., P < 0.005), and seated diastolic blood pressure (85 +/- 6 vs. 81 +/- 7 mmHg, P < 0.05) and non-dipping diastolic blood pressure was more frequent.

CONCLUSIONS

Long axis left ventricular systolic function was significantly decreased in hypertensive patients with Type 2 diabetes mellitus, and is associated with hyperglycaemia and left ventricular hypertrophy. Diastolic dysfunction was closely related to increased diastolic blood pressure, non-dipping and increased urinary albumin excretion.

Do ACE inhibitors or angiotensin II antagonists reduce total mortality and arrhythmic mortality? A critical review of controlled clinical trials

ACE-inhibitors (ACE-I) represent effective drugs more and more widely used in acute myocardial infarction (AMI) patients, in post AMI patients and mainly, today, in CHF patients.A complete review of the scientific literature and of all the randomized controlled clinical trials (RCTs), where ACE-I have been tested directly or in association with other drugs, have been performed. ACE-I effects on total mortality (TM) and arrhythmic mortality (AM) and other composite clinical endpoints have been evaluated. It is well known that frequent ventricular arrhythmias (VA) and a high incidence of sudden death (SD) can be documented in CHF patients; nevertheless a direct relationship between VA, TM, and AM has not been clearly demonstrated; neither beneficial effects, on the same endpoints, of the treatment and suppression of ambient VA in CHF. Conversely, sometimes clear negative effects on both TM and AM have been observed. According to individual studies and two recent complete and large metanalysis, ACE-I were unable to reduce AM, but they reduced TM. Furthermore, they can affect and modify many, if not all, of the triggering factors of VA and SD in this context. Differently from ACE-I, betablockers (BB) have been clearly associated with a reduction in TM and AM, in the same context. Thus, at present time, ACE-I, with or without BB, should be considered the standard therapy in all patients with CHF, if not contraindicated. Angiotensin II antagonists (AII-a) probably represent a comparably effective treatment, in all CHF patients and mainly in those patients, suffering from side effects or showing intolerance to ACE-I, but we are still lacking definitive data from RCTs. In many RCTs, conducted with traditional antiarrhythmic drug therapy (ADT), these drugs have been widely used, contributing probably, in a consistent way, to some of the positive results of these studies. All primary and some secondary implantable defibrillators (ICD) RCTs, in the prevention of SD, have included these drugs as the standard treatment of the underlying cardiac disease, with or without CHF. The same therapeutical strategy is regularly applied in all biventricular pacing (BP) RCTs, with or without the ICD. These trials are supposed to assess the reduction in TM and AM, preventing deterioration or progression of CHF and improving the quality of the patients' s life.Finally, according to these clinical evidences, in the last part of the review, we stress the need for a more widespread implementation of ACE-I and AII-a in treating CHF patients.

[New pharmacological agents in heart failure]

Heart failure is a common and growing public health problem, with increasing incidence and prevalence over the last 2 decades. Despite improvements in its current management, heart failure is still associated with significant morbidity and mortality. This has motivated the search for newer therapeutic modalities, which are based on a better understanding on the pathophysiologic events that lead to heart failure. This review summarizes the potential role of new pharmacological agents in the treatment of heart failure. These potential new agents can be classified according to their role in the modulation of the main pathophysiologic abnormalities that characterized heart failure, that include: cellular-extracellular abnormalities, endothelial dysfunction, neurohormonal and immunologic activation.

An angiotensin II type 1 receptor blocker, candesartan, increases myocardial apoptosis in rats with acute ischemia-reperfusion

Angiotensin II (Ang II) and apoptosis contribute significantly to myocardial ischemia-reperfusion (I-R) injury. Evidence indicates that Ang II may activate apoptosis in myocytes. The present study was undertaken to investigate the effects of angiotensin receptor blockers (ARBs), candesartan, on the apoptosis of cardiac myocytes in rats after I-R. Rats were divided into a control group, a candesartan group I (0.015 mg/kg), and a candesartan group II (0.03 mg/kg). Candesartan was intravenously administered 30 min before ischemia. All rats were subjected to 30 min of coronary occlusion followed by 3 h of reperfusion. The data showed that left ventricular (LV) systolic pressure and LV +dp/dt was decreased after administration of candesartan, but increased after reperfusion in the candesartan group II, compared with those in the candesartan group I and control group. LV -dp/dt was decreased after candesartan administration in candesartan group II. The number of apoptotic cells in the candesartan groups (497+/-204 and 543+/-254, respectively) was higher than that in the control group (287+/-166; p<0.05). There was no significant difference in infarct size among the three groups. However, plasma CPK was lower in the candesartan groups than in the control group. Northern blot analysis showed that p53 mRNA was upregulated in the candesartan groups, in association with increased expression of bax mRNA. Immunohistochemical analysis showed that p53 and bax immunoreactivity were increased in both of the candesartan groups. In conclusion, candesartan increased apoptosis in the rat hearts after acute I-R, and this increase was possibly mediated by upregulation of p53 and bax gene expressions. In addition, candesartan was shown to improve LV function, in association with reduction of CPK release.

Suppression of experimental abdominal aortic aneurysms in the rat by treatment with angiotensin-converting enzyme inhibitors

PURPOSE

Pathologic remodeling of the extracellular matrix is a critical mechanism in the development and progression of abdominal aortic aneurysms (AAAs). Although angiotensin-converting enzyme (ACE) inhibitors are known to alter vascular wall remodeling in other conditions, their effects on AAAs are unknown. In this study we assessed the effect of ACE inhibitors in a rodent model of aneurysm development.

METHODS

Male Wistar rats underwent transient aortic perfusion with porcine pancreatic elastase, followed by treatment with one of three ACE inhibitors (captopril [CP], lisinopril [LP], or enalapril [EP]), an angiotensin (AT)1 receptor antagonist (losartan [LOS]), or water alone (9 rats in each group). Blood pressure and aortic diameter (AD) were measured before elastase perfusion and on day 14, with an AAA defined as an increase in AD (DeltaAD) of more than 100%. The structural features of the aortic wall were examined by means of light microscopy.

RESULTS

Aneurysmal dilatation consistently developed within 14 days of elastase perfusion in untreated rats, coinciding with the development of a transmural inflammatory response and destruction of the elastic media (mean DeltaAD, 223% +/- 28%). All three ACE inhibitors prevented AAA development (mean DeltaAD: CP, 67% +/- 4%; LP, 18% +/- 12%; and EP, 14% +/- 3%; each P <.05 vs controls). ACE inhibitors also attenuated the degradation of medial elastin without diminishing the inflammatory response. Surprisingly, the aneurysm-suppressing effects of ACE inhibitors were dissociated from their effects on systemic hemodynamics, and LOS had no significant effect on aneurysm development compared with untreated controls (mean DeltaAD, 186% +/- 19%).

CONCLUSION

Treatment with ACE inhibitors suppresses the development of elastase-induced AAAs in the rat. Although this is associated with the preservation of medial elastin, the mechanisms underlying these effects appear to be distinct from hemodynamic alterations alone or events mediated solely by AT1 receptors. Further studies are needed to elucidate how ACE inhibitors influence aortic wall matrix remodeling during aneurysmal degeneration.

Combined therapy with an angiotensin II receptor blocker and an angiotensin-converting enzyme inhibitor in heart failure

OBJECTIVE

To evaluate the safety, tolerability, and efficacy of chronic combination therapy with an angiotensin-converting enzyme (ACE) inhibitor and an angiotensin II receptor blocker (ARB) in the management of heart failure.

DATA SOURCES

Clinical literature was accessed through MEDLINE (January 1966-June 2000). Key search terms included angiotensin-converting enzyme inhibitor; losartan; combined modality therapy; drug effects; heart failure, congestive; and receptors, angiotensin.

DATA SYNTHESIS

Heart failure is widely prevalent and continues to be associated with high morbidity and mortality, even with currently recommended care. At the moderate doses studied for patients with mild heart failure in brief trials, combined ACE inhibitor and ARB therapy was well tolerated and had an additive effect in reducing blood pressure and relieving symptoms of heart failure.

CONCLUSIONS

An ARB combined with an ACE inhibitor may benefit heart failure patients who are receiving all other recommended therapies. Further trials are needed to evaluate long-term safety effectiveness, quality of life, and survival before the combination can be recommended for routine use.

Update on recent clinical trials in congestive heart failure

Understanding of the pathophysiology of heart failure has advanced over the last decade, resulting in new therapeutic advances. Convincing data exist that angiotensin-converting enzyme (ACE) inhibition and adrenergic blockade are the most important therapies and have the capacity to improve survival and lower morbidity. Higher doses of both ACE inhibitors and beta-blockers appear to provide additional benefits. The aldosterone antagonist spironolactone, when used in severe heart failure, provides additional survival advantage when added to standard triple therapy. Angiotensin receptor blockers have not been shown to be superior to ACE inhibitors, and their role in heart failure treatment requires further investigation. No trial's data support the use of inotropic agents or calcium channel blockers in heart failure. A number of new therapeutic agents, including vasopressin antagonists and tumor necrosis factor-alpha receptor antibody are in phase II and III clinical trials. If proved beneficial, they may provide new treatment options for patients with heart failure. Nevertheless, the current challenge is to increase the use of proven therapies, namely ACE inhibitors and beta-blockers, to improve outcomes in the rapidly growing population of patients with congestive heart failure.