Dual Blockade of the Renin-Angiotensin System for Cardiorenal Protection: An Update

Absolute and Relative Risks of Kidney and Urological Complications in Patients With Inflammatory Bowel Disease

INTRODUCTION

The burden of kidney and urological complications in patients with inflammatory bowel disease (IBD) remains poorly characterized.

METHODS

We analyzed association between developing IBD (as a time-varying exposure) and relative risks of receiving diagnoses of chronic kidney disease (CKD), acute kidney injury (AKI), or kidney stones, and experiencing a clinically-relevant decline in estimated glomerular filtration rate (eGFR) (CKD progression; composite of kidney failure or an eGFR decline ≥30%) in 1,682,795 individuals seeking healthcare in Stockholm, Sweden, during 2006-2018. We quantified 5- and 10-year absolute risks of these complications in a parallel matched cohort of IBD cases and random controls matched (1:5) on sex, age, and eGFR.

RESULTS

During median 9 years, 10,117 participants developed IBD. Incident IBD was associated with higher risks of kidney-related complications compared with non-IBD periods: hazard ratio (HR) (95% confidence interval) was 1.24 (1.10-1.40) for receiving a CKD diagnosis and 1.11 (1.00-1.24) for CKD progression. For absolute risks, 11.8% IBD cases had a CKD event within 10-year. Of these, 6.4% received a CKD diagnosis, and 7.9% reached CKD progression. The risks of AKI (HR 1.97 [1.70-2.29]; 10-year absolute risk 3.6%) and kidney stones (HR 1.69 [1.48-1.93]; 10-year absolute risk 5.6%) were also elevated. Risks were similar in Crohn's disease and ulcerative colitis.

DISCUSSION

More than 10% of patients with IBD developed CKD within 10-year from diagnosis, with many not being identified through diagnostic codes. This, together with their elevated AKI and kidney stone risks, highlights the need of established protocols for kidney function monitoring and referral to nephrological/urological care for patients with IBD.

Influence of Renal Insufficiency on the Prescription of Evidence-Based Medicines in Patients With Coronary Artery Disease and Its Prognostic Significance: A Retrospective Cohort Study

The purpose of this study was to discuss the present situation of discharge medications in coronary artery disease (CAD) patients with different levels of renal function and assess the potential impact of these medications on the prognosis of this patient population.A retrospective cohort study was conducted. From July 2008 to Jan 2012, consecutive patients with CAD confirmed by coronary angiography of West China Hospital were enrolled and were grouped into 3 estimated glomerular filtration rate (eGFR) categories: ≥60, 30 to 60, and <30 mL/min/1.73 m. The endpoints were all-cause mortality and cardiac mortality.There are 3002 patients according to the inclusion criteria and follow-up requirement. The mean follow-up time was 29.1 ± 12.5 months. CAD patients with worse renal function included more cardiovascular risk factors (advanced age, history of hypertension or diabetes, and diagnosis of acute myocardial infarction). The cumulative survival curves of the patients according to renal function showed that the eGFR <30 mL/min and 30 mL/min ≤ eGFR <60 mL/min groups had a significantly higher risk of all-cause death and cardiovascular death than the group with an eGFR ≥60 mL/min. The prescription of evidence-based medicines (EBMs) at discharge (antiplatelet agents, beta-blockers, statins, and angiotensin-converting enzyme inhibitors [ACEIs] or angiotensin-receptor blockers [ARBs]) was a factor in reducing the risk of all-cause death and cardiovascular death. However, EBMs prescribed at discharge revealed an obvious underuse in renal insufficiency (RI) patients. The results of Cox regression showed that irrespective of the eGFR level, greater use of EBMs resulted in a greater reduction in the risk of all-cause death and cardiovascular death.A higher percentage of patients with CAD and concomitant RI suffered from cardiovascular disease (CVD) risk factors, whereas a lower percentage of these patients used EBMs to prevent CVD events. Strict use of EBMs, including beta-blockers, statins, and ACEIs or ARBs, can lead to more clinical benefits, even for patients with CAD and concomitant RI. Thus, treatment of this patient population with EBMs should be stressed.

To RAS or not to RAS? The evidence for and cautions with renin-angiotensin system inhibition in patients with diabetic kidney disease

Substantial morbidity, mortality, and costs are associated with progressive diabetic kidney disease (DKD). A goal of Healthy People 2020 is to reduce kidney disease attributable to diabetes mellitus and increase the proportion of patients who receive agents that interrupt the renin-angiotensin system (RAS), such as angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs). The mechanisms that contribute to progressive loss of kidney function in patients with diabetes are disrupted by inhibition of the RAS. ACEIs, ARBs and direct renin inhibitors (DRIs) all reduce the effect of angiotensin II, yet each works through a different mechanism and displays properties that may or may not be replicated by the others. As single agents, RAS inhibitors and blockers have been shown to slow the rate of progression of DKD and to reduce new cases of end-stage renal disease in various subsets of patients with diabetes and proteinuria (e.g., albuminuria). However, even with contemporary use of ACEIs, ARBs, and, more recently, DRIs, the burden of kidney disease remains high. Thus investigators sought to explore the utility of combining agents (e.g., dual RAS therapy) in various regimens for cardiovascular and kidney end points. Recent data from the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial (ONTARGET) and Aliskiren Trial in Type 2 Diabetes Using Cardio-Renal Endpoints (ALTITUDE) studies suggest that kidney-related outcomes (composite of dialysis initiation, doubling serum creatinine concentration, or death) were increased with ACEI plus ARB or DRI plus ARB combinations. Consequently, dual therapy should not be routinely prescribed in patients with diabetes until further data become available from other future studies. This review provides an introduction to DKD and a rationale for using RAS inhibition; discusses screening, detection, and monitoring of patients with DKD; and summarizes results from meta-analyses and critical reviews and from recent large randomized controlled studies published since the meta-analyses or reviews. Finally, we suggest a clinical approach for using RAS agents in patients with DKD.

Chronic kidney disease

Chronic kidney disease is a general term for heterogeneous disorders affecting kidney structure and function. The 2002 guidelines for definition and classification of this disease represented an important shift towards its recognition as a worldwide public health problem that should be managed in its early stages by general internists. Disease and management are classified according to stages of disease severity, which are assessed from glomerular filtration rate (GFR) and albuminuria, and clinical diagnosis (cause and pathology). Chronic kidney disease can be detected with routine laboratory tests, and some treatments can prevent development and slow disease progression, reduce complications of decreased GFR and risk of cardiovascular disease, and improve survival and quality of life. In this Seminar we discuss disease burden, recommendations for assessment and management, and future challenges. We emphasise clinical practice guidelines, clinical trials, and areas of uncertainty.

Management of patients with chronic kidney disease

Chronic kidney disease (CKD) is a silent disease which worsens gradually to end-stage kidney disease (ESKD). US kidney disease outcomes quality initiative (KDOQI) guidelines indicate five stages of CKD based on the severity of kidney function which is assessed by estimating the glomerular filtration rate (GFR) by the modification of diet in renal disease (MDRD) formula. The management of CKD patients with mild renal damage (stage 1-2 KDOQI) is articulated on the reduction of proteinuria (<500 mg/day), reduction of sitting systolic and diastolic blood pressure (<130/80 mmHg), salt restriction diet, diuretics (furosemide, spironolactone), antihypertensive agents (ACE inhibitors or ARBs (angiotensin II receptor blockers) or both as first-line therapy), additional other antihypertensives (aliskiren, non-dihydropyridine calcium channel blockers, beta blockers), body weight reduction, cigarette smoking stopping, allopurinol therapy and non-use of some drugs (non-steroidal anti-inflammatory agents, acetaminophen, bisphosphonates, oral estrogens) and herbals. The management of CKD patients with moderate-severe renal damage (stage 3-5 KDOQI) is based on the above recommendations plus low protein diet, correction of hyperkalaemia, metabolic acidosis, and administration of vitamin D derivates and erythropoietin for the correction of mineral metabolism disorders and anemia, respectively. In conclusion, patients with CKD (stage 1-2 KDOQI) may be correctly managed by primary care physicians, individuals in stage 3-5 KDOQI need the supervision of nephrologists to assess those patients who progress to ESKD and require renal replacement therapy.

Cardiorenal syndrome: an unsolved clinical problem

The clinical relevance of the bidirectional cross-talk between heart and kidney is increasingly recognized. However, the optimal approach to the management of kidney dysfunction in heart failure remains unclear. The purpose of this article is to outline the most plausible pathophysiologic theories that attempt to explain the renal impairment in acute and chronic heart failure, and to review the current treatment strategies for these situations.

Hypertension in patients with chronic kidney disease

Hypertension is very common in patients with chronic kidney disease (CKD); it causes early loss of kidney function and accelerated cardiovascular morbidity and mortality. African American patients with hypertension and genetic disposition are at an even higher risk for renal disease and ultimately renal failure. Hypertensive patients with CKD should aim for stringent blood pressure (BP) control (target < 130/80 mm Hg) requiring more than one drug with renin-angiotensin-aldosterone system blockade as a component of therapy targeting both hyper-tension and proteinuria. Management of hypertension in the dialysis population should focus on ambulatory measurements of BP and the use of longer-acting antihypertensive drugs, with their dosage and timing adjusted according to their dialytic clearances. Hypertension is also common among kidney transplant recipients and contributes to graft loss and premature death. The target BP in transplant recipients is the same as in the CKD population, with no preference for one drug group over another. Unless contraindicated, angiotensin-converting enzyme inhibitors remain the drugs of choice for hypertension in patients with autosomal-dominant polycystic kidney disease, in whom diastolic cardiac dysfunction is a prominent feature.

Blocking the RAAS at different levels: an update on the use of the direct renin inhibitors alone and in combination

The renin–angiotensin–aldosterone system (RAAS), an important regulator of blood pressure and mediator of hypertension-related complications, is a prime target for cardiovascular drug therapy. Angiotensin-converting enzyme inhibitors (ACEIs) were the first drugs to be used to block the RAAS. Angiotensin II receptor blockers (ARBs) have also been shown to be equally effective for treatment. Although these drugs are highly effective and are widely used in the management of hypertension, current treatment regimens with ACEIs and ARBs are unable to completely suppress the RAAS. Combinations of ACEIs and ARBs have been shown to be superior than to either agent alone for some, but certainly not all, composite cardiovascular and kidney outcomes, but dual RAAS blockade with the combination of an ACEI and an ARB is sometimes associated with an increase in the risk for adverse events, primarily hyperkalemia and worsening renal function. The recent introduction of the direct renin inhibitor, aliskiren, has made available new combination strategies to obtain a more complete blockade of the RAAS with fewer adverse events. Renin system blockade with aliskiren and another RAAS agent has been, and still is, the subject of many large-scale clinical trials and furthermore, is already available in some countries as a fixed combination.

Addressing the theoretical and clinical advantages of combination therapy with inhibitors of the renin-angiotensin-aldosterone system: antihypertensive effects and benefits beyond BP control

AIMS

This article reviews the importance of the renin-angiotensin-aldosterone system (RAAS) in the cardiometabolic continuum; presents the pros and cons of dual RAAS blockade with angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs); and examines the theoretical and practical benefits supporting the use of direct renin inhibitors (DRIs) in combination with ACEIs or ARBs.

MAIN METHODS

The author reviewed the literature for key publications related to the biochemical physiology of the RAAS and the pharmacodynamic effects of ACEIs, ARBs, and DRIs, with a particular focus on dual RAAS blockade with these drug classes.

KEY FINDINGS

Although ACEI/ARB combination therapy produces modest improvement in BP, it has not resulted in the major improvements predicted given the importance of the RAAS across the cardiorenal disease continuum. This may reflect the fact that RAAS blockade with ACEIs and/or ARBs leads to exacerbated renin release through loss of negative-feedback inhibition, as well as ACE/aldosterone escape through RAAS and non-RAAS-mediated mechanisms. Plasma renin activity (PRA) is an independent predictor of morbidity and mortality, even for patients receiving ACEIs and ARBs. When used alone or in combination with ACEIs and ARBs, the DRI aliskiren effectively reduces PRA. Reductions in BP are greater with these combinations, relative to the individual components alone.

SIGNIFICANCE

It is possible that aliskiren plus either an ACEI or ARB may provide greater RAAS blockade than monotherapy with ACEIs or ARBs, and lead to additive improvement in BP and clinically important outcomes.

Feasibility of combined treatment with enalapril and candesartan in advanced chronic kidney disease

BACKGROUND

Dual blockade of the renin-angiotensin system (RAS) has been claimed to have a specific renal protective effect in chronic kidney disease (CKD). The present short-term study reports on the feasibility of dual blockade in a consecutive group of patients with CKD stage 3-5.

METHODS

Forty-seven CKD patients, mean age 59 years, with mean estimated glomerular filtration rate (GFR) 26 ml/min/1.73 m(2) (range 13-49) and blood pressure (BP) 133/78 mmHg, were block randomized in an open study to 16 weeks of monotherapy with increasing doses of RAS blockade aiming at enalapril 20 mg o.d. or candesartan 16 mg o.d. Thereafter, the complementary drug was added in incremental doses over a period of 5 weeks aiming at combined enalapril 20 mg and candesartan 16 mg for 3 weeks. Seventy-five percent of the patients were known to be RAS blockade tolerant. Blood samples and BP were measured every 2-3 weeks. Doses of study medication were reduced in case of hyperkalemia >5.5 mmol/l, a sustained rise in p-creatinine >30% or symptomatic hypotension.

RESULTS

Twenty-one patients (45%) did not tolerate dual blockade in aimed dosages due to unacceptable p-creatinine increase (n = 12, including two study withdrawals), hypotension (n = 6), general discomfort (n = 2) or unmanageable hyperkalemia (n = 1). Hyperkalemia >5.5 mmol/l was seen in seven patients (15%). The reduced-dose group had baseline lower eGFR and diastolic BP.

CONCLUSIONS

Forty-five percent of CKD stage 3-5 patients did not tolerate dual RAS blockade with 20 mg enalapril and 16 mg candesartan daily, primarily due to loss of renal function or hypotension. Hyperkalemia could be managed in most patients. Caution is recommended when giving this treatment to patients with advanced CKD.

Clinical approach in treatment of resistant hypertension

Resistant hypertension, defined as failure to achieve target blood pressure despite the use of optimal or maximum doses of at least 3 agents, one of which is a diuretic, or requiring 4 or more medications to achieve blood pressure goal, is likely to affect up to 20% of all patients with hypertension. Apparent resistant hypertension may be caused by medication nonadherence, substances that either interfere with antihypertensive mediations or cause blood pressure elevation, and under- or inappropriate medication treatment. Certain patient characteristics are associated with the presence of resistant hypertension and include chronic kidney disease, diabetes, obesity, and presence of end-organ damage (microalbuminuria, retinopathy, left-ventricular hypertrophy). Secondary causes of resistant hypertension are not uncommon and include obstructive sleep apnea, chronic kidney disease, primary aldosteronism, renal artery stenosis, pheochromocytoma, and Cushing's disease. Initial medication management usually includes adding or increasing the dose of a diuretic, which is effective in lowering the blood pressure of a large number of patients with resistant hypertension. Additional management options include maximizing lifestyle modification, combination therapy of antihypertensive agents depending on individual patient characteristics, adding less-commonly used fourth- or fifth-line antihypertensive agents, and referral to a hypertension specialist.

The biochemical pharmacology of renin inhibitors: implications for translational medicine in hypertension, diabetic nephropathy and heart failure: expectations and reality

The renin-angiotensin-aldosterone system (RAAS) plays a dominant role in the pathophysiology of hypertension, Diabetes mellitus (DM), chronic kidney disease (CKD) and chronic heart failure (CHF). Therefore, drugs that block key components of the RAAS such as ACE inhibitors (ACEi) and angiotensin receptor blockers (ARBs) have gained wide clinical use for these indications. Despite progress, the morbidity and mortality of patients treated with ACEi or ARBs remain high. Small molecules that directly inhibit renin (DRI) and are orally active have also been developed and one such drug, aliskiren, was introduced into clinical use for treatment of hypertension in 2007. Further clinical trials aimed to expand the therapeutic use of aliskiren are in progress for CKD-DM and CHF. In this review we analyze and review the translational medicine prospects of aliskiren in respect to the biochemical pharmacology of the RAAS, the marketed RAAS modulators and the new emerging science regarding the role of prorenin, renin and renin receptors in cardiovascular biology and disease. The information already gained with aliskiren, raises questions regarding the advantages of DRIs as monotherapy compared to marketed ACEis and ARBs, their potential added value in combination with other RAAS modulators and other unproven benefits in relation to prorenin and renin receptor biology. This review will also indicate basic and clinical research needs that are critical to determine whether DRIs can provide meaningful added medical benefits over contemporary medicines that regulate the RAAS, and the need to identify patients that are more likely to benefit from DRIs and any possible long term adverse effects.