Evidence that Statins Protect Renal Function During Endovascular Repair of AAAs

NAD+ Biosynthesis Impairment and Acute Kidney Injury after Major Vascular Surgery

Acute kidney injury (AKI) is a serious complication after vascular surgery. Reduced synthesis of nicotinamide adenine dinucleotide (NAD+) from tryptophan is associated with an increased risk of AKI in critically ill patients, patients hospitalized with COVID-19, and cardiac surgery patients, and is marked by elevated urinary quinolinate and quinolinate to tryptophan ratios. We measured quinolinate concentrations in vascular surgery patients to determine if impaired NAD+ synthesis was associated with AKI in this patient population. Eight preoperative and eight postoperative vascular surgery patients who developed AKI were selected from a parent study to participate in this single-center case-control study. They were matched with controls who did not develop AKI based on age, sex, BMI, eGFR, hypertension, and diabetes. Urinary quinolinate and tryptophan concentrations were measured at anesthetic induction and on postoperative day one. Two-sided Mann-Whitney U tests were used to compare quinolinate and quinolinate to tryptophan ratios. Multivariate linear regression modeling was used to estimate the relationship between quinolinate and serum creatinine. There was no difference in preoperative or postoperative urine quinolinate concentrations or the preoperative quinolinate to tryptophan ratio between patients that did and did not develop AKI (p = 0.07, 0.50, and 0.32, respectively). However, postoperative quinolinate to tryptophan ratios were higher in AKI patients (p = 0.04). Further, after adjustment for AKI risk factors, higher preoperative quinolinate concentrations and higher postoperative quinolinate to tryptophan ratios were associated with greater postoperative creatinine increases (p = 0.04 and 0.04, respectively). These data suggest that impaired NAD+ synthesis may contribute to AKI development in vascular surgery patients.

Renal Dysfunction Following Elective Endovascular Aortic Aneurysm Repair

Abdominal aortic aneurysm (AAA) is a degenerative disease of the aortic wall with potentially fatal complications. Open repair (OR) was considered the gold standard, until the emergence of endovascular aneurysm repair (EVAR), which is less invasive and equally (if not more) effective. As the popularity of endovascular procedures grows, related complications become more evident, with kidney damage being one of them. Although acute kidney injury (AKI) following EVAR is relatively common, its true incidence is still uncertain. Also, there is insufficient data concerning long-term renal outcomes after EVAR, especially with repeated contrast agent exposure. Despite the lack of firm evidence on the effectiveness of individual strategies, it is evident that prevention of AKI following EVAR requires a multifactorial approach. This review focuses on recent findings based on human studies regarding the current evidence of renal impairment after EVAR, its quantification and strategies for its prevention.

Effects of chronic statin use on 30-day major adverse cardiac and cerebrovascular events after thoracic endovascular aortic repair

BACKGROUND

Cardiac and cerebrovascular complications are major causes of adverse outcomes following thoracic endovascular aortic repair (TEVAR). The benefits of statins have been established, but little is known about their impact on patients undergoing TEVAR. We investigated whether chronic statin use protected against early postoperative major adverse cardiac and cerebrovascular events (MACCEs) after TEVAR.

METHODS

We retrospectively reviewed 211 patients who underwent TEVAR between February 2013 and March 2017 classified into two groups, those with acute aortic syndrome (AAS, N.=79) and those without (non-AAS, N.=132). Patients were subdivided according to preoperative statin therapy for ≥3 months or not. The primary endpoint was 30-day MACCE, defined as myocardial infarction, stroke, arrhythmia, cardiovascular death, or cerebrovascular death. Acute kidney injury (AKI) occurrence within 48 hours was also evaluated. Multivariate logistic regression analysis was performed to identify independent risk factors for MACCEs and AKI.

RESULTS

Incidence of MACCEs (1% vs. 11%, P=0.019) was significantly lower in the statin group than in the no-statin group in non-AAS patients. Multivariate logistic regression analysis revealed statin use (odds ratio 0.85, 95% confidence interval 0.01-0.95, P=0.046) as an independent predictor for MACCE in non-AAS patients. The AKI incidence was significantly higher in the statin group than in the no-statin group in AAS patients (44% vs. 15%, P=0.018).

CONCLUSIONS

In patients undergoing TEVAR, chronic statin use was associated with reduced 30-day MACCEs in non-AAS patients, but not in AAS patients. It might rather be associated with increased risk of AKI in AAS patients.

Simvastatin protects ischemic spinal cord injury from cell death and cytotoxicity through decreasing oxidative stress: in vitro primary cultured rat spinal cord model under oxygen and glucose deprivation-reoxygenation conditions

Background

Ischemia and the following reperfusion damage are critical mechanisms of spinal cord injury. Statins have been reported to decrease ischemia–reperfusion injury in many organs including the spinal cord. Anti-oxidative effect is one of the main protective mechanisms of statin against neuronal death and cytotoxicity. We hypothesized that statins’ anti-oxidative property would yield neuroprotective effects on spinal cord ischemia–reperfusion injury

Methods

Primary cultured spinal cord motor neurons were isolated from Sprague–Dawley rat fetuses. Ischemia–reperfusion injury model was induced by 60 min of oxygen and glucose deprivation (OGD) and 24 h of reoxygenation. Healthy and OGD cells were treated with simvastatin at concentrations of 0.1, 1, and 10 μM for 24 h. Cell viability was assessed using water-soluble tetrazolium salt (WST)-8, cytotoxicity with LDH, and production of free radicals with DCFDA (2′,7′-dichlorofluorescein diacetate).

Results

OGD reduced neuronal viability compared to normoxic control by 35.3%; however, 0.1–10 μM of simvastatin treatment following OGD improved cell survival. OGD increased LDH release up to 214%; however, simvastatin treatment attenuated its cytotoxicity at concentrations of 0.1–10 μM (p < 0.001 and p = 0.001). Simvastatin also reduced deteriorated morphological changes of motor neurons following OGD. Oxidative stress was reduced by simvastatin (0.1–10 μM) compared to untreated cells exposed to OGD (p < 0.001).

Conclusions

Simvastatin effectively reduced spinal cord neuronal death and cytotoxicity against ischemia–reperfusion injury, probably via modification of oxidative stress.

The effect of adding ezetimibe to rosuvastatin on renal function in patients undergoing elective vascular surgery

We compared the effects of lipid lowering with rosuvastatin (RSV) monotherapy versus intensified treatment by combining RSV with ezetimibe (EZT) on kidney function in patients undergoing vascular surgery. Patients were randomly assigned to either 10 mg/d RSV (n = 136) or RSV 10 mg/d plus EZT 10 mg/d (RSV/EZT, n = 126). At 12 months, a similar decrease in estimated glomerular filtration rate (eGFR) was noted. Patients who achieved a low-density lipoprotein cholesterol (LDL-C) of <100 mg/dL had less eGFR decrease than those patients having an LDL-C limit of more than 100 mg/dL. There were no significant changes in the urinary total protein to creatinine ratio in either group. Significant microalbuminuria was evident in both the groups. Patients undergoing vascular surgery show deterioration in their renal function during the first year, despite statin therapy. Intensified lipid-lowering therapy by adding EZT does not appear to have any renoprotective effect.

A systematic review and meta-analysis indicates underreporting of renal dysfunction following endovascular aneurysm repair

Deterioration in renal function has been described after endovascular repair of abdominal aortic aneurysms (EVRs). The etiology is multifactorial and represents an important therapeutic target. A need exists to quantitatively summarize incidence and severity of renal dysfunction after EVR to allow better-informed attempts to preserve renal function and improve life expectancy. Here a systematic search was performed using Medline and Embase for renal function after EVR applying PRISMA statements. Univariate and multivariate random-effects meta-analyses were performed to estimate pooled postoperative changes in serum creatinine and creatinine clearance at four time points after EVR. Clinically relevant deterioration in renal function was also estimated at 1 year or more after EVR. Pooled probability of clinically relevant deterioration in renal function at 1 year or more was 18% (95% confidence interval of 14-23%, I2 of 82.5%). Serum creatinine increased after EVR by 0.05 mg/dl at 30 days/1 month, 0.09 mg/dl at 1 month to 1 year, and 0.11 mg/dl at 1 year or more (all significant). Creatinine clearance decreased after EVR by 5.65 ml/min at 1 month-1 year and by 6.58 ml/min at 1 year or more (both significant). Thus, renal dysfunction after EVR is common and merits attention.

The impact of chronic renal insufficiency on vascular surgery patient outcomes

Renal insufficiency is associated with an increased incidence of poor outcomes, including cardiovascular events and death, in the general population. Renal dysfunction appears to have a particularly negative impact in patients undergoing vascular surgery and endovascular therapy. Although the exact mechanism is unknown, increased levels of inflammatory and biochemical modulators associated with adverse cardiovascular outcomes, as well as endothelial dysfunction, appear to play a role in the association between renal insufficiency and adverse outcomes. Outcomes after the surgical and endovascular treatment of abdominal aortic aneurysms, carotid disease, and peripheral arterial disease are all negatively affected by renal insufficiency. Patients with renal dysfunction may warrant intervention for the treatment of critical limb ischemia and symptomatic carotid stenosis, given the comparatively worse outcomes associated with medical management. Open repair of aortic aneurysms and carotid intervention for asymptomatic disease in patients with severe renal dysfunction should be performed with significant caution, as the risks of repair may outweigh the benefits in this population. Further study is needed to better delineate the risks of medical management for these conditions in patients with coexisting severe renal dysfunction. Lastly, current guidelines for the management of vascular diseases, including objective performance goals for critical limb ischemia, are likely not applicable in patients with severe renal insufficiency.

Preoperative evaluation of the vascular surgery patient

Patients undergoing vascular surgery present a myriad of perioperative challenges due to the complex comorbidities affecting them in conjunction with high-risk surgical procedures. Additionally, advances in endovascular technology have enabled surgical procedures to be performed on patients who would not have been considered surgical candidates in the past. This combination of increasing patient morbidity and evolving surgical technique requires a well-planned preoperative assessment and close communication with surgical and perioperative colleagues. This article outlines an appropriate approach by first considering each organ system, followed by review of considerations unique to various surgical procedures, and then an overall assessment of risk.

Statins Promote Residual Aneurysm Sac Regression Following Endovascular Aortic Aneurysm Repair

Background:

Regression of the residual sac is indicative of successful endovascular aortic aneurysm (EVAR) repair. Using color duplex ultrasound (CDU), we monitored the residual aneurysm sac following EVAR and correlated sac behavior with perioperative risk factors.

Methods:

Of 145 patients with EVAR, 106 (73.1%) patients between January 01, 2003, and July 01, 2010, had at least 2 consecutive postoperative scans and thus were eligible for inclusion. Mean (± standard deviation [SD]) CDU scans per person was 4.6 (±1.4). All were conducted by the same technologist using a standard protocol on the same machine. Aneurysm sac change in centimeters and percentage terms was calculated. The presence or absence of an endoleak was also recorded. Change in aneurysm sac size was correlated with preoperative risk factors.

Findings:

Mean sac size change at 1 month was a decrease of 0.24 cm, equating to a percentage change of 4.3%. At 7 months, the decrease was 0.59 cm (9.8%), at 12 months, 0.73 cm (12.4%), at 18 months 0.92 cm (15.8%), and at 36 months 1.0 cm (16.6%). Both univariate and multivariate analyses demonstrated that statin therapy ( P = .002) was the only risk factor variable positively associated with aneurysm regression while the presence of an endoleak was inversely related to sac reduction ( P = .01).

Interpretation:

Maximum aneurysmal sac reduction seems to occur in the first year following endograft implantation. Statin therapy appears to be associated with an increased likelihood of sac regression following EVAR. Further investigation of the role of statins in the biology of abdominal aortic aneurysmal disease is warranted.

[Interventional endovascular therapy of infrarenal abdominal aortic aneurysm]

The catheter-based interventional therapy (endovascular aortic repair EVAR) of abdominal aortic aneurysms (AAA) has gained an established place in the spectrum of therapeutic options. The procedure is characterized by low peri-interventional morbidity and mortality. Multislice computed tomography (CT) has a dominant role in defining the correct indications and in selecting an appropriate stent graft prior to the intervention. The rate of acute conversions could be reduced from 2.9 % to 0 % in our own elective patient population since 2010. In our vascular centre the proportion of patients treated by EVAR was 39.5 % (102 out of 258). The procedure is used routinely in patients who have an increased risk for general anesthesia or open surgery due to concomitant diseases. It is also used in patients with a reduced local operability due to prior surgery, abdominal diseases or radiation therapy. Arterial closure devices allow a completely percutaneous approach in a certain group of patients. However, after EVAR a life-long surveillance is mandatory because delayed therapy failure has been described. In younger patients who do not have a higher risk open surgery is still an option. The paper describes techniques, results und complications of EVAR.

Statins and noncardiac vascular disease

PURPOSE OF REVIEW

To discuss the beneficial effects of statin treatment in patients with peripheral arterial disease (PAD), abdominal aortic aneurysms (AAAs), atherosclerotic renal artery stenosis (ARAS) and carotid artery disease.

RECENT FINDINGS

Evidence suggests that statins may reduce the progression (or even reverse the development) of carotid artery stenosis and AAAs. Statins also improve several indices (e.g. serum creatinine) and preserve renal function in ARAS. In patients with PAD, statins are associated with improved claudication distance and time, reduced cardiovascular events, and improved graft patency rates should these patients undergo surgery. Finally, statins are associated with improved perioperative and long-term morbidity and mortality rates in all vascular patients whether they undergo surgery or endovascular procedures.

SUMMARY

Routine statin treatment should be implemented for all vascular patients to ensure a reduced progression of their disease, as well as a reduction in cardiovascular events.

Association between preoperative statin therapy and postoperative change in glomerular filtration rate in endovascular aortic surgery

BACKGROUND

Acute kidney injury during endovascular aortic repair can result in a reduction in the postoperative glomerular filtration rate (GFR). The 'pleiotropic' effects of statins offer a potential mechanism of reducing the postoperative decline in the GFR. We therefore tested the hypothesis that in patients undergoing endovascular aortic repair, the GFR decreases less in patients taking preoperative statins than in those who do not.

METHODS

A cohort investigation of 501 consecutive patients who underwent endovascular aortic repair between June 2005 and March 2007 in an academic tertiary care centre. Multivariable linear regression was used to assess the association between the statin use and the postoperative GFR, after adjusting for the baseline GFR and other confounding covariables selected using a stepwise criterion.

RESULTS

The statin use was not associated with a change in the postoperative GFR (P=0.94); the difference (95% confidence interval) in the mean postoperative GFR (statins minus no statins) was estimated at 0.1 (-3.1, +3.4) ml min(-1) 1.73 m(-2). A decrease in the GFR of ≥ 25% (the threshold to diagnose contrast-induced nephropathy) developed in 26 of 192 patients given statins before operation (13.5%) compared with 36 of 296 patients who were not taking statins (12.2%).

CONCLUSIONS

Statin therapy is not associated with a statistically significant change in the mean postoperative GFR in patients undergoing endovascular aortic surgery, nor a reduction in the risk of a GFR decline of >25%.

Renal dysfunction and fluid and electrolyte disturbances

PURPOSE OF REVIEW

To examine recent developments in preventing and treating postoperative acute renal dysfunction. To review contemporary issues concerning perioperative fluid and electrolyte management.

RECENT FINDINGS

Renal dysfunction remains a major postoperative morbidity despite the advent of intermittent and continuous renal replacement therapies. It is also associated with increased mortality. Newer techniques, such as off-pump coronary artery bypass surgery, which promised to reduce the incidence of postoperative renal injury, have failed to do so. In addition, newer techniques such as endovascular repair of aortic disorder and the transcutaneous insertion of aortic valves are associated with substantial degrees of kidney injury partially due to the use of much intravenous contrast material. Therefore, the present-day approach to preventing contrast-induced nephropathy is reviewed. Electrolyte disturbances are especially problematic after certain types of surgery, such as trans-sphenoidal adenomectomy and surgeries requiring the use of large volumes of irrigating solutions.

SUMMARY

Renal dysfunction, along with fluid and electrolyte disturbances, is a major issue that needs to be considered as part of perioperative management. Moreover, it is the prevention of clinically significant renal injury and electrolyte disturbances that is the cornerstone of contemporary anesthetic and surgical care.

[The role of statins in atherosclerotic peripheral arterial disease]

The use of statins for secondary prevention in patients with peripheral (extracoronary) arterial disease is not widespread. Their possible use has only relatively recently been studied and data in the literature are sometimes controversial or are not disclosed. The aim of this paper is to review the recent literature and to discuss possible reasons for using statins in patients with extracoronary atherosclerotic arterial involvement, focusing on the areas in which they have been investigated. The main conclusions are that statins should be prescribed with the objective of reducing coronary and cerebrovascular morbidity and mortality in patients with carotid disease, abdominal aortic aneurysm and lower limb occlusive disease. There is sufficient evidence to suggest a reduction in the perioperative risk of vascular surgery when statins are used, and in patients with carotid stenosis they also appear to reduce perioperative risk in endarterectomy. Nevertheless, there are insufficient data to recommend the use of statins to control post-endarterectomy restenosis. In patients with intermittent claudication, statins improve walking distance and may be used for this purpose. Finally, there is insufficient evidence to recommend statins to prevent restenosis in lower limb revascularization procedures, to control progression of abdominal aortic aneurysms, or to reduce the severity of renal artery stenosis or renal dysfunction.

Innovations in treating aortic diseases: the abdominal aorta

Patients with an abdominal aortic aneurysm (AAA) could benefit from earlier diagnosis to improve long-term outcomes. Candidate serum biomarkers for earlier AAA diagnosis include D-dimer, fibrinogen, low-density lipoprotein, high-density lipoprotein, lipoprotein(a), and the proteolytic enzymes known as matrix metalloproteinases. Furthermore, biomarkers such as brain natriuretic peptide significantly stratify perioperative risk in AAA repair. Statins significantly improve outcomes after AAA repair. They may also significantly slow AAA growth to allow pharmacologic arrest of AAA development. Recent trials have focused attention on fluid management for AAA repair. Although restrictive fluid management may significantly improve clinical outcomes, current evidence does not clearly support crystalloid or colloid for AAA repair. There may be an increased risk of renal dysfunction associated with hetastarch therapy. Endovascular repair has revolutionized the clinical management of AAAs. Recent trials have shown its significant outcome advantages. Furthermore, it is also applicable in high-risk operative cohorts and, in the future, may be suited for earlier AAA repair. This technology continues to advance with the development of branched and fenestrated grafts as well as total percutaneous endovascular AAA repair. Regardless of these advances, the clinical management of endoleaks will remain a major clinical focus. Taken together, these advances in the management of AAAs likely will significantly influence future clinical approaches to this challenging patient cohort.