N-terminal pro-brain natriuretic peptide and angiotensin-converting enzyme-2 levels and their association with postoperative cardiac complications after emergency orthopedic surgery

ESAIC focused guideline for the use of cardiac biomarkers in perioperative risk evaluation

BACKGROUND

In recent years, there has been increasing focus on the use of cardiac biomarkers in patients undergoing noncardiac surgery.

AIMS

The aim of this focused guideline was to provide updated guidance regarding the pre-, post- and combined pre-and postoperative use of cardiac troponin and B-type natriuretic peptides in adult patients undergoing noncardiac surgery.

METHODS

The guidelines were prepared using Grading of Recommendations Assessment Development and Evaluation (GRADE) methodology. This included the definition of critical outcomes, a systematic literature search, appraisal of certainty of evidence, evaluation of biomarker measurement in terms of the balance of desirable and undesirable effects including clinical outcomes, resource use, health inequality, stakeholder acceptance, and implementation. The panel differentiated between three different scopes of applications: cardiac biomarkers as prognostic factors, as tools for risk prediction, and for biomarker-enhanced management strategies.

RESULTS

In a modified Delphi process, the task force defined 12 critical outcomes. The systematic literature search resulted in over 25,000 hits, of which 115 full-text articles formed the body of evidence for recommendations. The evidence appraisal indicated heterogeneity in the certainty of evidence across critical outcomes. Further, there was relevant gradient in the certainty of evidence across the three scopes of application. Recommendations were issued and if this was not possible due to limited evidence, clinical practice statements were produced.

CONCLUSION

The ESAIC focused guidelines provide guidance on the perioperative use of cardiac troponin and B-type natriuretic peptides in patients undergoing noncardiac surgery, for three different scopes of application.

Postoperative elevated cardiac troponin levels predict all-cause mortality and major adverse cardiovascular events following noncardiac surgery: A dose-response meta-analysis of prospective studies

STUDY OBJECTIVE

To perform a dose-response meta-analysis for the association between postoperative myocardial injury (PMI) in noncardiac surgery and the risk of all-cause mortality or major adverse cardiovascular event (MACE).

DESIGN

Dose-response meta-analysis of prospective studies with weighted (WL) or generalized (GL) linear and restricted cubic spline (RCS) regression.

SETTING

Teaching hospitals.

PATIENTS

Adult patients undergoing noncardiac surgery.

INTERVENTIONS

No.

MEASUREMENTS

The primary outcome was all-cause mortality. The secondary outcome was MACE.

MAIN RESULTS

29 studies (53,518 patients) were included. The overall incidence of PMI was 26.0% (95% CI 21.0% to 32.0%). Compared to those without PMI, patients with PMI had an increased risk of all-cause mortality at short- (<12 months) (cardiac troponin[cTn]I: unadj OR 1.71,95%CI 1.22 to 2.41, P < 0.001; cTnT: unadj OR 2.33,95%CI 2.07 to 2.63, P < 0.001), and long-term (≥ 12 months) (cTnI: unadj OR 1.80, 95%CI 1.63 to 1.99; cTnT: unadj OR 1.47,95%CI 1.33 to 1.62) (All P < 0.001) follow-up. For MACE, the group with elevated values was associated with an increased risk (cTnI: unadj OR 1.98, 95% CI 1.13 to 3.47, P = 0.018; cTnT: unadj OR 2.29, 95% CI 1.88 to 2.79, P < 0.001). Dose-response analysis showed positive associations between PMI (per 1× upper reference limit[URL] increment) and all-cause mortality both at short- (unadj OR) (WL, OR 1.09, 95% CI 1.09 to 1.10; GL, OR 1.06, 95% CI 1.06 to 1.07; RCS in the range of 1-2× URL, OR = 2.43, 95%CI 2.25 to 2.62) and long-term follow-up (unadj HR) (WL, OR 1.16, 95% CI 1.14 to 1.17; GL, OR 1.15, 95% CI 1.13 to 1.16; RCS in the range of 1-2.75× URL, OR = 1.23, 95%CI 1.13 to 1.33), and MACE at longest follow-up (unadj OR) (WL: OR 1.53, 95% CI 1.49 to 1.57; GL: OR 1.46, 95% CI 1.42 to 1.50; RCS in the range of 1-2 x URL, OR = 3.10, 95%CI 2.51 to 3.81) (All P < 0.001). For mild cTn increase below URL, the risk of mortality increased with every increment of 0.25xURL (WL, OR 1.03, 95% CI 1.02 to 1.03; GL, OR 1.05, 95% CI 1.03 to 1.07; RCS in the range of 0-0.5 URL, OR = 9.41, 95% CI 7.41 to 11.95) (All P < 0.001).

CONCLUSIONS

This study shows positive WL or GL and RCS dose-response relationships between PMI and all-cause mortality at short (< 12 mons)- and long-term (≥ 12 mons) follow-up, and MACE at longest follow-up. For mild cTn increase below URL, the risk of mortality also increases even with every increment of 0.25× URL.

Preadmission Statin Prescription and Inpatient Myocardial Infarction in Geriatric Hip Fracture

Statins have been shown to reduce myocardial infarction (MI) in cardiac and vascular surgery. MI is common in hip fracture. This study aims to investigate whether statins decrease MI in hip fracture surgery and reduce mortality resulting from MI. Patients aged 65 years and above with a low-energy hip fracture were identified between January 2015 and December 2017. Demographics, comorbidities, predictive scores, medications and outcomes were assessed retrospectively. The primary outcome was inpatient MI. The secondary outcome was inpatient mortality resulting from MI, for which fatal and non-fatal MI were modelled. Regression analysis was conducted with propensity score weighting. Hip fracture occurred in 1166 patients, of which 391 (34%) were actively taking statins. Thirty-one (2.7%) patients were clinically diagnosed with MI. They had a higher inpatient mortality than those who did not sustain an MI (35% vs. 5.3%, p < 0.0001). No reduction was seen between statin use and the occurrence of MI (OR = 0.97, 95% CI: 0.45-2.11; p = 0.942) including Fluvastatin-equivalent dosage (OR = 1.00, 95% CI: 0.96-1.03, p = 0.207). Statins were not associated with having a non-fatal MI (OR 1.47, 95% CI: 0.58-3.71; p = 0.416) or preventing fatal MI (OR = 0.40, 95% CI: 0.08-1.93; p = 0.255). Preadmission statin use and associations with clinically diagnosed inpatient MI or survival after inpatient MI were not able to be established.

Vasculopathy and Coagulopathy Associated with SARS-CoV-2 Infection

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), has resulted in > 500,000 deaths worldwide, including > 125,000 deaths in the U.S. since its emergence in late December 2019 and June 2020. Neither curative anti-viral drugs nor a protective vaccine is currently available for the treatment and prevention of COVID-19. Recently, new clinical syndromes associated with coagulopathy and vasculopathy have emerged as a cause of sudden death and other serious clinical manifestations in younger patients infected with SARS-CoV-2 infection. Angiotensin converting enzyme 2 (ACE2), the receptor for SARS-CoV-2 and other coronaviruses, is a transmembrane protein expressed by lung alveolar epithelial cells, enterocytes, and vascular endothelial cells, whose physiologic role is to induce the maturation of angiotensin I to generate angiotensin 1-7, a peptide hormone that controls vasoconstriction and blood pressure. In this review, we provide the general context of the molecular and cellular mechanisms of SARS-CoV-2 infection with a focus on endothelial cells, describe the vasculopathy and coagulopathy syndromes in patients with SARS-CoV-2, and outline current understanding of the underlying mechanistic aspects.

Imbalance of the renin-angiotensin system may contribute to inflammation and fibrosis in IBD: a novel therapeutic target?

OBJECTIVE

We evaluated the influence of the renin-angiotensin system (RAS) on intestinal inflammation and fibrosis.

DESIGN

Cultured human colonic myofibroblast proliferation and collagen secretion were assessed following treatment with angiotensin (Ang) II and Ang (1-7), their receptor antagonists candesartan and A779, and the ACE inhibitor captopril. Circulating and intestinal RAS components were evaluated in patients with and without IBD. Disease outcomes in patients with IBD treated with ACE inhibitors and angiotensin receptor blockers (ARBs) were assessed in retrospective studies.

RESULTS

Human colonic myofibroblast proliferation was reduced by Ang (1-7) in a dose-dependent manner (p<0.05). Ang II marginally but not significantly increased proliferation, an effect reversed by candesartan (p<0.001). Colonic myofibroblast collagen secretion was reduced by Ang (1-7) (p<0.05) and captopril (p<0.001), and was increased by Ang II (p<0.001). Patients with IBD had higher circulating renin (mean 25.4 vs 18.6 mIU/L, p=0.026) and ACE2:ACE ratio (mean 0.92 vs 0.69, p=0.015) than controls without IBD. RAS gene transcripts and peptides were identified in healthy and diseased bowels. Colonic mucosal Masson's trichrome staining correlated with Ang II (r=0.346, p=0.010) and inversely with ACE2 activity (r=-0.373, p=0.006). Patients with IBD who required surgery (1/37 vs 12/75, p=0.034) and hospitalisation (0/34 vs 8/68, p=0.049) over 2 years were less often treated with ACE inhibitors and ARBs than patients not requiring surgery or hospitalisation.

CONCLUSIONS

The RAS mediates fibrosis in human cell cultures, is expressed in the intestine and perturbed in intestinal inflammation, and agents targeting this system are associated with improved disease outcomes.

Risk factors for major adverse cardiovascular events after osteoporotic hip fracture repair surgery

Osteoporotic hip fracture (OHF) is an increasingly frequent age-related pathology, which results in high rates of functional loss and mortality within the first year after surgery. This study assessed whether preoperative levels of brain natriuretic peptide (NT-proBNP) and troponin I were related to early occurrence (30d) of major adverse cardio-vascular events (MACE) after OHF repair surgery. During a 6-month period, perioperative clinical and analytical data from consecutive patients, without known history of cardiovascular disease and undergoing surgery for OHF repair at a single centre, were prospectively collected. MACE was defined as acute myocardial ischaemia or infarction, acute heart failure or cardiovascular death. amongst the 140 patients included, 23 (16.4%) developed postoperative MACE (MACE group) and 117 did not (Control group). Compared to those from control group, patients from MACE group were older, had poorer physical status (ASA III-IV), received preoperative red blood cell transfusion (RBCT) more frequently, presented with lower haemoglobin concentrations and higher NT-proBNP, creatinine and troponin I concentrations. Overall, RBCT requirements and 30d mortality rate were also higher in MACE group. However, in multivariate analysis, only preoperative RBCT, creatinine >1 mg/dL and NT-proBNP >450 pg/mL remained as independent preoperative risks factors for postoperative MACE, while 95% confidence intervals of odds ratios were wide. Though our findings require confirmation in a larger multicentre cohort, identifying risk factors for early postoperative MACE after OHF repair surgery, might facilitate assessing patients' risk prior to and following surgery, and targeting them the appropriate preventive and/or therapeutic interventions.

Troponin elevations after non-cardiac, non-vascular surgery are predictive of major adverse cardiac events and mortality: a systematic review and meta-analysis

BACKGROUND

Patients undergoing non-cardiac, non-vascular surgery are at risk of major cardiovascular complications. In non-cardiac surgery, troponin elevation has previously been shown to be an independent predictor of major adverse cardiac events and postoperative mortality; however, a majority of studies have focused on vascular surgery patients. The aim of this meta-analysis was to determine whether troponin elevation is a predictor of major adverse cardiac events and mortality within 30 days and 1 yr after non-cardiac, non-vascular surgery.

METHODS

A systematic review and meta-analysis was conducted in January 2016 according to the Meta-analysis Of Observational Studies in Epidemiology guidelines. Both interventional and observational studies measuring troponin within the first 4 days after surgery were eligible. A systematic search was performed in PubMed, EMBASE, Scopus, and the Cochrane Central Register of Controlled Trials.

RESULTS

Eleven eligible clinical studies (n=2193) were identified. A postoperative troponin elevation was a predictor of 30 day mortality, odds ratio (OR) 3.52 [95% confidence interval (CI) 2.21-5.62; I²=0%], and an independent predictor of 1 yr mortality, adjusted OR 2.53 (95% CI 1.20-5.36; I²=26%). A postoperative troponin elevation was associated with major adverse cardiac events at 30 days, OR 5.92 (95% CI 1.67-20.96; I²=86%), and 1 yr after surgery, adjusted OR 3.00 (95% CI 1.43-6.29; I²=21%).

CONCLUSIONS

Postoperative myocardial injury is an independent predictor of major adverse cardiac events and mortality within 30 days and 1 yr after non-cardiac, non-vascular surgery. The meta-analysis provides evidence that supports troponin monitoring as a cardiovascular risk stratification tool.

Elevated plasma angiotensin converting enzyme 2 activity is an independent predictor of major adverse cardiac events in patients with obstructive coronary artery disease

Background

Angiotensin converting enzyme 2 (ACE2) is an endogenous regulator of the renin angiotensin system. Increased circulating ACE2 predicts adverse outcomes in patients with heart failure (HF), but it is unknown if elevated plasma ACE2 activity predicts major adverse cardiovascular events (MACE) in patients with obstructive coronary artery disease (CAD).

Methods

We prospectively recruited patients with obstructive CAD (defined as ≥50% stenosis of the left main coronary artery and/or ≥70% stenosis in ≥ 1 other major epicardial vessel on invasive coronary angiography) and measured plasma ACE2 activity. Patients were followed up to determine if circulating ACE2 activity levels predicted the primary endpoint of MACE (cardiovascular mortality, HF or myocardial infarction).

Results

We recruited 79 patients with obstructive coronary artery disease. The median (IQR) plasma ACE2 activity was 29.3 pmol/ml/min [21.2–41.2]. Over a median follow up of 10.5 years [9.6–10.8years], MACE occurred in 46% of patients (36 events). On Kaplan-Meier analysis, above-median plasma ACE2 activity was associated with MACE (log-rank test, p = 0.035) and HF hospitalisation (p = 0.01). After Cox multivariable adjustment, log ACE2 activity remained an independent predictor of MACE (hazard ratio (HR) 2.4, 95% confidence interval (CI) 1.24–4.72, p = 0.009) and HF hospitalisation (HR: 4.03, 95% CI: 1.42–11.5, p = 0.009).

Conclusions

Plasma ACE2 activity independently increased the hazard of adverse long-term cardiovascular outcomes in patients with obstructive CAD.

Cardiac Biomarkers Predict 1-Year Mortality in Elderly Patients Undergoing Hip Fracture Surgery

This prospective study included 152 elderly patients (mean age, 80 years; range, 72-88 years) with a hip fracture treated surgically. Comorbidities were evaluated, and B-type natriuretic peptide was measured at baseline and at postoperative days 4 and 5 in addition to troponin I. Major cardiac events were recorded, and 1-year mortality was assessed. Comorbidity models with the important multivariate predictors of 1-year mortality were analyzed. Overall, 9 patients (6%) experienced major cardiac events postoperatively during their hospitalization. Three patients (2%) died postoperatively, at days 5, 7, and 10, from autopsy-confirmed myocardial infarction. Three patients (2%) experienced a nonfatal myocardial infarction, and 3 patients (2%) experienced acute heart failure. At 1-year follow-up, 37 patients (24%) had died. Age older than 80 years (P=.000), renal failure (P=.016), cardiovascular disease (P=.003), respiratory disease (P=.010), Parkinson disease (P=.024), and dementia (P=.000) were univariate predictors of 1-year mortality. However, in the multivariate model, only age older than 80 years (P=.000) and dementia (P=.024) were important predictors of 1-year mortality. In all comorbidity models, age older than 80 years and dementia were important predictors of 1-year mortality. Postoperative increase in B-type natriuretic peptide was the most important predictor of 1-year mortality. Receiver operating characteristic curve analysis showed a threshold of 90 ng/mL of preoperative B-type natriuretic peptide (area under the curve=0.773, 95% confidence interval, 0.691-0.855, P<.001) had 82% sensitivity and 62% specificity to predict 1-year mortality. Similarly, a threshold of 190 ng/mL of postoperative B-type natriuretic peptide (area under the curve=0.753, 95% confidence interval, 0.662-0.844, P<.001) had 70% sensitivity and 77% specificity to predict the study endpoint. [Orthopedics. 2017; 40(3):e417-e424.].

Serum protease activity in chronic kidney disease patients: The GANI_MED renal cohort

Serum or plasma proteases have been associated with various diseases including cancer, inflammation, or reno-cardiovascular diseases. We aimed to investigate whether the enzymatic activities of serum proteases are associated with the estimated glomerular filtration rate (eGFR) in patients with different stages of chronic kidney disease (CKD). Our study population comprised 268 participants of the "Greifswald Approach to Individualized Medicine" (GANI_MED) cohort. Enzymatic activity of aminopeptidase A, aminopeptidase B, alanyl (membrane) aminopeptidase, insulin-regulated aminopeptidase, puromycin-sensitive aminopeptidase, leucine aminopeptidase 3, prolyl-endopeptidase (PEP), dipeptidyl peptidase 4 (DPP4), angiotensin I-converting enzyme, and angiotensin I-converting enzyme 2 (ACE2) proteases was measured in serum. Linear regression of the respective protease was performed on kidney function adjusted for age and sex. Kidney function was modeled either by the continuous Modification of Diet in Renal Disease (MDRD)-based eGFR or dichotomized by eGFR < 15 mL/min/1.73 m² or <45 mL/min/1.73 m², respectively. Results with a false discovery rate below 0.05 were deemed statistically significant. Among the 10 proteases investigated, only the activities of ACE2 and DPP4 were correlated with eGFR. Patients with lowest eGFR exhibited highest DPP4 and ACE2 activities. DPP4 and PEP were correlated with age, but all other serum protease activities showed no associations with age or sex. Our data indicate that ACE2 and DPP4 enzymatic activity are associated with the eGFR in patients with CKD. This finding distinguishes ACE2 and DPP4 from other serum peptidases analyzed and clearly indicates that further analyses are warranted to identify the precise role of these serum ectopeptidases in the pathogenesis of CKD and to fully elucidate underlying molecular mechanisms. Impact statement • Renal and cardiac diseases are very common and often occur concomitantly, resulting in increased morbidity and mortality. Understanding of molecular mechanisms linking both diseases is limited, available fragmentary data point to a role of the renin-angiotensin system (RAS) and, in particular, Ras-related peptidases. • Here, a comprehensive analysis of serum peptidase activities in patients with different stages of chronic kidney disease (CKD) is presented, with special emphasis given to RAS peptidases • The serum activities of the peptidases angiotensin I-converting enzyme 2 and dipeptidyl peptidase 4 were identified as closely associated with kidney function, specifically with the estimated glomerular filtration rate. The findings are discussed in the context of available data suggesting protective roles for both enzymes in reno-cardiac diseases. • The data add to our understanding of pathomechanisms underlying development and progression of CKD and indicate that both enzymes might represent potential pharmacological targets for the preservation of renal function.

Sleep apnea in total joint arthroplasty patients and the role for cardiac biomarkers for risk stratification: an exploration of feasibility

Obstructive sleep apnea (OSA) is highly prevalent in patients undergoing total joint arthroplasty (TJA) and is a major risk factor for postoperative cardiovascular complications and death. Recognizing this, the American Society of Anesthesiologists urges clinicians to implement special considerations in the perioperative care of OSA patients. However, as the volume of patients presenting for TJA increases, resources to implement these recommendations are limited. This necessitates mechanisms to efficiently risk stratify patients having OSA who may be susceptible to post-TJA cardiovascular complications. We explore the role of perioperative measurement of cardiac troponins (cTns) and brain natriuretic peptides (BNPs) in helping determine which OSA patients are at increased risk for post-TJA cardiovascular-related morbidity.

Predictive value of B-type natriuretic peptide (BNP) for adverse cardiac events in patients undergoing primary total knee arthroplasty (TKA)

BACKGROUND

B-type natriuretic peptide (BNP) is a well-known biomarker to predict cardiac events following orthopedic procedures. However, further information regarding BNP can be completed. The present study aims to determine which of preoperative, postoperative or the difference between them (DVPPB) can best predict adverse cardiac events following TKA procedure and detect possible risk factors of high level of BNP.

METHODS

Between Jan. 2012 and Jan. 2014. 1120 included patients in 3 institutions have a minimum of 2-years follow-up. All clinical characteristics related to TKA procedure were put in total joint arthroplasty registry system and analyzed finally. The cut-off value of BNP predicting patients at increased risks of cardiac events after TKA was evaluated by the Receiver Operating Characteristic (ROC) curve analysis.

RESULTS

Our results reveal DVPPB in comparison to preoperative and postoperative BNP can best predict cardiac events following primary TKA, and the optimal cut-off value was 825.5 pg/ml with the highest Youden index of 0.62. Cigarette smoking, ASA III/IV/V, prior history of cardiac events, general anesthesia, surgery time, and tourniquet time are risk factors for DVPPB > 825.5 pg/ml.

CONCLUSIONS

DVPPB in comparison to preoperative and postoperative BNP can best predict cardiac events following primary TKA. Cigarette smoking, ASA III/IV/V, prior history of cardiac events, general anesthesia, surgery time, and tourniquet time are risk factors for DVPPB > 825.5 pg/ml. We hope these results could be helpful to optimize health care among patients undergoing primary TKA.

Predicting the outcome of hip fracture patients by using N-terminal fragment of pro-B-type natriuretic peptide

OBJECTIVE

To examine the prognostic value of perioperative N-terminal fragment of pro-brain natriuretic peptide (NT-proBNP) in hip fracture patients.

DESIGN

Blinded prospective cohort study.

SETTING

Single centre trial at Turku University Hospital in Finland.

PARTICIPANTS

Inclusion criterion was admittance to the study hospital due to hip fracture during the trial period of October 2009--May 2010. Exclusion criteria were the patient's refusal and inadequate laboratory tests. The final study population consisted of 182 patients.

PRIMARY AND SECONDARY OUTCOME MEASURES

NT-proBNP was assessed once during the perioperative period and later if clinically indicated, and troponin T (TnT) and ECG recordings were evaluated repeatedly. The short-term (30-day) and long-term (1000 days) mortalities were studied.

RESULTS

Median (IQR) follow-up time was 3.1 (0.3) years. The median (IQR) NT-proBNP level was 1260 (2298) ng/L in preoperative and 1600 (3971) ng/L in postoperative samples (p=0.001). TnT was elevated in 66 (36%) patients, and was significantly more common in patients with higher NT-proBNP. Patients with high (>2370 ng/L) and intermediate (806-2370 ng/L) NT-proBNP level had significantly higher short-term mortality compared with patients having a low (<806 ng/L) NT-proBNP level (15 vs 11 vs 2%, p=0.04), and the long-term mortality remained higher in these patients (69% vs 49% vs 27%, p<0.001). Intermediate or high NT-proBNP level (HR 7.8, 95% CI 1.03 to 59.14, p<0.05) was the only independent predictor of short-term mortality, while intermediate or high NT-proBNP level (HR 2.27, 95% CI 1.30 to 3.96, p=0.004), the presence of dementia (HR 1.74, 95% CI 1.13 to 2.66, p=0.01) and higher preoperative American Society of Anesthesiologists' (ASA) classification (HR 1.59, 95% CI 1.06 to 2.38, p=0.02) were independent predictors of long-term mortality.

CONCLUSION

An elevated perioperative NT-proBNP level is common in hip fracture patients, and it is an independent predictor of short-term and long-term mortality superior to the commonly used clinical risk scores.

TRIAL REGISTRATION NUMBER

NCT01015105; Results.

N-terminal pro-B-type Natriuretic Peptides’ Prognostic Utility Is Overestimated in Meta-analyses Using Study-specific Optimal Diagnostic Thresholds

Background:

N-terminal fragment B-type natriuretic peptide (NT-proBNP) prognostic utility is commonly determined post hoc by identifying a single optimal discrimination threshold tailored to the individual study population. The authors aimed to determine how using these study-specific post hoc thresholds impacts meta-analysis results.

Methods:

The authors conducted a systematic review of studies reporting the ability of preoperative NT-proBNP measurements to predict the composite outcome of all-cause mortality and nonfatal myocardial infarction at 30 days after noncardiac surgery. Individual patient-level data NT-proBNP thresholds were determined using two different methodologies. First, a single combined NT-proBNP threshold was determined for the entire cohort of patients, and a meta-analysis conducted using this single threshold. Second, study-specific thresholds were determined for each individual study, with meta-analysis being conducted using these study-specific thresholds.

Results:

The authors obtained individual patient data from 14 studies (n = 2,196). Using a single NT-proBNP cohort threshold, the odds ratio (OR) associated with an increased NT-proBNP measurement was 3.43 (95% CI, 2.08 to 5.64). Using individual study-specific thresholds, the OR associated with an increased NT-proBNP measurement was 6.45 (95% CI, 3.98 to 10.46). In smaller studies (&lt;100 patients) a single cohort threshold was associated with an OR of 5.4 (95% CI, 2.27 to 12.84) as compared with an OR of 14.38 (95% CI, 6.08 to 34.01) for study-specific thresholds.

Conclusions:

Post hoc identification of study-specific prognostic biomarker thresholds artificially maximizes biomarker predictive power, resulting in an amplification or overestimation during meta-analysis of these results. This effect is accentuated in small studies.

From gene to protein-experimental and clinical studies of ACE2 in blood pressure control and arterial hypertension

Hypertension is a major risk factor for stroke, coronary events, heart and renal failure, and the renin-angiotensin system (RAS) plays a major role in its pathogenesis. Within the RAS, angiotensin converting enzyme (ACE) converts angiotensin (Ang) I into the vasoconstrictor Ang II. An “alternate” arm of the RAS now exists in which ACE2 counterbalances the effects of the classic RAS through degradation of Ang II, and generation of the vasodilator Ang 1-7. ACE2 is highly expressed in the heart, blood vessels, and kidney. The catalytically active ectodomain of ACE2 undergoes shedding, resulting in ACE2 in the circulation. The ACE2 gene maps to a quantitative trait locus on the X chromosome in three strains of genetically hypertensive rats, suggesting that ACE2 may be a candidate gene for hypertension. It is hypothesized that disruption of tissue ACE/ACE2 balance results in changes in blood pressure, with increased ACE2 expression protecting against increased blood pressure, and ACE2 deficiency contributing to hypertension. Experimental hypertension studies have measured ACE2 in either the heart or kidney and/or plasma, and have reported that deletion or inhibition of ACE2 leads to hypertension, whilst enhancing ACE2 protects against the development of hypertension, hence increasing ACE2 may be a therapeutic option for the management of high blood pressure in man. There have been relatively few studies of ACE2, either at the gene or the circulating level in patients with hypertension. Plasma ACE2 activity is low in healthy subjects, but elevated in patients with cardiovascular risk factors or cardiovascular disease. Genetic studies have investigated ACE2 gene polymorphisms with either hypertension or blood pressure, and have produced largely inconsistent findings. This review discusses the evidence regarding ACE2 in experimental hypertension models and the association between circulating ACE2 activity and ACE2 polymorphisms with blood pressure and arterial hypertension in man.

Predictive value of plasma brain natriuretic peptide for postoperative cardiac complications--a systemic review and meta-analysis

BACKGROUND

We aimed to undertake a systematic review and meta-analysis of studies addressing perioperative natriuretic peptide (NP) levels to predict postoperative major adverse cardiac events (MACE) after major surgery.

METHODS

We searched MEDLINE and Embase with no language restrictions up to May 2013. The end points were major cardiac complications. We summarized test performance characteristics with the use of forest plots, hierarchical summary receiver operating characteristic curves, and bivariate random effects models.

RESULTS

Of the 662 retrieved articles, 24 studies satisfied the predefined eligibility criteria, including 5438 patients along with 712 (13.1%) events. After major surgery, the diagnostic odds ratio (DOR) of NP in predicting postoperative MACE was 14.3 (95% confidence interval [CI], 9.87-20.7) for overall population, 13.9 (8.43-22.8) for patients undergoing cardiac surgery, and 15.0 (8.84-25.5) for patients undergoing noncardiac surgery. The pooled sensitivity was 0.84 (95% CI, 0.79-0.88) and specificity was 0.76 (95% CI, 0.71-0.81). Postoperative measurement (DOR, 18.9; 7.68-46.3) was associated with higher predictive value than preoperative measurement (DOR, 13.6; 7.68-46.3). Results were similar for a subgroup with the composite outcome including mortality (DOR, 16.4; 10.6-25.5). B-type natriuretic peptide was associated with higher predictive accuracy (area under the summary receiver operating characteristic, 0.84; 0.81-0.87) than N-terminal pro-b-type natriuretic peptide (area under the summary receiver operating characteristic, 0.90; 0.87-0.92).

CONCLUSIONS

The existing literature suggests that perioperative NP testing have reasonable accuracy and can be useful in perioperative risk stratification. Natriuretic peptide testing has high rule-out value and low rule-in value for predicting postoperative MACE. Medical decisions should be made in the context of these characteristics.

Upregulation of circulating components of the alternative renin-angiotensin system in inflammatory bowel disease: A pilot study

INTRODUCTION

The relationship between intestinal inflammation and circulating components of the renin-angiotensin system (RAS) is poorly understood.

MATERIALS AND METHODS

Demographic and clinical data were obtained from healthy controls and patients with inflammatory bowel disease (IBD). Plasma concentrations of the classical RAS components (angiotensin-converting enzyme (ACE) and angiotensin II (Ang II)) and alternative RAS components (ACE2 and angiotensin (1-7) (Ang (1-7))) were analysed by radioimmuno- and enzymatic assays. Systemic inflammation was assessed using serum C-reactive protein (CRP), white cell count, platelet count and albumin, and intestinal inflammation by faecal calprotectin.

RESULTS

Nineteen healthy controls (11 female; mean age 38 years, range 23-68), 19 patients with Crohn's disease (11 female; aged 45 years, range 23-76) and 15 patients with ulcerative colitis (6 female; aged 42 years, 26-64) were studied. Circulating classical RAS component levels were similar across the three groups, whereas ACE2 activity and Ang (1-7) concentrations were higher in patients with IBD compared to controls (ACE2: 21.5 vs 13.3 pmol/ml/min, p<0.05; Ang (1-7): 22.8 vs 14.1 pg/ml, p<0.001). Ang (1-7) correlated weakly with platelet and white cell counts, but not calprotectin or CRP, in patients with IBD.

CONCLUSIONS

Circulating components of the alternative RAS are increased in patients with IBD.

The prognostic value of pre-operative and post-operative B-type natriuretic peptides in patients undergoing noncardiac surgery: B-type natriuretic peptide and N-terminal fragment of pro-B-type natriuretic peptide: a systematic review and individual patient data meta-analysis

OBJECTIVES

The objective of this study was to determine whether measuring post-operative B-type natriuretic peptides (NPs) (i.e., B-type natriuretic peptide [BNP] and N-terminal fragment of proBNP [NT-proBNP]) enhances risk stratification in adult patients undergoing noncardiac surgery, in whom a pre-operative NP has been measured.

BACKGROUND

Pre-operative NP concentrations are powerful independent predictors of perioperative cardiovascular complications, but recent studies have reported that elevated post-operative NP concentrations are independently associated with these complications. It is not clear whether there is value in measuring post-operative NP when a pre-operative measurement has been done.

METHODS

We conducted a systematic review and individual patient data meta-analysis to determine whether the addition of post-operative NP levels enhanced the prediction of the composite of death and nonfatal myocardial infarction at 30 and ≥180 days after surgery.

RESULTS

Eighteen eligible studies provided individual patient data (n = 2,179). Adding post-operative NP to a risk prediction model containing pre-operative NP improved model fit and risk classification at both 30 days (corrected quasi-likelihood under the independence model criterion: 1,280 to 1,204; net reclassification index: 20%; p < 0.001) and ≥180 days (corrected quasi-likelihood under the independence model criterion: 1,320 to 1,300; net reclassification index: 11%; p = 0.003). Elevated post-operative NP was the strongest independent predictor of the primary outcome at 30 days (odds ratio: 3.7; 95% confidence interval: 2.2 to 6.2; p < 0.001) and ≥180 days (odds ratio: 2.2; 95% confidence interval: 1.9 to 2.7; p < 0.001) after surgery.

CONCLUSIONS

Additional post-operative NP measurement enhanced risk stratification for the composite outcomes of death or nonfatal myocardial infarction at 30 days and ≥180 days after noncardiac surgery compared with a pre-operative NP measurement alone.

Angiotensin-converting enzyme 2 activity in patients with chronic kidney disease

Background

Angiotensin-converting enzyme 2 (ACE2) is a novel regulator of the renin–angiotensin system that counteracts the adverse effects of angiotensin II. In heart failure patients, elevated plasma ACE2 activity predicted adverse events and greater myocardial dysfunction. We aimed to describe plasma ACE2 activity and its clinical associations in patients with kidney disease.

Methods

Patients recruited from a single centre comprised of chronic kidney disease Stage III/IV (CKD), haemodialysis patients and kidney transplant recipients (KTRs). Plasma ACE2 enzyme activity was measured using a fluorescent substrate assay in plasma, collected at baseline and stored at −80°C. Linear regression was performed in both males and females separately to determine the covariates associated with log-transformed ACE2.

Results

The median (interquartile range) plasma ACE2 activity in pmol/mL/min was 15.9 (8.4–26.1) in CKD (n = 59), 9.2 (3.9–18.2) in haemodialysis (n = 100) and 13.1 (5.7–21.9) in KTR (n = 80; P < 0.01). In male haemodialysis patients, ACE2 activity was 12.1 (6.8–19.6) compared with 4.4 (2.5–10.3) in females (P < 0.01). Log-transformed ACE2 plasma activity was associated with post-haemodialysis systolic blood pressure in females [β-coefficient 0.04, 95% confidence interval (95% CI) 0.01–0.06, P = 0.006]. In males, log-transformed ACE2 plasma activity was associated with B-type natriuretic peptide (β-coefficient 0.39, 95% CI 0.19–0.60, P < 0.001). Plasma ACE2 activity was not associated with mortality.

Conclusions

Plasma ACE2 activity is reduced in haemodialysis patients compared with CKD patients, and in female haemodialysis patients compared with male. The different associations of plasma ACE2 activity between male and female haemodialysis patients indicate that the role of ACE2 in cardiovascular disease may differ by gender.

Combination renin-angiotensin system blockade and angiotensin-converting enzyme 2 in experimental myocardial infarction: implications for future therapeutic directions

The RAS (renin-angiotensin system) is activated after MI (myocardial infarction), and RAS blockade with ACEis [ACE (angiotensin-converting enzyme) inhibitors] or ARBs (angiotensin receptor blockers) slows but does not completely prevent progression to heart failure. Cardiac ACE is increased after MI and leads to the formation of the vasoconstrictor AngII (angiotensin II). The enzyme ACE2 is also activated after MI and degrades AngII to generate the vasodilator Ang-(1-7) [angiotensin-(1-7)]. Overexpression of ACE2 offers cardioprotective effects in experimental MI, but there is conflicting evidence as to whether the benefits of ACEis and ARBs are mediated through increasing ACE2 after MI. In the present study, we assessed the effect of an ACEi and ARB, alone and in combination, on cardiac ACE2 in a rat MI model. MI rats received vehicle, ACEi (ramipril; 1 mg/kg of body weight), ARB (valsartan; 10 mg/kg of body weight) or combination (ramipril at 1 mg/kg of body weight and valsartan at 10 mg/kg of body weight) orally for 28 days. Sham-operated rats were also studied and received vehicle alone. MI increased LV (left ventricular) mass (P<0.0001), impaired cardiac contractility (P<0.05) and activated cardiac ACE2 with increased gene (P<0.05) and protein expression (viable myocardium, P<0.05; border zone, P<0.001; infarct, P<0.05). Ramipril and valsartan improved remodelling (P<0.05), with no additional effect of dual therapy. Although ramipril inhibited ACE, and valsartan blocked the angiotensin receptor, neither treatment alone nor in combination augmented cardiac ACE2 expression. These results suggest that the cardioprotective effects of ramipril and valsartan are not mediated through up-regulation of cardiac ACE2. Strategies that do augment ACE2 after MI may be a useful addition to standard RAS blockade after MI.

The ACE2 gene: its potential as a functional candidate for cardiovascular disease

The RAS (renin–angiotensin system) plays an important role in the pathophysiology of CVD (cardiovascular disease), and RAS blockade is an important therapeutic strategy in the management of CVD. A new counterbalancing arm of the RAS is now known to exist in which ACE (angiotensin-converting enzyme) 2 degrades Ang (angiotensin) II, the main effector of the classic RAS, and generates Ang-(1–7). Altered ACE2 expression is associated with cardiac and vascular disease in experimental models of CVD, and ACE2 is increased in failing human hearts and atherosclerotic vessels. In man, circulating ACE2 activity increases with coronary heart disease, as well as heart failure, and a large proportion of the variation in plasma ACE2 levels has been attributed to hereditary factors. The ACE2 gene maps to chromosome Xp22 and this paper reviews the evidence associating ACE2 gene variation with CVD and considers clues to potential functional ACE2 variants that may alter gene expression or transcriptional activity. Studies to date have investigated ACE2 gene associations in hypertension, left ventricular hypertrophy and coronary artery disease, but the results have been inconsistent. The discrepancies may reflect the sample size of the studies, the gender or ethnicity of subjects, the cardiovascular phenotype or the ACE2 SNP investigated. The frequent observation of apparent sex-dependence might be of special importance, if confirmed. As yet, there are no studies to concurrently assess ACE2 gene polymorphisms and circulating ACE2 activity. Large-scale carefully conducted clinical studies are urgently needed to clarify more precisely the potential role of ACE2 in the CVD continuum.