Hemostatic markers before operation in patients with acutely symptomatic nonruptured and ruptured infrarenal abdominal aortic aneurysm

Plasma complement component C2: a potential biomarker for predicting abdominal aortic aneurysm related complications

Blood-based adjunctive measures that can reliably predict abdominal aortic aneurysm (AAA)-related complications hold promise for mitigating the AAA disease burden. In this pilot study, we sought to evaluate the prognostic performance of complement factors in predicting AAA-related clinical outcomes. We recruited consecutive AAA patients (n = 75) and non-AAA patients (n = 75) presenting to St. Michael's Hospital. Plasma levels of complement proteins were assessed at baseline, as well as prospectively measured regularly over a period of 2 years. The primary outcome was the incidence of rapidly progressing AAA (i.e. aortic expansion), defined as change in AAA diameter by either 0.5 cm in 6 months, or 1 cm in 12 months. Secondary outcomes included incidence of major adverse aortic events (MAAE) and major adverse cardiovascular events (MACE). All study outcomes (AAA diameter, MACE and MAAE) were obtained during follow-up. Multivariable adjusted Cox regression analyses were performed to assess the prognostic value of plasma C2 levels in patients with AAA regarding rapid aortic expansion and MAAE and MACE. Event-free survival rates of both groups were also compared. Compared to non-AAA patients, patients with AAA demonstrated significantly higher plasma concentrations of C1q, C4, Factor B, Factor H and Factor D, and significantly lower plasma concentrations of C2, C3, and C4b (p = 0.001). After a median of 24 months from initial baseline measurements, C2 was determined as the strongest predictor of rapid aortic expansion (HR 0.10, p = 0.040), MAAE (HR 0.09, p = 0.001) and MACE (HR 0.14, p = 0.011). Based on the data from the survival analysis, higher levels of C2 at admission in patients with AAA predicted greater risk for rapid aortic expansion and MAAE (not MACE). Plasma C2 has the potential to be a biomarker for predicting rapid aortic expansion, MAAE, and the eventual need for an aortic intervention in AAA patients.

Targeting Platelet Activation in Abdominal Aortic Aneurysm: Current Knowledge and Perspectives

Abdominal aortic aneurysm (AAA) is a potentially fatal vascular disease that involves complex multifactorial hemodynamic, thrombotic, inflammatory, and aortic wall remodeling processes. However, its mechanisms are incompletely understood. It has become increasingly clear that platelets are involved in pathological processes of vascular diseases beyond their role in hemostasis and thrombosis. Platelet activation with membrane receptors and secreted mediators promotes thrombus formation and the accumulation of inflammatory cells, which may play an important role in the development of AAA by destroying the structural integrity and stability of the vessel wall. Turbulent blood flow in aortic aneurysms promotes platelet activation and aggregation. Platelet count and heterogeneity are important predictive, diagnostic, and prognostic indicators of AAA. We summarize the relationship between platelet activation and AAA development and propose future research directions and possible clinical applications.

Association Between Perioperative Fibrinogen Levels and the Midterm Outcome in Patients Undergoing Elective Endovascular Repair of Abdominal Aortic Aneurysms

BACKGROUND

We investigated the potential association between perioperative fibrinogen levels and outcome in patients undergoing elective endovascular abdominal aneurysm repair (EVAR) of abdominal aortic aneurysms (AAAs).

METHODS

Consecutive patients with an intact AAA undergoing elective EVAR with a specific bifurcated endograft (Endurant, Medtronic) were recruited between December 2012 and October 2016. Preoperative and 24-hr postoperative fibrinogen levels were recorded, and potential associations with outcome were tested. Primary outcome measures included endoleaks, lower limb ischemic complications, including endograft limb occlusion, and aneurysm-related reinterventions.

RESULTS

Ninety-four patients (91 male, mean age 71.8 ± 8.0 years) with an intact AAA were enrolled in the study. The technical success was 98% (2 failures: 1 type Ia endoleak on completion angiography, 1 lower limb ischemia immediately postoperatively requiring femoral endarterectomy). There was 1 death during the first 30 days due to myocardial infarction (1%). Another patient died 15 months after the procedure from cardiac causes. During the existing follow-up (mean 14.8 ± 14.3 months), 14 patients (15%) developed an endoleak (4, type Ia endoleak and 10, type II endoleak), 6 patients (6.3%) had lower limb ischemia/endograft limb occlusion, and 10 patients (10.6%) required reintervention. Compared with the preoperative values, no significant change occurred with regard to the fibrinogen levels 24 hr after procedure (mean preoperative fibrinogen 360 ± 101 mg/dl vs 24-hr postoperative fibrinogen 349 ± 105 mg/dl, P = 0.1). Neither preoperative nor 24-hr postoperative fibrinogen levels were significantly associated with the development of endoleaks, lower limb ischemia, or reinterventions. However, the difference in fibrinogen levels (baseline to 24 hr after procedure) was significantly higher in patients with endoleaks (median -65 mg/dl vs. 15 mg/dl, P = 0.04).

CONCLUSIONS

Perioperative fibrinogen levels may play a role in predicting midterm outcomes in patients undergoing elective EVAR and appears to be associated, directly or indirectly, with the development of endoleaks. Further studies are needed to investigate these findings and explore future therapeutic implications.

Systematic Review of Circulating, Biomechanical, and Genetic Markers for the Prediction of Abdominal Aortic Aneurysm Growth and Rupture

BACKGROUND

The natural course of abdominal aortic aneurysms (AAA) is growth and rupture if left untreated. Numerous markers have been investigated; however, none are broadly acknowledged. Our aim was to identify potential prognostic markers for AAA growth and rupture.

METHODS AND RESULTS

Potential circulating, biomechanical, and genetic markers were studied. A comprehensive search was conducted in PubMed, Embase, and Cochrane Library in February 2017, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Study selection, data extraction, and methodological quality assessment were conducted by 2 independent researchers. Plausibility of markers was based on the amount of publications regarding the marker (more than 3), pooled sample size (more than 100), bias risk and statistical significance of the studies. Eighty-two studies were included, which examined circulating (n=40), biomechanical (n=27), and genetic markers (n=7) and combinations of markers (n=8). Factors with an increased expansion risk included: AAA diameter (9 studies; n=1938; low bias risk), chlamydophila pneumonia (4 studies; n=311; medium bias risk), S-elastin peptides (3 studies; n=205; medium bias risk), fluorodeoxyglucose uptake (3 studies; n=104; medium bias risk), and intraluminal thrombus size (5 studies; n=758; medium bias risk). Factors with an increased rupture risk rupture included: peak wall stress (9 studies; n=579; medium bias risk) and AAA diameter (8 studies; n=354; medium bias risk). No meta-analysis was conducted because of clinical and methodological heterogeneity.

CONCLUSIONS

We identified 5 potential markers with a prognostic value for AAA growth and 2 for rupture. While interpreting these data, one must realize that conclusions are based on small sample sizes and clinical and methodological heterogeneity. Prospective and methodological consonant studies are strongly urged to further study these potential markers.

Endovascular Aneurysm Repair-First Strategy for Ruptured Aneurysm Focuses on Fitzgerald Classification and Vein Thrombosis

BACKGROUND

Recent study have demonstrated the good results of endovascular aneurysm repair (EVAR) for ruptured abdominal aortic aneurysms (RAAAs). We report on the results of our EVAR-first strategy for RAAAs focuses on Fitzgerald (F) classification and vein thrombosis.

MATERIALS AND METHODS

From 2011 to 2017, 31 patients with RAAA underwent EVAR at our hospital. We compared F-1 patients (group A) with F-2 to F-4 patients with obvious retroperitoneal hematoma (group B).

RESULTS

The baseline characteristics in group A (n = 9) and group B (n = 22) were similar. In group B, there were 8 cases of F-2, 10 cases of F-3, and 4 cases of F-4. Of the 22 cases in group B, 16 (73%) cases involved preoperative shock. Operation time was not significantly different (group A: 147 min and group B: 131 min, P = 0.48). The total mortality rate of group A and group B combined was 77.4%. The 30-day mortality was 0% for group A and 23.8% for group B, in which there were 2 F-4 cases and 3 F-3 cases. In group B, hematoma-related complications developed in 6 cases (deep vein thrombosis: 4 cases, abdominal compartment syndrome: 1 case, and hematoma infection: 1 case), and 1 case with deep vein thrombosis developed a pulmonary embolism that resulted in cardiac arrest. The 3-year survival rate was significantly higher for group A (100% vs. 52.3%, P = 0.016), but the freedom from aortic death rate was not significantly different (100% vs. 66.7%, P = 0.056).

CONCLUSIONS

Using EVAR for RAAA is a valid strategy. Certain complications that are associated with peritoneal hematoma, especially venous thrombosis, should receive particular attention.

Biomarkers in TAA-the Holy Grail

Thoracic aortic aneurysm (TAA) is a silent disease, often discovered at a time point that dramatic complications, as rupture and dissection, occur. For the detection of asymptomatic TAA and prevention of such complications, it is essential to have an adequate screening tool. Until now, routine laboratory blood tests have played only a minor role in the screening, diagnosis, tracking and prediction of the natural history of TAAs. However, the knowledge about biomarkers is rapidly expanding in the cardiovascular field, and there are several potential biomarkers that might be implemented into TAA clinical practice in the near future. The most important and promising markers for TAA will be discussed in this overview.

In search of blood tests for thoracic aortic diseases

A number of new diagnostic screening tools have been developed for the assessment of acute and chronic diseases of the thoracic aorta. Although standardized blood-based tests capable of detecting individuals at risk for aortic aneurysm and dissection disease are not yet available, our current knowledge is expanding at a rapid rate and the future is very promising. In this review, an update of the contemporary knowledge on blood tests for detecting thoracic aortic diseases in both preclinical and clinical settings is provided, offering the potential to predict adverse aortic events, such as enlargement, rupture, and dissection.

D-dimer in patients with suspected acute mesenteric ischemia

OBJECTIVES

The aims of this study were to assess the diagnostic value of D-dimer in patients with suspected acute mesenteric ischemia (AMI) and to evaluate the correlation between D-dimer levels and the severity of bowel necrosis.

METHODS

A prospective, noninterventional study of 67 patients with clinical suspicion of AMI was performed. Measurement of D-dimer levels was performed using a latex turbidimetric method.

RESULTS

Acute mesenteric ischemia was diagnosed in 23 patients (34.3%) and non-AMI in 44 patients (65.7%). Median D-dimer levels on admission were 6.24 microg fibrinogen equivalent units (FEU)/mL (range, 0.96-53.48 microg FEU/mL) in patients with AMI and 3.45 microg FEU/mL (range, 0.50-44.69 microg FEU/mL) in non-AMI patients (P = .064). D-dimer had poor discriminative value to differentiate the presence from the absence of AMI with an area under the receiver operating characteristic curve of 0.64 (95% confidence interval, 0.50-0.78). A serum D-dimer cutoff value of 1.0 microg FEU/mL had a sensitivity of 96%, a specificity of 18%, a positive likelihood ratio of 1.17, and a negative likelihood ratio of 0.24. Among patients with AMI verified at operation, 8 had resectable bowl necrosis and 9 had unresectable bowel necrosis. There was no difference in serum D-dimer levels between resectable and unresectable bowel necrosis (P = .665).

CONCLUSIONS

Detection of serum D-dimer could not help to differentiate patient with AMI from those with non-AMI. We did not find a correlation between serum D-dimer levels and the severity of AMI. However, measurement of D-dimer levels can be of value for a small decrease in the likelihood of AMI, when the result is low.

D-dimer as a marker for early diagnosis of acute mesenteric ischemia

INTRODUCTION

Acute obstruction of mesenteric artery generally has an unfavorable prognosis because of late diagnosis. In this study we evaluated the diagnostic value of plasma D-dimer level as an early indicator in acute mesenteric ischemia in rats caused by ligation of superior mesenteric artery.

MATERIALS AND METHODS

Twenty-eight mature male Wistar rats were used in the study. These were divided into four groups, each consisting of seven rats. In group I, after performing a simple laparotomy, blood was sampled at minute 30. In group II, first the superior mesenteric artery was ligated, and blood samples were taken at the 30th minute. Group III consisted of rats undergoing a simple laparotomy and blood samples were taken 7 h later. From the subjects in group IV blood samples were obtained 7 h after the ligation of their superior mesenteric artery.

RESULTS

Plasma D-dimer levels of the ligated groups were significantly higher both at the 30th minute and the 7th hour compared to the levels of those having undergone simple laparotomies (p<0.002). Likewise, this level was higher in the 7th hour blood samples of the ligated group than in the 30th minute (p<0.008).

CONCLUSIONS

In rats undergoing acute mesenteric ischemia by ligation of superior mesenteric artery, plasma D-dimer levels increase with the duration of the intestinal ischemia period. This finding suggests that the measurement of the plasma D-dimer levels might be a useful tool for the early diagnosis of acute mesenteric obstruction.

Fibrinolysis in patients with an abdominal aortic aneurysm with special emphasis on rupture and shock

BACKGROUND

A ruptured abdominal aortic aneurysm (AAA) is associated with high mortality. Postoperative complications such as hemorrhage, multiple organ failure, myocardial infarction, and thromboembolism are common. An active and balanced hemostatic system is essential to avoid bleeding as well as thrombosis. When these activities are not properly regulated the patient is at risk of developing either excessive bleeding or thrombosis-related complications. Previous studies have shown a state of activated coagulation in patients with ruptured AAA. However, there are conflicting results regarding the fibrinolytic response.

OBJECTIVES

The aim of the present study was to investigate the fibrinolytic state pre-operatively in patients with ruptured and non-ruptured AAA in relation to the clinical outcome with special regard to the influence of shock.

METHODS

A prospective study was performed on 95 patients who underwent surgery for a ruptured AAA with shock (n = 43), a ruptured AAA without shock (n = 12), and a non-ruptured AAA (n = 40). Forty-one controls without an aneurysm were matched to the AAA patients according to age, gender and smoking habits. Plasma levels of tissue plasminogen activator antigen (tPAag), and plasminogen activator inhibitor type-1 (PAI-1) were measured as markers of fibrinolytic activity. D-dimer, a marker of fibrin turnover, was also measured.

RESULTS

D-dimer was significantly higher in patients with a non-ruptured AAA compared with controls without AAA. There were significantly higher levels of D-dimer, tPAag, and PAI-1 in patients operated for ruptured compared with non-ruptured AAA. tPAag was also significantly higher in ruptured AAA patients with shock compared with without shock. No deaths occurred in patients operated on for a non-ruptured AAA or ruptured AAA without shock. There were 12 deaths after repair of a ruptured AAA with shock, of which two patients died from bleeding and the remaining 10 from multiple organ failure and cardiac failure.

CONCLUSION

Our results indicate a state of activated coagulation in patients with a non-ruptured AAA, the state being intensified by rupture. The present data show normal fibrinolytic activities in patients with a non-ruptured AAA, but increased systemic fibrinolysis, as demonstrated by elevated tPAag level, in patients with a ruptured AAA. The elevated PAI-1 level indicates a simultaneous inhibition of the systemic fibrinolysis. Furthermore, the hyperfibrinolytic state was reinforced by shock in this study. However, the clinical outcome, with a relatively high incidence of thrombosis-related deaths, indicate a prothrombotic state instead of a hyperfibrinolytic state as a major point of attention in patients with shock as a result of a ruptured AAA.

Raised plasma fibrinogen concentration in patients with abdominal aortic aneurysm

A feature associated with abdominal aortic aneurysms (AAA) is the presence of intraluminal thrombi (ILT). Elevated plasma fibrinogen concentrations predict a greater risk of thrombosis. Therefore, the authors assessed the relationship between fibrinogen levels, AAA size, and ILT. An age- and sex-matched case-control study was conducted. Demographic data and plasma samples were obtained from 110 patients with AAA and 110 controls. All subjects had an abdominal ultrasound scan to determine the size of the aneurysm and the percentage of the ILT occupying the lumen. Plasma fibrinogen concentrations were measured by the Clauss method. Fibrinogen concentrations were significantly higher in patients with AAA than in controls (median: 2.89 vs 2.53 g/L; p<0.01). Patients with AAA who were current smokers had a larger median AAA size (4.50 vs 4.30 cm; p<0.04) and greater percentage of the ILT (40% vs 30%) than those who did not smoke. Fibrinogen was positively correlated with AAA size (r =0.323; p<0.01) and the percentage of ILT occupying the lumen (r =0.358; p<0.05). Fibrinogen levels were higher in the AAA group. The authors also demonstrated positive correlations between the AAA size, ILT, and fibrinogen concentration. Smoking was associated with larger aneurysms and ILT. Fibrinogen may be a useful marker to monitor the progression of AAA.

Preoperative antithrombin III activity predicts outcome after surgical repair of acute type A aortic dissection

BACKGROUND

Acute Stanford type A aortic dissection is associated with substantial perioperative morbidity and mortality. A sepsis-like state may lead to antithrombin (AT) III consumption and deficiency. The impact of preoperative AT III activity on outcome in patients undergoing emergency surgery is yet unknown.

METHODS

We measured preoperative AT III activity in 99 consecutive patients undergoing emergency aortic surgery for Stanford type A aortic dissection during a 4-year period in a retrospective study. Cardiovascular co-morbidities, risk factors and surgical data were recorded and patients were followed for 30-day mortality, and occurrence of multiple organ failure (MOF).

RESULTS

During the first 30 days, 15 patients (15%) died, and 8 patients (8%) had MOF. Median AT III levels (IQR) in 30-day non-survivors versus survivors were 64% (52-72) versus 90% (75-97) (p<0.001), and in patients with versus without MOF were 66% (52.3-77.3) versus 88% (72-96) (p=0.018), respectively. Adjusted odds ratios for 30-day mortality and MOF for AT III activity (per % increments) were 0.92 (p=0.007), and 0.96 (p=0.012), respectively, indicating a significant inverse relationship between AT III activity and outcome.

CONCLUSION

There is a strong inverse association between preoperative AT III activity and adverse outcome in patients undergoing surgical repair of acute Stanford type A aortic dissection. Larger studies are necessary to determine a cut-off value for AT III and to assess whether patients with low AT III levels benefit targeted therapeutic interventions.

Disseminated intravascular coagulopathy in aortic aneurysms

Aneurysm-induced disseminated intravascular coagulopathy (DIC) constitutes a rare presentation form of aortic aneurysms. The majority of DIC cases are asymptomatic and this condition is usually diagnosed during the perioperative workup; yet, in a minority of cases, DIC leads to the diagnosis of the vascular abnormality. The management of aneurysm-induced DIC is based both on the treatment of the underlying disorder and on an active scrutiny of the hemodynamic and blood support requirements. Blood replacement therapy should be individualized, guided by the clinical situation of the patient (especially considering the bleeding risk or the presence of hemorrhages), and accompanied by a close monitoring of the coagulation status. Fresh frozen plasma is usually the preferred initial option to replace coagulation factors, but fibrinogen, cryoprecipitates, and platelet concentrates are adequate options in certain contexts. Heparins, both non-fractionated and low-weight molecular types, are the most widely accepted agents for achieving adequate control of the coagulation activation and consumption. Other antithrombotic drugs are under study, including antithrombin III and activated protein C, although only the latter has demonstrated a benefit in terms of survival in a comparative, randomized context. Antifibrinolytic agents such as gabexate mesilate, tranexamic acid, and epsilon-aminocaproic acid (EACA) have been used with conflicting results. These agents may have a role for patients with catastrophic bleeding resistant to other therapeutical options, but their relevance as a first line of treatment is, at present, undefined. An assessment of the multitude of therapeutic approaches available would seem to indicate that there is a lack of standardization in the management of these patients. Multi-center, randomized clinical trials are needed to elucidate the most adequate therapy in this context.

Clinical implication of plasma level of soluble fibrin monomer-fibrinogen complex in patients with abdominal aortic aneurysm

OBJECTIVE

We prospectively studied the clinical implication of plasma level of soluble fibrin monomer (FM)-fibrinogen complex, a recently established molecular marker reflecting thrombin activity, in patients with abdominal aortic aneurysm (AAA) undergoing elective aortic repair.

METHODS

The study included 49 patients who underwent elective aneurysm repair using a gelatin-sealed or nonimpregnated Dacron prosthesis. Plasma level of soluble FM-fibrinogen complex was measured before surgery and on days 1, 3, 5, 7, and 10 postoperatively by latex agglutination assay utilizing monoclonal antibody IF-43. Plasma levels of thrombin-antithrombin complex (TAT), D-dimer, alpha2-plasmin inhibitor-plasmin complex (PIC), and fibrinogen were also evaluated.

RESULTS

The preoperative level of soluble FM-fibrinogen complex showed variation in the degree of hemostatic activation, with fair correlations with TAT (r = 0.509, P < .001), D-dimer (r = 0.521, P < .001), and PIC (r = 0.579, P < .001). The patients with greater intraoperative blood loss (> or = 800 mL) showed a significantly elevated plasma level of soluble FM-fibrinogen complex preoperatively compared with those with less intraoperative blood loss (P = .009). Its postoperative fluctuation showed a similar pattern to that of TAT, reflecting the time course of coagulation activity. Gelatin impregnation of the Dacron vascular graft did not seem to influence the postoperative systemic coagulation mechanism.

CONCLUSIONS

The results indicated that soluble FM-fibrinogen complex appears to be a useful diagnostic molecular marker to assess the activity of the coagulation system, and that its preoperative level may serve as a potential risk factor for intraoperative hemorrhagic diathesis in patients undergoing elective AAA repair.

Coagulopathy and Hyperfibrinolysis in Ruptured Abdominal Aortic Aneurysm Repair

Perioperative hemorrhage is one of the principal causes of death in patients with ruptured abdominal aortic aneurysm (AAA). This study examines perioperative coagulation and fibrinolysis in patients undergoing ruptured AAA repair complicated by coagulopathy. Eight patients (8 men of median age 74, range 69-87, years) who developed clinical and laboratory evidence of coagulopathy during attempted repair of ruptured infrarenal AAA were prospectively studied. Platelet count, fibrinogen, clotting times, prothrombin fragment (PF) 1+2, and tissue plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) activities were measured preoperatively, immediately before, and 5 min and 24 hr after aortic declamping. Six patients died, three intraoperatively, one within 24 hr, and two in the late postoperative period. All patients had thrombocytopenia and prolonged clotting times intraoperatively with evidence of increased thrombin generation (as demonstrated by elevated PF 1+2). Five patients had increased systemic fibrinolysis (as demonstrated by elevated t-PA activity) preoperatively and/or before aortic declamping and all of these patients died. Three patients had perioperative inhibition of systemic fibrinolysis (as demonstrated by elevated PAI activity) and two survived. These data demonstrate that coagulopathy in ruptured AAA repair may be associated with a hyperfibrinolytic state. Further research is required to determine if (a) a causal relationship exists between hyperfibrinolysis and coagulopathy and (b) whether antifibrinolytic agents can improve outcome if targeted at this group of patients.

Ruptured abdominal aortic aneurysm: endovascular treatment

BACKGROUND

This report describes our preliminary experience in endovascular management of 25 ruptured abdominal aortic aneurysms (rAAAs).

METHODS

In the past 3 years we treated 46 patients who had rAAA, and 25 (54.3%) were treated with an endovascular approach. Patients' mean age was 76 +/- 9 years. The diagnosis was confirmed by computed tomographic angiography in 23 patients (92%). Mean aneurysm diameter was 73 +/- 17 mm. We used an infrarenal bifurcated device in 17 patients (68%), a suprarenal bifurcated in four patients (16%), and an aortomonoiliac graft in four patients (16%). Overall, nine patients (36%) required intensive care. Every patient underwent radiologic follow-up according to the Eurostar register, with concomitant evaluation of the D-dimer level (cut-off <200 microg/L) as a biological marker for endoleaks.

RESULTS

The primary technical success rate was 100%. Overall in-hospital mortality rate was 20%. Mean hospitalization was 7 days (range, 3-30), and mean follow-up was 7 months. One occlusion (4%) of the iliac limb and two type II endoleaks (8%) occurred. The mean D-dimer level in type I endoleak was 1045 microg/L (range, 459-2021).

CONCLUSIONS

In our experience, endovascular management of rAAA is feasible and safe and produces better results than conventional surgery, provided the morphology is suitable and the procedure is carried out by an experienced endovascular team.