A randomised trial on modulating endogenous fibrinolysis in patients with acute coronary syndrome VaLiDate-R

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): This study is funded by Bayer PLC, 400 South Oak Way, Green Park, Reading, Berkshire, RG2 6AD.

Background

Impaired endogenous fibrinolysis is novel biomarker that can identify patients with ACS at increased cardiovascular risk. The addition of very low dose rivaroxaban (VLDR) to dual antiplatelet therapy has been shown to reduce cardiovascular events but at a cost of increased bleeding and is therefore not suitable for all-comers. Targeted additional pharmacotherapy with VLDR to improve endogenous fibrinolysis may improve outcomes in high-risk patients, whilst avoiding unnecessary bleeding in low-risk individuals.

Methods and Results

The VaLiDate-R study is an investigator-initiated, randomised, open-label, single centre trial comparing the effect of 3 antithrombotic regimens on endogenous fibrinolysis in 150 patients with ACS. Subjects whose screening blood test shows impaired fibrinolytic status (lysis time >2000s), will be randomised to one of 3 treatment arms in a 1:1:1 ratio: clopidogrel 75 mg daily (Group 1); clopidogrel 75 mg daily plus rivaroxaban 2.5 mg twice daily (Group 2); ticagrelor 90 mg twice daily (Group 3), in addition to aspirin 75 mg daily. Rivaroxaban will be given for 30 days. Fibrinolytic status will be assessed during admission and at 2, 4 and 8 weeks. The primary outcome measure is the change in fibrinolysis time from admission to 4 weeks follow-up, using the Global Thrombosis Test.

Conclusion

If VLDR can improve endogenous fibrinolysis in ACS, future large-scale studies would be required to assess whether targeted use of VLDR in patients with ACS and impaired fibrinolysis can translate into improved clinical outcomes, with reduction in major adverse cardiovascular events in this high-risk cohort.

Relationship between coronary stenosis severity and high shear thrombosis assessment in vitro

Funding Acknowledgements

Type of funding sources: None.

Among stable outpatients presenting with suspected coronary artery disease, the presence and extent of coronary artery calcification (CAC) and the severity of disease on CT coronary angiography (CTCA) has been shown to be predictive of future major adverse cardiovascular events (MACE) including myocardial infarction (MI). In stable patients, high on-treatment platelet reactivity has also been shown to relate to an increased risk of MACE including MI. The relationship between thrombotic markers in peripheral blood and the extent of CAC and coronary disease severity, is unknown.

It was the aim of this pilot study to assess the relationship between thrombotic status and the extent of CAC and severity of coronary stenosis on CT.

Subjects with suspected coronary disease undergoing CTCA and CAC were invited to participate in this observational study. Venous blood was obtained to assess platelet reactivity to high shear (occlusion time, OT) and endogenous fibrinolysis (lysis time, LT) using the Global Thrombosis Test, and related to CAC and to maximum stenosis in any main coronary artery on CTCA.

Eighty patients were recruited, specifically 20 patients from each CAC quartile (adjusted for age, gender and ethnicity), 58% were male, aged 61±10 y. Groups were matched for age, sex, diabetes, and hs-CRP. The median Agatson CAC score was 27 [interquartile range (IQR) 0.5-125.5] and in each quartile (Q) as follows: Q1 0[0-0]; Q2 17[6-51.5]; Q3 70.25[26-111.5] and Q4 192.6[70.5-413.5].

Patients were divided into 4 groups according to maximal severity of coronary stenosis on CTCA (0%, 1-49%, 50-69%, >70%). With increasing stenosis severity, we found patients exhibited less efficient endogenous fibrinolysis (longer LT) (LT 1728s[1512-2102] vs. 2028s[1687-2288] vs. 1728s[1634-1927] vs. 2524s[2425-2623] respectively, p=0.040) whilst platelet reactivity appeared unrelated to severity of coronary stenosis (438s[341-479] vs. 415s[357-484] vs. 444s[384-504] vs. 391s[357-425], p=0.907).

Platelet reactivity (OT 430s[339-477] vs. 458s[391-499] vs. 409s[351-488] vs. 413s[354-496], p=0.76) and spontaneous fibrinolysis (LT 1754s[1548-2162] vs. 1809s[1635-2291] vs. 2111s[1838-2312] vs. 1846s[1666-2090], p=0.253) were similar between the quartiles. Furthermore, there was no difference in platelet reactivity (430s[339-477] vs. 413s[354-496], p=0.830) or spontaneous fibrinolysis (1754s[1548-2162] vs. 1846s[1666-2090], p=0.561) when comparing patients within the lowest and the highest quartiles of CAC.

The severity of maximal coronary stenosis, but not the extent of CAC, is related to the effectiveness of spontaneous fibrinolysis at high shear in vitro, with patients with more severe stenoses exhibiting less efficient fibrinolysis. Further studies are required to investigate whether the extent of in vivo coronary shear (related to plaque morphology) can be reflected by the assessment of thrombosis and fibrinolysis in response to high shear in vitro.

Diurnal variation in thrombotic and fibrinolytic status in healthy volunteers

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): East and North Hertfordshire NHS Trust

Background

Previous studies assessing markers of fibrinolysis in healthy volunteers and patients with coronary artery disease (CAD) indicate circadian variation, primarily attributable to changes in plasminogen activator inhibitor-1 (PAI-1) concentrations, the main inhibitor of fibrinolysis, peaking between midnight and 06:00 hrs, with a nadir at 01:00 hrs. Whether the elevated PAI-1 translates into a global impairment of fibrinolysis, is not known.

Purpose

It was our aim to assess diurnal variation in global fibrinolytic activity in healthy subjects.

Methods

A single centre, prospective, observational study was conducted in healthy volunteers. Blood samples were obtained at two different time points on the same day, with a minimum inter-sample interval of 8 hours and a maximum of 12 hours. Venous blood was assessed to determine global thrombotic and fibrinolytic status in native whole blood status using the automated, point-of-care Global Thrombosis Test (GTT). This utilises non-anticoagulated blood to assess the time taken to form an occlusive thrombus under high shear (occlusion time) and the time taken for spontaneous restart of flow as a measure of endogenous fibrinolysis (lysis time).

Results

A total of 25 healthy volunteers (36% male), aged 34±12 y were included. All were non-smokers with a BMI of 25 (22.3 – 27.5) kg/m². The median interval between samples was 8:05 [hh:mm] (IQR 8:30 – 9:10). Occlusion time was similar in the morning and evening samples (median 451s [389 – 590] vs. 524s [428 – 597], p=0.207). Lysis time was also similar between morning and evening (median 1792s [1622 -2097] vs. 1726s [IQR 1517 – 1891], p=0.265).

Conclusion

Compared to the known circadian variation of thrombotic and fibrinolytic activity attributable to PAI-1, global thrombotic and fibrinolytic status do not appear to exhibit diurnal variation. Further studies are needed to assess how this correlates to t-PA and PAI-1 levels and the status in patients with cardiovascular disease.

Diurnal Variation in thrombolytic status in patients presenting with STEMI

Funding Acknowledgements

Type of funding sources: None.

Background

Prior studies mainly in healthy volunteers and patients with stable coronary artery disease (CAD) indicate circadian variation in spontaneous fibrinolytic activity. This is predominantly attributable to changes plasminogen activator inhibitor-1 (PAI-1) levels peaking between midnight and 06:00 hr, with a nadir at 18:00 hr. Whether circadian variation in spontaneous fibrinolysis exists amongst patients with ST-elevation myocardial infarction (STEMI) is unknown.

Purpose

It was our aim to assess circadian variation in fibrinolytic status in the acute setting in patients presenting with STEMI.

Methods

A prospective, observational study was conducted in patients presenting with STEMI for primary percutaneous coronary intervention (PPCI). Blood was tested on arrival pre-PPCI, after aspirin and P2Y12 inhibitor administration, but before any anticoagulant or antithrombotic agent administration in the cardiac cath lab. Venous blood was assessed to determine endogenous fibrinolysis using the Global Thrombosis Test, which utilises non-anticoagulated blood to assess the formation of an occlusive thrombus under high shear and the time taken for spontaneous restart of flow as a measure of endogenous fibrinolysis (lysis time, LT).

Results

A total of 527 patients were included, aged 64±13 years and 78% were male. 304 (58%) patients presented within working hours (08:00-17:00) with peak presentation between 11:00-12:00 and trough between 03:00 to 05:00 hrs.

Lysis time was not related to time of presentation. Time of presentation was divided into 4 groups (A 00:00-05:59, B 06:00-11:59, C 12:00-17:59, D 18:00-23:59 hrs). There was no significant difference in LT between patients presenting at the 4 timepoints (median 1362s [interquartile range IQR 1077-1808] vs 1503s [1182-2056] vs 1440s [1164-1998] vs. 1420s [1125-1820], respectively, p=0.340). When comparing Group A to C, the LT was not significantly different (1362s [1077-1808] vs. 1440 [1164-1998], p=0.413). The presentation time of patients with impaired endogenous fibrinolysis (LT>3000 sec) did not differ significantly from patients with normal endogenous fibrinolysis. The hourly variation was similar in diabetics and non-diabetics, but the variation in lysis time appeared blunted in patients taking long term aspirin prior to presentation compared to non-aspirin takers.

Conclusion

In contrast to the known circadian variation in fibrinolysis in normal volunteers, and stable CAD, in our large cohort of STEMI patients, there appears to be no relationship between time of presentation/onset of STEMI and the effectiveness spontaneous fibrinolysis. This is reflected in our observation, supported by most contemporary studies, that peak time of STEMI presentation is during the late morning, and this does not relate to known circadian variation in fibrinolysis markers in CAD.

Correlation between plasma clot properties, thrombin generation and whole blood fibrinolytic assays in patients presenting with STEMI

Background

Impaired endogenous fibrinolysis is a novel risk factor for recurrent adverse cardiovascular events in acute coronary syndrome (ACS) patients. This is independent of conventional cardiovascular risk factors and unaffected by dual antiplatelet therapy (DAPT). The mechanism underlying impaired endogenous fibrinolysis in ACS patients is currently unclear.

Aim

To identify the relationship between whole blood fibrinolysis, plasma fibrinolysis and thrombin generation in samples from STEMI patients.

Methods

In a large, prospective, observational study of 500 patients presenting with ST-segment elevation myocardial infarction (STEMI), blood samples were taken on arrival, after DAPT loading, and before administration of heparin or PPCI. Non-anticoagulated venous whole blood was analysed using the point-of-care Global Thrombosis Test, which assesses the time taken for occlusive thrombus formation under high shear (occlusion time, OT) and time required for spontaneous restart of flow as a measure of endogenous fibrinolysis (lysis time, LT). Patients were divided into 4 groups based on quartiles (Q) of whole blood LT (Q1: LT<1500s, Q2:1501–3000s, Q3:3001–4500s, Q4:>4500s). Plasma samples (20 per quartile) were examined in a thrombin generation assay using 1pM tissue factor to initiate and using a turbidity assay to determine the plasma clot lysis time (CLT).

Results

Clinical characteristics of patients were similar in the four groups. The whole blood LT in the 4 groups were Q1: 1194 (1125–1329) s, Q2: 1859 (1634–2157) s, Q3: 3638 (3252–3962) s, Q4: 6000 (5523–6000) s. As LT increased, there was a trend towards longer plasma CLT (50% CLT Q2: 88.5 [73.5–102] vs. Q4: 100 [85–128.5] min, p=0.088). As a continuous variable, there was no significant relationship between whole blood LT and plasma CLT, or between endogenous thrombin potential (ETP) and either whole blood LT or plasma CLT. There was a significant negative correlation between OT and velocity index (r=−0.425, p=0.0138), ETP (r=−0.519, p=0.002), peak thrombin generation (r=−0.390, p=0.0247) and a positive correlation with lag-time (r=0.427, p=0.013). There was positive correlation between CLT and white cell count (WCC, r=0.388, p=0.026), C-reactive protein (CRP, r=0.477, p=0.005) and maximum absorbance (MA, r=0.530, p=0.002). MA correlated with WCC (r=0.436, p=0.011) and platelet count (r=0.357, p=0.042). There was a negative correlation between OT and WCC (r=−0.537, p=0.001) and CRP (r=−0.381, p=0.029).

Conclusion

In patients with STEMI, increased platelet reactivity (shorter OT) correlated with increased thrombin generation (higher ETP, peak thrombin generation, velocity index and reduced lag time), demonstrating the key role of thrombin in occlusive thrombus formation. Fibrinolysis in whole blood was poorly related to plasma CLT or thrombin generation, suggesting that cellular components such as platelets, erythrocytes and neutrophil extracellular traps may significantly influence endogenous fibrinolysis.

Funding Acknowledgement

Type of funding source: None

Assessment of endogenous fibrinolysis using a point-of-care assay to identify increased cardiovascular risk in patients with diabetes and ACS

Introduction

Patients with diabetes mellitus (DM) are increased risk of myocardial infarction (MI) and following a MI, patients with DM have an increased risk of recurrent MI and cardiovascular (CV) death. Plasma turbidimetry studies show that hypofibrinolysis is a key abnormality in DM that may drive increased ischaemic risk. Such assays are cumbersome, require specialist expertise and do not provide information in a clinically-relevant timeframe. Assessment of fibrinolysis in whole blood, using a point-of-care assay, has revealed that in ACS patients, impaired fibrinolysis is predictive of adverse CV events. Whether this technique can identify residual risk in patients with DM, is unclear.

Purpose

It was our aim to compare thrombotic and endogenous fibrinolytic status between patients with and without DM, presenting with ACS.

Methods

We conducted a prospective, observational study of consecutive patients admitted with ACS. Venous blood was taken to assess thrombotic and thrombolytic status using the point-of-care Global Thrombosis Test, assessing time to occlusive thrombus formation under high shear (occlusion time, OT) and time taken for spontaneous lysis of the thrombus (lysis yime, LT). Blood was taken after dual antiplatelet therapy (DAPT) loading, but before administration of fondaparinux or low molecular weight heparin. Patients with renal or hepatic impairment, known bleeding diathesis, thrombocytopenia and those taking anticoagulation were excluded.

Results

A total of 775 patients were included, of whom 158 (20%) had DM. Patients with DM, compared to those without DM, more frequently had hypertension (70% vs. 39%, p<0.001), hyperlipidaemia (65% vs. 29%, p<0.001), higher BMI (28.6 [25.3–32.0] vs. 26.6 [23.7–29.8] kg/m2, p<0.001) and prior MI (28% vs 9%, p<0.001), but were less often smokers (23% vs. 34% p=0.007). In all other clinical characteristics DM and non-DM patients were matched. Time to occlusive thrombus formation was similar in patients with and without DM (OT 401 (284–519) s vs. 391 (289–514) s, p=0.603). There was a trend for longer LT in patients with DM compared to those without DM (LT 1634 (130–2321) s vs. 1562 (1247–2147) s, p=0.080). After propensity score matching to adjust for baseline differences in clinical characteristics, we observed a highly significant difference in LT between DM and non-DM patients (LT 1634 [1306–2321] s vs. 1387 [1109–1740] s, p<0.001). Patients with DM also had higher fibrinogen level (4.4 [3.5–5.4] vs. 4.1 [3.5–4.8] g/l, p=0.012) and higher C-reactive protein (5 [2–12] vs. 3 [1–8] mg/l, p=0.002). CRP correlated with LT (r=0.2, p=0.016), but no correlation was observed between fibrinogen and LT (r=0.069, p=0.424).

Conclusions

Amongst patients with ACS, those with DM exhibit markedly impaired endogenous fibrinolysis compared to those without DM, and this can be detected with a bedside assay using whole blood. This may explain the increased risk of secondary events in patients with ACS and DM.

Funding Acknowledgement

Type of funding source: None

No difference in thrombotic profile of patients with ACS with obstructive CAD and MINOCA

Introduction

Acute coronary syndrome (ACS) is caused by disruption of an atherosclerotic plaque with initiation of thrombosis, and outcome determined by the balance between prothrombotic drivers and the efficacy of endogenous fibrinolysis. Most patients have obstructive coronary artery disease (CAD), with high shear forces and turbulent flow across severe stenoses enhancing platelet activation. Recognition that some ACS patients have myocardial infarction (MI) with non-obstructive coronary arteries (MINOCA) has led to a search to identify drivers behind such presentations.

Purpose

To assess and compare the thrombotic status of patients with MINOCA and those with ACS due to obstructive CAD.

Methods

In a prospective observational study in patients with ACS, thrombotic and thrombolytic status was assessed from venous blood using the point-of-care Global Thrombosis Test, assessing time to in vitro occlusive thrombus formation under high shear (occlusion time,OT) and time taken for spontaneous lysis of the thrombus (lysis time,LT). Blood was taken after dual antiplatelet therapy loading, but before fondaparinux or heparin administration. Those with renal or hepatic impairment, bleeding diathesis, thrombocytopenia or on anticoagulation were excluded. MINOCA diagnosis was made according to the Fourth Universal Definition of MI, in the absence of obstructive CAD (no lesion ≥50%) and excluding patients with 1) other overt causes for elevated troponin, 2) overlooked obstructive CAD, and 3) nonischaemic causes for myocyte injury, according to the American Heart Association 2019 recommendation. Patients with Type 2, 4 and 5 MI were excluded.

Results

We assessed 746 patients, of whom 621 (83%) had ST-segment elevation MI (STEMI) and the rest non-STEMI. Of these, 706 (95%) had obstructive CAD and 40 (5%) had MINOCA. Apart from sex (78% obstructive CAD patients were male vs 50% MINOCA patients), cardiovascular risk factors were similar in MINOCA and obstructive CAD patients (smoking 28 vs 31%, p=0.615; hypertension 35 vs 47%, p=0.153; diabetes 20 vs 20%, p=0.948; hyperlipidaemia 30 vs 36%, p=0.475 and family history of premature CAD 35 vs 35%, p=1.000). There was no difference in time to form occlusive thrombus (OT 424 [371–471] vs 395 [287–512] s, p=0.093) or in endogenous fibrinolysis (LT 1450 [1082–2099] vs 1582 [1252–2130] s, p=0.178) between MINOCA and obstructive CAD patients. Even after propensity score matching with a ratio of 3:1 for clinical characteristics, there was no difference between patients with MINOCA and those with obstructive CAD, with respect to thrombus formation (OT 424 [371–471] vs 430 [300–538] s, p=0.602) or endogenous fibrinolysis (LT 1470 [1082- 2099] vs 1494 [1140–2074] s, p=0.625).

Conclusion

Amongst patients with ACS, those with MINOCA exhibit similar thrombotic profiles to patients with obstructive CAD with ACS. This represents a potential therapeutic target to modulate risk post myocardial infarction in patients with MINOCA and requires further research.

Funding Acknowledgement

Type of funding source: None

P4744Patients with atrial fibrillation exhibit a systemic prothrombotic state attributable to impaired endogenous fibrinolysis

Background

The association of atrial fibrillation (AF) with thromboembolic stroke due to stasis in the left atrium and left atrial appendage is well described. Whether AF is associated with a systemic prothrombotic state, detectable in peripheral blood, unclear. Previous studies have been inconsistent, with some very small previous studies (<30 patients each) variably indicating that patients with AF may have raised platelet reactivity and levels of antithrombin III, d-dimer, PAI-1 and t-PA-PAI complexes. These cumbersome laboratory tests of coagulation and fibrinolysis are not readily available in the clinical setting.

Purpose

It was our aim to compare, in peripheral venous blood, thrombotic and endogenous fibrinolytic profile of healthy volunteers and patients with newly diagnosed nonvalvular atrial fibrillation (NVAF), using a point-of-care technique.

Methods

In a prospective observational study, venous blood samples were taken from 98 healthy volunteers and 100 patients with newly diagnosed NVAF in the out-patient setting. Patients with newly diagnosed NVAF had venous blood tested before any treatment was initiated with aspirin or oral anticoagulation. Thrombotic status was assessed using the Global Thrombosis Test (GTT), a point-of-care test using native non-coagulated blood, assessed within 15 sec of blood withdrawal. The time to form an occlusive venous thrombus in native (non-citrated) blood, a measure of platelet reactivity (occlusion time, OT) and the time taken to spontaneous endogenous fibrinolysis to restore flow (lysis time, LT) were assessed.

Results

Basic blood tests (full blood count, renal and liver function, inflammatory markers) were normal in all subjects. The groups were matched for sex and race. Mean age of the healthy cohort was 34±8 years and patients 65±10 years.

Endogenous fibrinolysis was markedly impaired in patients with NVAF compared to healthy individuals as shown by markedly prolonged LT (median 2015s [interquartile range IQR 1555–2507] vs. 1124s [IQR 919–1554], p<0.ehz745.11201). There was no difference in platelet reactivity between patients and normal volunteers (369s [IQR 308–445]vs 368s [IQR 309–441], p=0.704). Sensitivity analysis was performed on a subgroup matched for age, sex and race. LT remained significantly longer in patients with NVAF compared to controls (1569s [IQR 1499–2244] vs. 1219s [IQR 943–1560], p=0.03), with no difference in platelet reactivity (p=NS).

Conclusion

In the largest study to date and using a clinically-friendly automated point-of-care technique, we show that patients with NVAF exhibit a systemic prothrombotic state, attributable to significantly impaired endogenous fibrinolysis compared with healthy volunteers. Further studies are needed to see if this could become a screening test for the prothrombotic state in patients with NVAF.

Acknowledgement/Funding

None

Endogenous thrombin potential and examination of a further 31 analytes in liver transplant candidates

BACKGROUND

To predict the change in patient status and differentation of the basic diseases, endogenous thrombin potential (ETP), clinical chemistry, and coagulation variables were measured in liver transplant-listed patients with different etiologies.

METHODS

Differences in values of ETP and analytes of 30 control persons and 164 cirrhotic patients were examined by means of binary logistic regression. The relationship between the analytes and ETP parameters were analyzed by means of Spearman correlation. The different etiologies of cirrhosises were studied by factor and discriminant analyses. Binary logistic regression was applied to forecast changes in clinical status. Survival analysis was carried out with the appropriate variable.

RESULTS

International Normalized Ratio and activated partial thromboplastin time values were higher, whereas the area-under-the-curve values were lower in cirrhosis than in healthy subjects. A strong relationship was found only between the peak height and the anti-thrombin III (ATIII) values. In the factor analysis, 3 factors were found, which explained 81.6% of the total variance. Combination of aspartate aminotransferase and ATIII mostly separated the basic disease groups from each other in the discriminant analysis. From 35 variables, the lactate dehydrogenase (LDH) and ATIII have been suited for predicting the change in patient status. Eighty percent of patients with low ATIII and high LDH levels had deterioration of their clinical status.

CONCLUSIONS

Our study demonstrated that the ETP parameters did not provide additional information compared with "conventional" coagulation tests in cirrhosis. On the basis of our study, LDH and ATIII appear to be promising analytes to assess the clinical status of patients with cirrhosis. In our opinion, the classification system of liver transplant-listed patients can be improved with their use.

Significance of mycophenolate monitoring in liver transplant recipients: toward the cut-off level

Mycophenolate mofetil blocks the "de novo" -purine synthesis to reduce the incidence and severity of acute rejection episodes. There has been an increased interest in utility of monitoring mycophenolic acid (MPA) levels, however currently the MPA monitoring is not part of the protocol following liver transplantation. We assessed whether trough MPA monitoring could be advisable in liver transplant patients or not. For this reason MPA levels of 56 liver transplants were measured on 3, 5, 10, 14, 21, 30, 60, and 180 posttransplant days. The optimal cut-off of MPA level (≥1.73 mg/L) for all (56) and ≥1.34 mg/L for ciclosporin-treated- and ≥1.98 mg/L for the tacrolimus-treated transplants were calculated by statistical analysis to reduce the incidence of acute rejection. MPA concentrations of 3 days period before the day of clinical diagnosis acute rejection were well below the cut-off value. Only 3 (16%) out 19 patients with acute rejection had higher MPA levels than the cut-off value on the day of diagnosis of acute rejection. In conclusion, our data suggests that MPA predose level monitoring, especially in the early "filling phase" after transplantation, is applicable in liver allograft recipients given adjunctive MMF, protecting them from the ineffective immunosuppression.

Small difference in international normalized ratio may yield a significant impact on prioritizing patients listed for liver transplantation

Priority for liver transplantation is currently based on the Model for End-stage Liver Disease (MELD) score. The aim of our study was to assess in detail the contribution of international normalized ratio (INR) differences for MELD scores because of interlaboratory variability. The samples from 92 cirrhotic patients were measured on different systems combining three coagulometers and three thromboplastin products to determine variations in INR and MELD score. The INR differences among the first four systems varied between 0 and 0.2, resulting in MELD differences of 0 to 2. The MELD scores of 92 patients changed only among 10 possible integers so that normally 2 to 10 patients shared the same MELD value. In some cases, one MELD score difference resulted in a 10 superpositioning on the waiting list. Including one more system (mechanical vs optical) into our investigations achieved a five MELD difference. Supposing an extreme situation where one patient competes with his or her lowest, all the other with their highest possible score (and visa versa), the difference may be even 20 positions, overturning the complete waiting list. In conclusion substantial interlaboratory differences in MELD score have profound clinical consequences.

Vasomotor responses of coronary stenoses to acetylcholine and their relation to serum lipid levels in stable angina pectoris

The effects of acetylcholine administration on coronary stenoses in relation to serum lipids level were evaluated in 18 patients (15 men, 3 women) with coronary artery disease and stable angina. Intracoronary acetylcholine was infused in concentrations 10(-7), 10(-6), 10(-5) M, followed by intracoronary bolus administration of isosorbide dinitrate. Computerized angiography was used to assess the changes in the diameter of stenoses and of proximal and distal segments. During acetylcholine infusion, at concentrations between 10(-7) to 10(-5) M, there was a significant (p <0.01) dose-dependent constriction of proximal and distal segments and of stenoses reversed by isosorbide dinitrate. There was no correlation between the serum total cholesterol level and the responses of proximal and distal segments to acetylcholine or nitrate. A correlation (p <0.05) was found between the serum total cholesterol level and the response of stenoses to acetylcholine, but there was no correlation with the response to isosorbide dinitrate. In conclusion, in patients with stable angina current serum total cholesterol level correlates with the vasomotor response of coronary stenoses to intracoronary acetylcholine. These findings are consistent with a direct effect of cholesterol, increasing basal coronary vasomotor tone and increasing the stimulated vasoconstrictor response of stenoses.