Relationship between endothelin-1, heart failure with reduced ejection fraction and dapagliflozin: findings from DAPA-HF

Background

Circulating Endothelin-1 (ET-1) is associated with heart failure (HF) severity and has also been widely implicated in the pathophysiology of renal disease. However, its prognostic importance and relationship with kidney function in patients with HFrEF receiving contemporary treatment is uncertain.

Purpose

To investigate the association of ET-1 with heart failure outcomes, as well as change in kidney function; and the efficacy of dapagliflozin according to baseline serum ET-1 in the Dapagliflozin And Prevention of Adverse outcomes in Heart Failure trial (DAPA-HF).

Methods

Serum ET-1 was measured at randomization and at 12 months and analysed using a Microfluidics immunoassay. We investigated the incidence of the primary outcome (cardiovascular death or worsening HF), and analysed change in kidney function according to tertile of baseline ET-1 concentration. Additionally, we assessed whether baseline ET-1 modified the treatment effect of dapagliflozin.

Results

Of 4744 randomized participants, 3048 (64.2%) had a baseline ET-1 measurement: tertile 1 (≤3.28 pg/mL, n=1016), tertile 2 (>3.28 to 4.41 pg/mL, n=1022), and tertile 3 (>4.41 pg/mL, n=1010). Patients with higher baseline ET-1 concentrations were more likely male, obese and to have lower LVEF, lower eGFR, worse functional status, and elevated NT-proBNP and high-sensitivity troponin-T.

Adjusting for other predictive variables including NT-proBNP, higher baseline ET-1 was independently associated with worse outcomes and steeper decline in kidney function: adjusted hazard ratio (aHR) for the primary outcome of 1.95 (1.53–2.50) for tertile 3 and 1.36 (95% CI 1.06–1.75) for tertile 2; aHR for worsening HF of 2.54 (1.82–3.53) for tertile 3 and 1.54 (1.10–2.18) for tertile 2; aHR for cardiovascular death of 1.39 (1.01–1.92) for tertile 3 and 1.13 (0.82–1.57) for tertile 2; and eGFR slope −3.19 (95% CI −3.66 to −2.72) mL/min/1.73 m2 per year in tertile 3 versus −2.06 (−2.51 to −1.62) in tertile 2 and −2.35 (−2.79 to −1.91) in tertile 1, p for difference (eGFR slope)=0.002.

The benefit of dapagliflozin was consistent regardless of baseline ET-1, whether analysed according to tertiles or as a continuous variable, with p-interaction for primary outcome 0.47 and 0.10 respectively. Compared to placebo, there was a trend to reduction in ET-1 level at 12 months with dapagliflozin (difference −0.12 pg/mL, p-value=0.07).

Conclusions

Baseline ET-1 concentration was independently associated with clinical outcomes and with more rapid decline in kidney function. The benefit of dapagliflozin was consistent across the range of ET-1 concentrations measured.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): The DAPA-HF trial was funded by AstraZeneca. Professor John McMurray is supported by a British Heart Foundation Centre of Research Excellence Grant RE/18/6/34217.

The relative importance of particle count, type, and size of ApoB-containing lipoproteins in risk of myocardial infarction

Background

An accumulating body of evidence suggests that the number of apolipoprotein B-containing particles (ApoB-P) is more predictive of cardiovascular risk than their lipid content. However, it is unclear if this association is consistent across different lipoprotein types and sizes.

Purpose

We aimed to evaluate if particle type and size are associated with incident myocardial infarction (MI) beyond ApoB-P count. Moreover, we aimed to determine if the risk associated with lipoprotein(a) is additive to that of ApoB-P.

Methods

This prospective cohort study included 96,126 participants without prior history of stroke, coronary or peripheral artery disease or use of lipid-lowering medication from the UK Biobank. Count and size of VLDL, IDL, LDL, and HDL, as well as ApoB level and total ApoB-P count were measured in non-fasting plasma samples by nuclear magnetic resonance platform. Lipoprotein(a) was measured by immunoturbidimetric assay. We explored associations between these lipoprotein markers and incident MI using Cox proportional hazard models adjusted sequentially for clinical covariates, HDL count and size, and ApoB-P.

Results

Over a median follow-up of 12.1 years, 1702 participants had incident MI. In unadjusted models, 1-SD increases in ApoB-P count, ratio of VLDL to (LDL+IDL) particle counts, VLDL size and lipoprotein(a) were associated with a higher risk of MI, while LDL size was associated with a lower risk of MI (Table 1). When adjusting for clinical covariates and lipid parameters, only ApoB-P and lipoprotein(a) remained significantly associated with a higher risk of MI (HR: 1.40 [1.32; 1.48] and 1.20 [1.14; 1.27], respectively). Adjusted restricted cubic splines confirmed findings from linear trend Cox models (Figure 1). ApoB-P count was highly correlated with ApoB level (r=0.99), and replication of analyses replacing one for another revealed no change in results.

Conclusion

The risk of MI is independently associated with the total particle count of all ApoB-P, and not the size or type of these lipoproteins. ApoB level can be used as a very accurate surrogate of ApoB-P count in the clinical setting. Lipoprotein(a) is associated with MI risk independently of total particle count, and therefore, the combination of ApoB and lipoprotein(a) may provide the optimal clinical evaluation of lipid-mediated MI risk.

Funding Acknowledgement

Type of funding sources: None.

Outcomes related to IGFBP-7 in patients with heart failure and reduced ejection fraction and effects of dapagliflozin: findings from DAPA-HF

Introduction

Insulin-like growth factor binding protein 7 (IGFBP-7) has been proposed as a novel prognostic biomarker in heart failure, but the association between IGFBP-7 and cardiovascular outcomes has not been examined in a large cohort of patients with heart failure and reduced ejection fraction (HFrEF).

Purpose

In this post-hoc analysis of the Dapagliflozin And Prevention of Adverse outcomes in Heart Failure trial (DAPA-HF) we examined the relationship between plasma IGFBP-7 level and outcomes in patients with HFrEF, the effect of dapagliflozin according to IGFBP-7 level and change in IGFBP-7 at 12 months.

Methods

Patients in NYHA class II–IV with LVEF ≤40% and elevated NT-proBNP were included in DAPA-HF. Participants were randomly allocated to dapagliflozin 10mg or matching placebo. In this analysis, patients were categorized by IGFBP-7 tertile. The primary outcome was a composite of cardiovascular death or worsening HF event; secondary outcomes were components of the primary outcome and all-cause mortality. The risk of each outcome was compared across thirds of IGFBP-7 using Cox regression models with adjustment for NT-proBNP and high-sensitivity troponin T as well as: randomised treatment, age, sex, race, region, systolic blood pressure, heart rate, ejection fraction, estimated glomerular filtration rate, NYHA class, history of HF hospitalisation, ischaemic aetiology of HF, hypertension, stroke, atrial fibrillation, prior MI and stratified by diabetes status. The efficacy of dapagliflozin was assessed according to baseline IGFBP-7 level. Change in IGFBP-7 at 12 months was assessed using the ratio of geometric means.

Results

3158 patients had measurement of IGFBP-7 at baseline. The median value of IGFBP-7 was 192 ng/mL (interquartile range 158–246). Patients in the highest third of IGFBP-7 levels had more advanced HF, with higher NYHA class and NT-proBNP, had worse renal function and more type 2 diabetes. Patients in the highest third had the highest rate of the primary outcome (Figure 1). The adjusted hazard ratio (aHR) for the primary endpoint (with lowest third of IGFBP-7 as reference) was 0.94 (95% CI 0.74–1.20) for middle third and 1.49 (95% CI 1.17–1.89) for top third. The corresponding aHRs for worsening HF event were 0.99 (95% CI 0.72–1.36) for middle third and 1.84 (95% CI 1.35–2.50) for top third. Cardiovascular and all-cause mortality did not vary by IGFBP-7 tertile. The benefit of dapagliflozin was consistent regardless of baseline IGFBP-7 (p for interaction for primary endpoint = 0.34). The change in IGFBP-7 from baseline to 12 months did not differ between placebo and dapagliflozin.

Conclusions

Elevation of IGFBP-7 in patients with HFrEF was associated with more adverse HF outcomes, even after adjustment for both NT-proBNP and hsTnT. The treatment benefit of dapagliflozin did not vary by baseline IGFBP-7.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The DAPA-HF trial was funded by AstraZeneca.CA and JJVM are supported by a British Heart Foundation Centre of Research Excellence Grant.

Stroke in patients with heart failure and reduced ejection fraction without atrial fibrillation: external validation of a risk model

Background

Heart failure (HF) ranks only second to atrial fibrillation (AF) as a cause of cardio-embolic stroke. Although anticoagulation reduces this risk in HF patients not in AF, the risk/benefit profile in relatively unselected populations is not favourable. Identification of patients at high risk of stroke may allow targeted and safer use of prophylactic anticoagulant therapy. Previously, we proposed a simple risk model for stroke in patients with HF and reduced ejection fraction (HFrEF). However, this model was derived from the two older trials (published in 2007/2008) and was not externally validated.

Purpose

We aimed to evaluate the current incidence of stroke in patients with HFrEF not in AF receiving modern pharmacological therapy and to validate our stroke prediction model.

Methods

We examined patient-level data from the PARADIGM-HF, ATMOSPHERE, and DAPA-HF trials. The risk score was calculated following: 7.39×(insulin-treated diabetes) + 6.53×(previous stroke) + 2.80×[ln(NT-proBNP (pg/ml)) × 0.1182]). According to the tertile of risk score, we divided the patients into three groups. Patients with AF were defined as those with either AF on an ECG or a history of AF.

Results

Of the total of 20,159 patients (who experienced 590 strokes) enrolled in the three trials, 12,751 patients did not have AF at baseline. Of those, 1,143 patients (9%) had insulin-treated diabetes, 873 patients (6.8%) had a history of the previous stroke, and the median value of NT-proBNP was 1,243 pg/ml. During a median follow-up of 2.0 years, 346 (2.7%) experienced a stroke (11.7 per 1000 patient-years). Figure 1 shows cumulative incidence function plots for stroke according to the tertile of risk score in 12,331 patients whose risk score can be calculated. The number of strokes in tertile 1, 2 and 3 were 80, 102 and 149, respectively. The 3-year cumulative incidence function rates of stroke were 2.0 (95% CI: 1.5–2.5) % in tertile 1, 2.6 (95% CI: 2.1–3.2) % in tertile 2, and 4.3 (95% CI: 3.6–5.2) % in tertile 3, respectively. In patients with tertile 3, the stroke rate was 18.1 per 1000 patient-years (compared to 20.1 per 1000 patient-years in patients with AF not receiving anticoagulation). In the Cox model, risk for stroke increased according to the elevation in the risk score (tertile 2: HR 1.47 (95% CI 1.09–1.97), tertile 3: HR 2.53 (95% CI 1.92–3.33), with tertile 1 as reference). Figure 2 shows calibration plots by comparing observed and predicted probabilities of stroke at 1 to 3 years. Discrimination evaluated using the overall c-index 0.84 (95% CI: 0.75–0.91) was good.

Conclusions

These findings validate a previously described predictive model and confirm that it is possible to identify a subset of HFrEF patients without AF who have a risk of stroke that approximates to that in patients with AF. In these patients, the risk/benefit balance might justify the use of prophylactic anticoagulation, but this hypothesis needs to be tested prospectively.

Funding Acknowledgement

Type of funding sources: Foundation.

Cardiovascular benefit of lowering LDL-C below 1 mmol/L (40 mg/dl)

Background

The 2019 ESC/EAS Dyslipidemia Guidelines recommend an LDL-C goal of <1.4 mmol/L (∼55 mg/dl) for patients with very high-risk ASCVD, and <1 mmol/L (∼40 mg/dl) for those with recurrent events within 2 years despite taking maximally tolerated statin therapy. The addition of PCSK9 inhibitors to statin therapy can achieve LDL-C levels well below 1 mmol/L in many patients, yet the clinical benefit of LDL-C lowering beyond this level has recently been questioned.

Methods

FOURIER was a cardiovascular outcomes trial comparing evolocumab vs. placebo in patients with stable ASCVD on optimized statin therapy with a median follow-up of 2.2 years. We performed an exploratory analysis to determine the consistency of CV risk reduction with LDL-C lowering below ∼1 mmol/L (40 mg/dl) with evolocumab. We modeled the achieved LDL-C at 48 weeks in the two treatment arms as well as the percentage of LDL-C difference between the two arms that was due to LDL-C below ∼1 mmol/L (40 mg/dl) as a function of baseline LDL-C. We then modeled the hazard ratio (HR) for the composite of CV death, MI or stroke (per 1 mmol/L reduction in LDL-C) with evolocumab vs. placebo as a function of baseline LDL-C.

Results

All 27,564 patients from FOURIER were included in this analysis. Patients with lower baseline LDL-C achieved lower LDL-C levels following evolocumab therapy, with achieved LDL-C typically being below 1 mmol/L (40 mg/dl) once the baseline LDL-C was below 2.4 mmol/L (94 mg/dl) and reaching levels approaching 0.5 mmol/L (∼20 mg/dl). Accordingly, the further baseline LDL-C levels were below 2.4 mmol/L (94 mg/dl), the greater the proportion of the difference in achieved LDL-C between the evolocumab and placebo arms was due to LDL-C levels below ∼1 mmol/L (40 mg/dl), reaching nearly 40% of the difference in LDL-C between treatment arms (Upper Panel). Despite this, the clinical benefit of LDL-C lowering was not attenuated (p=0.78) (and even appeared greater), with robust reductions in risk of CV death, MI or stroke even when LDL-C was lowered to nearly 0.5 mmol/L (∼20 mg/dl) and having close to 40% of the LDL-C difference between treatment arms due to LDL-C lowering below ∼1 mmol/L (40 mg/dl) (Lower Panel).

Conclusion

PCSK9 inhibitors added to statin therapy can achieve LDL-C well below 1 mmol/L (40 mg/dl). There is no evidence for attenuation of the clinical benefit of lowering LDL-C below this threshold. These data support lowering LDL-C to below 1 mmol/L (40 mg/dl) in patients with ASCVD.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Institute of Health

192Effect of dapagliflozin on cardiovascular outcomes in patients with type 2 diabetes according to baseline renal function and albuminuria status: Insights from DECLARE-TIMI 58

Background

Renal dysfunction including both reduced estimated glomerular filtration rate (eGFR) and the presence of albuminuria have each been shown to predict cardiovascular (CV) outcomes. Sodium glucose co-transporter 2 inhibitors (SGLT2i), which promote glucose excretion in the kidneys, reduce CV events and hospitalizations for heart failure (HHF) in patients with type 2 diabetes mellitus (T2DM).

Purpose

To analyze the CV efficacy of dapagliflozin according to baseline renal function and albuminuria status in DECLARE-TIMI 58.

Methods

The DECLARE-TIMI 58 trial compared dapagliflozin vs. placebo in 17,160 patients with T2DM and a creatinine clearance >60 ml/min/1.73m2 at enrollment. The dual primary endpoints were CV death/HHF and MACE (MI, stroke, CV death). We categorized patients according baseline eGFR [<60 vs. ≥60 ml/min/1.73m2 according to the CKD-EPI formula] and urinary albumin:creatinine ratio (UACR) [<30 vs. ≥30 mg/g]. Cox regression models with interaction testing were applied. The Gail-Simon test was used to test for interaction of the absolute risk differences.

Results

In total, 5198 (30.3%) patients had albuminuria (UACR 30–300: n=4029; UACR >300: n=1169) and 1265 (7.4%) had an eGFR <60 ml/min/1.73m2. Accordingly, 10958 (63.9%) patients had no manifestation of CKD, 5367 (31.3%) had either an eGFR <60 ml/min/1.73m2 or albuminuria, and 548 (3.2%) patients had both manifestations. Patients with more abnormal markers had higher event rates for CV death/HHF (KM event rates at 4 years of 3.9%, 8.3%, 17.4%) and MACE (7.5%, 11.7%, and 18.9%) for no, 1, or 2 markers of CKD, respectively. The relative risk reductions for CV death/HHF and MACE were generally consistent across the subgroups (both P-interaction >0.29), though numerically greatest (42%) in patients with reduced eGFR and albuminuria. However, the absolute risk difference increased substantially in patients with greater kidney damage (absolute risk difference of CV death/HHF: −0.5%, −1.0%, and −8.3%, respectively; P-INT for ARD 0.002; Figure). See figure for MACE and component outcomes.

Conclusions

Patients with baseline renal disease had higher rates of adverse CV outcomes. Dapagliflozin reduced events with generally consistent relative risk, but reduced the absolute risk of CVD/HHF by the greatest amount in patients with kidney disease evidenced by both reduced eGFR and albuminuria.

Acknowledgement/Funding

AstraZeneca, Deutsche Forschungsgemeinschaft (ZE 1109/1-1)

Genetic risk, coronary heart disease events, and the clinical benefit of statin therapy: an analysis of primary and secondary prevention trials

BACKGROUND

Genetic variants have been associated with the risk of coronary heart disease. In this study, we tested whether or not a composite of these variants could ascertain the risk of both incident and recurrent coronary heart disease events and identify those individuals who derive greater clinical benefit from statin therapy.

METHODS

A community-based cohort study (the Malmo Diet and Cancer Study) and four randomised controlled trials of both primary prevention (JUPITER and ASCOT) and secondary prevention (CARE and PROVE IT-TIMI 22) with statin therapy, comprising a total of 48,421 individuals and 3477 events, were included in these analyses. We studied the association of a genetic risk score based on 27 genetic variants with incident or recurrent coronary heart disease, adjusting for traditional clinical risk factors. We then investigated the relative and absolute risk reductions in coronary heart disease events with statin therapy stratified by genetic risk. We combined data from the different studies using a meta-analysis.

FINDINGS

When individuals were divided into low (quintile 1), intermediate (quintiles 2-4), and high (quintile 5) genetic risk categories, a significant gradient in risk for incident or recurrent coronary heart disease was shown. Compared with the low genetic risk category, the multivariable-adjusted hazard ratio for coronary heart disease for the intermediate genetic risk category was 1·34 (95% CI 1·22-1·47, p<0·0001) and that for the high genetic risk category was 1·72 (1·55-1·92, p<0·0001). In terms of the benefit of statin therapy in the four randomised trials, we noted a significant gradient (p=0·0277) of increasing relative risk reductions across the low (13%), intermediate (29%), and high (48%) genetic risk categories. Similarly, we noted greater absolute risk reductions in those individuals in higher genetic risk categories (p=0·0101), resulting in a roughly threefold decrease in the number needed to treat to prevent one coronary heart disease event in the primary prevention trials. Specifically, in the primary prevention trials, the number needed to treat to prevent one such event in 10 years was 66 in people at low genetic risk, 42 in those at intermediate genetic risk, and 25 in those at high genetic risk in JUPITER, and 57, 47, and 20, respectively, in ASCOT.

INTERPRETATION

A genetic risk score identified individuals at increased risk for both incident and recurrent coronary heart disease events. People with the highest burden of genetic risk derived the largest relative and absolute clinical benefit from statin therapy.

FUNDING

National Institutes of Health.

Clinical Pharmacogenetics Implementation Consortium guidelines for CYP2C19 genotype and clopidogrel therapy: 2013 update

Cytochrome P450 (CYP)2C19 catalyzes the bioactivation of the antiplatelet prodrug clopidogrel, and CYP2C19 loss-of-function alleles impair formation of active metabolites, resulting in reduced platelet inhibition. In addition, CYP2C19 loss-of-function alleles confer increased risks for serious adverse cardiovascular (CV) events among clopidogrel-treated patients with acute coronary syndromes (ACSs) undergoing percutaneous coronary intervention (PCI). Guideline updates include emphasis on appropriate indication for CYP2C19 genotype-directed antiplatelet therapy, refined recommendations for specific CYP2C19 alleles, and additional evidence from an expanded literature review (updates at http://www.pharmgkb.org).

The management of unstable angina and non-ST-segment elevation myocardial infartion

Patients presenting with unstable angina and non-ST elevation myocardial infarction (UA/NSTEM) have a highly variable course. Optimal management is critical because of the high risk of death or myocardial infarction (MI) in the ensuing 30 days. In this article, we review the therapeutic options available to clinicians. Anti-ischemic therapy with beta-blockers and nitrates should be considered in all patients without contraindications. Aspirin remains a cornerstone of antiplatelet therapy and has been shown to substantially reduce the risk of death or MI. Although the data are less robust, unfractionated heparin (UFH) also appears to be efficacious, and the low-molecular-weight heparin (LMWH) enoxaparin appears to be superior to UFH. The GP IIb/IIIa inhibitors, highly beneficial in the setting of percutaneous coronary intervention (PCI), should be considered in patients with continuing ischemia or other high-risk features. The ADP receptor blocker clopidogrel has been shown to be beneficial in patients who are managed conservatively and in those who undergo PCI. Lastly, a strategy of early angiography should be considered in patients with recurrent ischemia or in those who present with high-risk features such as elevated troponins or ST deviation. Thus, early risk stratification using clinical features, electrocardiographic data, and biomarkers allows identification of subgroups of patients who are not only at high risk but also enjoy the greatest benefits from these aggressive therapies and thereby enables clinicians to target these interventions most effectively.

The prognostic value of B-type natriuretic peptide in patients with acute coronary syndromes

BACKGROUND

Brain (B-type) natriuretic peptide is a neurohormone synthesized predominantly in ventricular myocardium. Although the circulating level of this neurohormone has been shown to provide independent prognostic information in patients with transmural myocardial infarction, few data are available for patients with acute coronary syndromes in the absence of ST-segment elevation.

METHODS

We measured B-type natriuretic peptide in plasma specimens obtained a mean (+/-SD) of 40+/-20 hours after the onset of ischemic symptoms in 2525 patients from the Orbofiban in Patients with Unstable Coronary Syndromes-Thrombolysis in Myocardial Infarction 16 study.

RESULTS

The base-line level of B-type natriuretic peptide was correlated with the risk of death, heart failure, and myocardial infarction at 30 days and 10 months. The unadjusted rate of death increased in a stepwise fashion among patients in increasing quartiles of base-line B-type natriuretic peptide levels (P< 0.001). This association remained significant in subgroups of patients who had myocardial infarction with ST-segment elevation (P=0.02), patients who had myocardial infarction without ST-segment elevation (P<0.001), and patients who had unstable angina (P<0.001). After adjustment for independent predictors of the long-term risk of death, the odds ratios for death at 10 months in the second, third, and fourth quartiles of B-type natriuretic peptide were 3.8 (95 percent confidence interval, 1.1 to 13.3), 4.0 (95 percent confidence interval, 1.2 to 13.7), and 5.8 (95 percent confidence interval, 1.7 to 19.7). The level of B-type natriuretic peptide was also associated with the risk of new or recurrent myocardial infarction (P=0.01) and new or worsening heart failure (P<0.001) at 10 months.

CONCLUSIONS

A single measurement of B-type natriuretic peptide, obtained in the first few days after the onset of ischemic symptoms, provides powerful information for use in risk stratification across the spectrum of acute coronary syndromes. This finding suggests that cardiac neurohormonal activation may be a unifying feature among patients at high risk for death after acute coronary syndromes.

A risk score system for predicting adverse outcomes and magnitude of benefit with glycoprotein IIb/IIIa inhibitor therapy in patients with unstable angina pectoris

Clinical outcomes of patients with unstable angina are variable. We sought to identify predictors of adverse clinical outcomes in patients with unstable angina and to investigate whether these factors would predict the magnitude of benefit achieved with platelet glycoprotein IIb/IIIa inhibition. We analyzed 20 variables in the 1,915 patients enrolled in the Platelet Receptor Inhibition for Ischemic Syndrome Management in Patients Limited by Unstable Signs and Symptoms trial. Five independent predictors were identified: age >65 years, prior coronary artery bypass grafting, antecedent aspirin use, antecedent beta-blocker use, and ST depressions on the presenting electrocardiogram. A risk score system was created using these predictors in which patients were assigned 1 point for the presence of each risk factor. There was a progressive increase in the rate of the composite end point of death, myocardial infarction, or refractory ischemia at 7 days with an increasing number of risk factors. For patients treated with heparin alone, the composite end point event rate was 6.5% in the group with 0 or 1 predictor, 14.6% in the group with 2 predictors, 22.7% in the group with 3 predictors, and 37.1% in the group with 4 or 5 predictors (p <0.00001). When dividing patients into low- (0 or 1 point), medium- (2 or 3 points), and high-risk (4 or 5 points) groups, the addition of tirofiban to heparin therapy was associated with no significant benefit in the low-risk group, a 5.2% absolute reduction in the medium-risk group (p = 0.05), and a 16% absolute reduction in the high-risk group (p = 0.0055). Thus, we have developed a risk score system using 5 variables that can be used to identify patients at high risk for death and cardiac ischemic events and who experience the greatest benefit from the addition of a glycoprotein IIb/IIIa inhibitor to their treatment regimen.

Elevation in serum troponin I predicts the benefit of tirofiban

BACKGROUND

Elevations in serum troponins among patients with acute coronary syndromes have been shown to identify those patients who are at high risk for poor outcome and who accrue larger relative benefits from aggressive antiplatelet and antithrombotic therapies. We studied a group of patients from the PRISM-PLUS trial to explore whether simply using serum troponin I, a serum marker of cardiac injury, could predict benefit of GP IIb/IIIa receptor antagonism with tirofiban.

METHODS AND RESULTS

For this study, the subjects consisted of 55 patients receiving the combination therapy of tirofiban/heparin, and 55 receiving heparin alone. The baseline characteristics were similar between the two treatment groups. Serial blood samples were obtained over the first 24-hour period following randomization to study drug, and were analyzed for troponin I (TnI) levels. Among those patients with elevated serum TnI (>0.5 ng/ml), the 30-day event rate for death or myocardial infarction (MI) was reduced from 20.6% among the heparin only group to 3.6% for those treated with the combination of tirofiban/heparin, an absolute risk reduction of 17% and relative risk reduction of 83% (p=0.06). Among the TnI negative patients, the rates of death/MI at 30 days were 9.5% and 11.1% among the combination and heparin treated groups respectively (p=NS).

CONCLUSION

Irrespective of high-risk clinical factors, including ST segment depression, these data support the hypothesis that serum troponins identify those who benefit from aggressive antiplatelet therapy with tirofiban.

Combination of a direct thrombin inhibitor and a platelet glycoprotein IIb/IIIa blocking peptide facilitates and maintains reperfusion of platelet-rich thrombus with alteplase

We sought to determine the efficacy of the combination of argatroban, a direct thrombin inhibitor, and G4120, a platelet glycoprotein (GP) IIb/IIIa blocker, to enhance thrombolysis with alteplase. Platelet-rich thrombus in the rabbit arterial thrombosis model is relatively resistant to alteplase despite the addition of aspirin and heparin. The adjunctive use of either direct thrombin inhibitors or GP IIb/IIIa inhibitors in thrombolysis has been investigated with encouraging, but limited, success. The usefulness of combining both agents as adjunctive therapy to thrombolysis has not been fully explored. Following platelet-rich thrombus formation in the rabbit, argatroban (3 mg/kg), G4120 (0.5 mg/kg), G4120 plus heparin (200 U/kg), or G4120 plus argatroban were intravenously infused over 60 minutes. Alteplase was given as intravenous boluses (0.45 mg/kg) at 15-minute intervals up to 4 doses or until reperfusion. Blood flow and bleeding time were monitored for 2 hours. The combination of G4120 plus argatroban resulted in a persistent patency in 5 of 7 animals compared with 0 of 6 for argatroban alone (p=0.02), 1 of 6 for G4120 alone (p=0.08), and 2 of 6 for G4120 plus heparin (p=0.2). Although during the infusion the bleeding times were longer in the groups that received G4120 (26+/-7.7 minutes vs. 14+/-10 minutes, p<0.05), by the end of the experiment there were no statistically significant differences. Similarly, during the infusion the activated partial thromboplastin times (aPTT) was higher in groups that received heparin or argatroban (99+/-51 seconds vs. 32+/-7.6 seconds, p<0.001), but by the end of the experiment the aPTTs had returned to close to baseline in all groups except the G4120 plus heparin group. These results suggest that lysis of platelet-rich thrombus with alteplase requires the addition of both potent platelet and thrombin inhibitors. Specifically designed agents, G4120 and argatroban, are effective without additional increased risk for bleeding.

The use of glycoprotein IIb/IIIa inhibitors in patients with coronary artery disease

Platelet membrane glycoprotein IIb/IIIa inhibitors, a new class of potent antiplatelet agents, have been used in the treatment of acute coronary syndromes as well as in the prevention of complications after percutaneous coronary interventions. Approximately 50,000 patients with coronary artery disease have been enrolled in randomized studies of glycoprotein IIb/IIIa inhibitors. The purpose of this article is to review the pharmacology of glycoprotein IIb/IIIa inhibitors, the results of the clinical trials using these agents, and their current use in percutaneous coronary interventions and the treatment of acute coronary syndromes.

Primary versus rescue percutaneous coronary intervention in patients with acute myocardial infarction

OBJECTIVE

To compare angiographic and clinical outcomes of patients with acute myocardial infarction (AMI) who underwent primary percutaneous coronary intervention (PCI) versus rescue PCI following failed thrombolysis.

BACKGROUND

Patients presenting with AMI are treated either with primary PCI or with thrombolysis. When thrombolysis fails, rescue PCI is performed.

METHODS AND RESULTS

We compared the outcome of 105 consecutive patients with AMI who underwent either primary PCI (60 patients) or rescue PCI (45 patients) between January 1997 and January 1999. The patients were followed for up to 6 months. Time delay to reperfusion was significantly longer in the rescue PCI group (354 vs. 189 min; p < 0.001). The majority of patients received a stent (93%). Glycoprotein (GP) IIb/IIIa inhibitors were used in 53% of patients in the primary PCI group and in 22% in the rescue group. TIMI grade 3 flow was achieved in 93.3% of patients in the primary PCI group and in 88.8% in the rescue group (p = 0.08). Post-procedure ejection fraction was 53% in the primary PCI group and 47% in the rescue group (p = 0.014). A composite endpoint of death, recurrent MI, repeat PCI, coronary artery bypass grafting (CABG) and recurrent angina at 6 months occurred in 35% of the patients in the primary PCI group and 26.7% in the rescue group (p = 0.36).

CONCLUSION

Despite a significant delay to reperfusion and a lower immediate post-procedure ejection fraction, the clinical outcome of patients treated with rescue PCI following failed thrombolysis appears to be similar to that of patients treated with primary PCI at 6 months.

Delayed rejection of soluble tumor necrosis factor receptor-secreting tumor allografts

BACKGROUND

Exogenous soluble tumor necrosis factor receptor (TNFR) has been shown to be an effective immunosuppressant. It has yet to be tested whether tissues secreting soluble TNFR, when transplanted into a foreign host, could locally generate immunosuppression and therefore manifest prolonged survival.

METHODS

A murine tumor line was transfected with the gene encoding a chimeric protein consisting of the extracellular domain of the human 75-kDa TNFR fused to the Fc region of the human IgG1 heavy chain. This tumor line was then injected into allogeneic recipients.

RESULTS

Transfected tumor cells were shown to secrete soluble TNFR. When transplanted into minor histocompatibility antigen-disparate allogeneic recipients, these tumor cells grew as a solid tumor and resisted rejection, whereas untransfected tumors and interleukin-4 receptor transfectant controls were rejected within 4 weeks. The resistance to rejection could be reversed by coadministration of an anti-TNFR monoclonal antibody.

CONCLUSIONS

Prolongation of graft survival can be achieved by genetically altering transplanted tissue to secrete soluble cytokine receptors.

Pulmonary cholesterol crystal embolization

BACKGROUND

Cholesterol crystal embolization (CCE) has been documented to affect nearly every organ system. However, CCE involving the lung is distinctly uncommon and has been documented only in the setting of an aortocaval fistula.

DESIGN

A case at the Massachusetts General Hospital and a MEDLINE search of English-language medical articles published between 1966 and 1997 provide the basis for this report.

RESULTS

The precipitants of CCE include invasive vascular procedures, anticoagulant therapy, and thrombolysis. The most common symptoms include claudication of the calf, gastrointestinal bleeding, and weight loss. The most common signs include livedo reticularis, gangrene, and ulcers. Azotemia, proteinuria, normocytic anemia, and eosinophilia often are found. Herein is described the first pathologically confirmed case of CCE to the lung in the absence of an arteriovenous fistula.

CONCLUSION

Pulmonary hemorrhage should now be included in the diverse list of presenting signs of CCE. Moreover, CCE should be considered in the differential diagnosis of pulmonary-renal syndromes.

MHC class I expression and CD8+ T cell development in TAP1/beta 2-microglobulin double mutant mice

We have bred to homozygosity gene disruptions for the transporter associated with antigen processing 1 (TAP1) and beta 2-microglobulin (beta 2m), each of which plays a distinct role in providing class I MHC subunits. Surface expression of H-2Kb or Db on cells derived from TAP1/beta 2m -/- mice was undetectable by immunofluorescence or immunoprecipitation, unlike the situation observed for TAP1 -/- and beta 2m -/- single mutant mice. Yet, TAP1/beta 2m -/- cells were able to elicit a CD8+ cytotoxic T cell (CTL) response in mice of different H-2 haplotypes and could be killed by anti-H-2b specific CTL. Furthermore, TAP1/beta 2m -/- skin grafts were rejected by bm1 mutant mice. This suggests that very low levels of conformed class I heavy chains can reach the cell surface even in the complete absence of TAP1 and beta 2m gene products, and that these molecules may select a functional CD8+ T cell repertoire. Indeed, CD4-CD8+ T cells were detected in TAP1/beta 2m -/- mice, but in numbers lower than in either of the single mutant mice. Nonetheless, it was possible to elicit a CD8+ allospecific and H-2b reactive CTL response in TAP1/beta 2m -/- mice. In line with this, TAP1/beta 2m -/- mice rapidly rejected TAP1/beta 2m +/- skin grafts. Our results suggest that some MHC class I heavy chains in TAP1/beta 2m -/- cells can reach the cell surface in a form that allows recognition by allospecific CTL and positive selection of CD8+ T cells.