Challenges in treating elderly patients with haemophilia: a focus on cardiology.

Seventy years ago, the average life expectancy for patients with severe haemophilia A was less than 17 years. Today, due to the availability of safe and effective clotting factor concentrates, life expectancy is nearly normal, at least in patients without viral infections. More individuals are living into their 70s and 80s, acquiring a range of diseases that are common in elderly persons. One of the most important challenges includes the treatment of comorbidities, especially cardiovascular diseases. Although most evidence suggests that haemophilia, at least the severe manifestation, partially protects against myocardial infarction, stroke and venous thromboembolism, typical cardiovascular risk factors can still be present despite the clotting defect. Patients with haemophilia are equally or even more prone to obesity, hypertension, diabetes, and dyslipidaemia, and this is especially true for HIV-infected individuals using highly active antiretroviral therapy. The management of elderly haemophilia patients with cardiovascular comorbidities is hampered by a lack of evidence-based guidelines. Nevertheless, experience in treating cardiovascular disease is growing amongst the haemophilia community, and several authors have published their own recommendations for managing a variety of commonly encountered cardiovascular scenarios in haemophilia patients. Basic recommendations exist for risk-factor management, the adaptation of factor replacement therapy in the at-risk elderly, management of coronary revascularization, the management of acute coronary syndrome and atrial fibrillation. This review outlines our current knowledge about cardiovascular risk in elderly haemophilia patients, recommendations for clinical decision making, and our own experiences of managing individuals with coronary heart disease and atrial fibrillation.

Platelet reactivity and clopidogrel resistance are associated with the H2 haplotype of the P2Y12-ADP receptor gene.

BACKGROUND: Platelet hyperreactivity was reported in clopidogrel-naiotave carriers of the H2 haplotype of the P2Y(12) platelet ADP receptor. Here, we studied the influence of this genetic variant on clopidogrel responsiveness. METHODS: ADP-mediated (5 micromol/L) platelet aggregation was determined by impedance (Omega) aggregometry in 43 clopidogrel-naïve blood donors and 557 patients treated with aspirin and clopidogrel after percutaneous coronary stent implantation. A cut-off of 5 Omega was used to classify the aggregation response. Haplotype tagging single nucleotide polymorphism G52T was genotyped using a TaqMan assay. RESULTS: The number of H2 alleles correlated with aggregation in clopidogrel-naïve subjects in healthy subjects (p=0.041): impedance results were 8.4+/-3.6, 10.5+/-1.6 and 12.5+/-2.1 Omega in carriers of the H1/H1 (n=30), H1/H2 (n=11) and H2/H2 (n=2) haplotypes, respectively. 87.1% (n=485) and 12.9% (n=72) of clopidogrel treated patients were responders and nonresponders, respectively. Women were more likely to be nonresponders (O.R. 3.90 [95% CI 2.34-6.50]). Carriers of a H2/H2 haplotype (n=14) exhibited stronger aggregation than patients with at least one H1 allele (6.3+/-7.5 vs. 1.8+/-3.3 Omega, p=0.0212) and were more frequently nonresponders (p=0.004). Consequently, the H2/H2 haplotype was associated with clopidogrel resistance (O.R. 5.42 [95% CI 1.82-16.11]). This risk factor was independent of the gender effect. CONCLUSIONS: This is the first large study in clopidogrel treated patients suggesting that a homozygote H2 genotype contributes to clopidogrel resistance. The clinical significance of this finding remains to be demonstrated.

Tirofiban optimizes platelet inhibition for immediate percutaneous coronary intervention in high-risk acute coronary syndromes.

It was the aim of this study to compare the efficacy of early platelet inhibition by 600 mg clopidogrel and acetylsalicylic acid (ASA) to a triple therapy including a glycoprotein IIb-IIIa receptor blocker. Immediate percutaneous coronary intervention (PCI) is recommended for high-risk acute coronary syndromes. In this setting the efficacy of platelet inhibition is unknown. One hundred patients were randomized to receive ASA and 600 mg clopidogrel, or additional open-label tirofiban (bolus of 10 microg/kg body weight followed by continued infusion of 0.15 microg/kg body weight per minute) as soon as non-ST-segment elevation myocardial infarction was diagnosed. The primary endpoint was the reduction of infarct size determined by post-interventional increases of cardiac troponin T (cTnT). Secondary endpoints included platelet function measured by optical and impedance aggregometry using ADP (5 and 20 microM) and collagen (1 microg/ml) as platelet agonists. Tirofiban maximized platelet inhibition (p < 0.0001) immediately and was associated with significantly lower post-interventional cTnT concentrations (p = 0.0352). In the dual platelet inhibition arm, clopidogrel was not effective in 69% of patients at the time of coronary intervention, and still in 47%, if pre-treatment time was >120 minutes. The frequency of cardiovascular (death, myocardial infarction, revascularization) and bleeding events was comparable. Platelet aggregation is not adequately inhibited in cTnT-positive patients in the setting of immediate PCI with very short pre-treatment times. Only tirofiban provided consistent and effective inhibition of platelet aggregation at the time of immediate or very early invasive therapy.

Determination of aspirin responsiveness by use of whole blood platelet aggregometry.

BACKGROUND: Insufficient platelet inhibition is associated with an increased cardiovascular risk in up to 30% of patients taking regular doses of aspirin. We describe an assay to study aspirin responsiveness. METHODS: We performed impedance aggregometry on diluted whole blood with 1 mg/L collagen and 0.5 mmol/L arachidonic acid (AA). We measured thromboxane B(2) (TXB(2)) by RIA. We examined 66 healthy control individuals, 144 aspirin users with stable coronary artery disease (CAD), and 245 CAD patients treated with aspirin and clopidogrel. Nonresponsive samples were incubated with excess DL-lysinmonoacetylsalicylic acid. RESULTS: Assay imprecision (CV) was 9.8% and 8.2% at mean (SD) 6-min impedance of 13.7 (2.8) Omega and 13.6 (2.3) Omega for collagen and AA, respectively. Collagen induced stronger aggregation (P = 0.0199) in women [n = 28, 14.6 (2.4) Omega] than in men [n = 38, 13.1 (2.9) Omega], even after sample incubation with 0.1 mmol/L acetylsalicylic acid (ASA) or 1 micromol/L terbogrel, a combined inhibitor of thromboxane synthase and receptors. The sex association persisted in aspirin users, but not if clopidogrel was also taken. A 6-min impedance >8 Omega with collagen (mean - 2 SD of the controls) was taken as evidence of nonresponsiveness, particularly if incubation with ASA did not inhibit aggregation further (>2 Omega). Compared with AA, collagen identified more nonresponsive samples among aspirin users (15%) and CAD patients who also received clopidogrel (10%). Incubation with ASA improved inhibition of aggregation in 70% of samples and consistently reduced TXB(2) formation during aggregation. CONCLUSIONS: Impedance aggregometry may prove useful to study aspirin responsiveness, and incubation with ASA may help to identify nonresponders and classify resistance.

Determination of clopidogrel resistance by whole blood platelet aggregometry and inhibitors of the P2Y12 receptor.

BACKGROUND: Inhibition of platelet aggregation by clopidogrel may be insufficient in up to 30% of users. These nonresponders carry an increased risk of cardiovascular events. We reported here a simple assay to study clopidogrel responsiveness. METHODS: Electrical impedance aggregometry was performed in diluted whole blood in the presence of 5 and 20 micromol/L ADP. Some samples were incubated with 0.1 mmol/L methyl-S-adenosine monophosphate (MeSAMP), a P2Y12 receptor blocker, to maximize inhibition of aggregation before aggregometry. To validate the assay, we analyzed 6-min impedance in 21 healthy probands and 244 patients with coronary artery disease (CAD). RESULTS: At 5 micromol/L ADP, the imprecision of the assay was 11%. Mean (SD) impedance of the healthy cohort was 12.2 (2.2) Omega. The mean - 3 SD was used to define the cutoff for clopidogrel responsiveness: responders and nonresponders exhibited a 6-min impedance < or =5 Omega and >5 Omega, respectively. Samples from nonresponders were incubated with MeSAMP and analyzed again to distinguish pharmacokinetic and pharmacodynamic types of resistance. Sixteen percent of CAD patients were classified as nonresponders (38 and 2 cases of pharmacokinetic and pharmacodynamic resistance, respectively). Female sex was strongly associated with clopidogrel resistance (P = 0.0002, Fisher exact test). A higher clopidogrel loading dose (P = 0.0353, Mann-Whitney U-test) was given to responders (median, 450 mg) than nonresponders (median, 300 mg). Age and cardiovascular diagnosis showed no significant associations. CONCLUSIONS: Impedance aggregometry using 5 mumol/L ADP is a useful tool for studying clopidogrel responsiveness. MeSAMP allows characterization of responsiveness "on treatment" and may be useful for optimizing clopidogrel dosing.

Role of erythropoietin in anemia after heart transplantation.

BACKGROUND: Anemia after heart transplantation is common; however, there are scant data on etiology and treatment. This study evaluates type of anemia and the effects of erythropoietin therapy. METHODS: In 37 anemic heart transplant recipients (31 male/59.1+/-10.3 years/hemoglobin <12.0 g/dl), complete anemia work-up was performed including erythropoietin determination. For three months, 12 anemic patients with renal failure (9 male/64.1+/-13.6 years) were treated with 1-3x4000 IU of epoietin beta/week; treatment endpoints were hemoglobin levels and quality of life as determined by questionnaire. RESULTS: In 31 patients no other cause of anemia than renal insufficiency (mean creatinine 1.9+/-0.9 mg/dl, mean calculated GFR 50.8+/-21.5 ml/min, no hemodialysis) was found; in 93.5% of these patients with renal insufficiency, measured erythropoietin levels were markedly lower than predicted [Beguin Y, Clemons GK, Pootrakul P, Fillet G. Quantitative assessment of erythropoiesis and functional classification of anemia based on measurements of serum transferrin receptor and erythropoietin. Blood 1993; 81(4):1067-1076.]. There was an inverse correlation of hemoglobin levels with serum creatinine/creatinine clearance and a strong trend for inverse correlation of erythropoietin levels. All 12 patients treated with erythropoietin showed a significant increase in hemoglobin levels after three months returning to pre-treatment values within 3 months of cessation of therapy (before study 10.8+/-1.1 g/dl, end of study 14.1+/-1.7 g/dl, three months after end of study 11.6+/-2.1 g/dl; p<0.005). Quality of life was significantly improved in eight patients (75%). CONCLUSIONS: Anemia after heart transplantation is associated with moderate renal failure and low erythropoietin levels in most patients. Erythropoietin therapy resulted in increased hemoglobin levels in all and improved quality of life in 75% of patients. Erythropoietin may be a superior marker of functional renal impairment after heart transplantation; its therapeutic substitution allows effective anemia management and improves quality of life.