Improvement of the cardiac marker N-terminal-pro brain natriuretic peptide through adjustment for renal function: a stratified multicenter trial.

BACKGROUND: N-terminal-pro brain natriuretic peptide (NT-proBNP) is a useful cardiac marker that is also influenced by renal dysfunction. It was our objective to assess the relationship between NT-proBNP concentrations in plasma and worsening renal function, and to attempt adjustment of NT-proBNP for renal dysfunction in a prospective, stratified multi-center study. METHODS: We stratified 203 male patients according to their cardiac status and the estimated glomerular filtration rate (eGFR). Cardiac disease was assessed by medical history, physical examination and standardized echocardiography. Patients were stratified according to the following: absence of cardiac history and abnormalities (control, CTRL, n=66), cardiac history without left ventricular hypertrophy (LVH) or left ventricular systolic dysfunction (LVD) (history, n=30), LVH without systolic dysfunction (LVH, n=68), and LVD [ejection fraction (EF) <40%, LVD, n=39]. Renal disease was stratified according to the eGFR: 15-30 mL/min (n=52), 31-75 mL/min (n=99), and >75 mL/min (n=52). RESULTS: NT-proBNP was correlated with eGFR in the entire study population and for all levels of cardiac disease (all p<0.01). Regression analysis allowed adjustment of NT-proBNP for eGFR in a continuous manner, and this adjustment significantly improved the predictive value (receiver operating characteristic curve for symptomatic LVD from 0.80 to 0.86, p<0.01; sensitivity from 74% to 83% and specificity from 68% to 79%). CONCLUSIONS: NT-proBNP correlates inversely and significantly with eGFR throughout all levels of cardiac strata. We propose for the first time a continuous adjustment algorithm which markedly improves the predictive values of NT-proBNP in male patients with impaired renal function.

Association of angiotensin-converting enzyme 2 (ACE2) gene polymorphisms with parameters of left ventricular hypertrophy in men. Results of the MONICA Augsburg echocardiographic substudy.

Angiotensin-converting enzyme (ACE) activity is considered to be of major importance for the conversion of angiotensin (Ang) I to Ang II. Recently, a second ACE, named ACE2, has been identified. Experimental data provide evidence that ACE2 might be involved in modulating cardiac structure and function. In the present explorative study, we assessed whether polymorphisms in the ACE2 gene are related to echocardiographically determined parameters of left ventricular mass, structure or function in the general population. Five intronic single nucleotide polymorphisms (SNPs) were genotyped using the 5'-exonuclease activity (TaqMan) assay in the echocardiographic substudy of the third MONICA Augsburg survey. As ACE2 is located on the X chromosome, women and men were analysed separately. Four SNPs showed high pairwise linkage disequilibrium (rs4646156, rs879922, rs4240157 and rs233575). The minor alleles of these four SNPs were associated with higher left ventricular mass index (LVMI) and higher septal wall thickness (SWT) in men. Likewise, male carriers of a common haplotype (frequency 29.9%) consisting of the minor alleles of these four SNPs displayed higher values for LVMI and SWT than non-carriers (LVMI: TGGC 98.8+/-1.52 vs non-TGGC 94.8+/-0.99 g/m(2), p=0.027; SWT: TGGC 11.5+/-0.14 vs non-TGGC 11.1+/-0.09 mm, p=0.019). Furthermore, this haplotype was associated with an increased odds ratio (OR) for left ventricular hypertrophy (OR 3.10, p=0.006). In women, similar but less pronounced and consistent trends were observed. No association was observed between any of these SNPs and parameters of left ventricular systolic or diastolic function nor with blood pressure levels. This study provides evidence that genetic variants in the ACE2 gene may be associated with left ventricular mass, SWT and left ventricular hypertrophy in hemizygous men.

Association of the metabolic syndrome with early coronary disease in families with frequent myocardial infarction.

This study examined the extent to which the metabolic syndrome (MS) augments the risk for major cardiovascular events in healthy patients with a strong genetic background for coronary artery disease (CAD). In a prospective cohort study, we examined 1,316 patients without previously diagnosed CAD or diabetes mellitus. Patients were participants of the Regensburg Myocardial Infarction Family Study, in which > or = 2 family members had severe CAD and 1 had myocardial infarction (MI) at < 60 years of age. During a 2-year follow-up, the incidence of first cardiovascular events (MI, revascularization, and cardiac death) was compared between those with and without the MS at baseline. In all previously unaffected family members, the presence of MS increased the hazard ratio for first manifestation of CAD by a factor of 1.9 (p = 0.030), which resulted in an event rate of 7.1% during follow-up. Specifically in young patients (< or = 50 years old, n = 422), we identified the MS as a major event predictor that conferred a 5.8-fold increased relative risk for first cardiovascular events compared with patients without the MS (95% confidence interval 1.4 to 23.8, p = 0.015, event rate 6.2%). Remarkably, of the individual MS components, obesity was strongly associated with incident MI (relative risk 4.4, 95% confidence interval 1.5 to 13.0, p = 0.007). Thus, the MS strongly predicts cardiac morbidity and mortality in healthy patients with a family background of CAD.

Enhanced ventilatory response to exercise in patients with chronic heart failure and central sleep apnea.

BACKGROUND: In patients with chronic heart failure (CHF), central sleep apnea (CSA) and enhanced ventilatory response (VE/VCO2 slope) to exercise are common. Both breathing disorders alone indicate poor prognosis in CHF. Although augmented chemosensitivity to CO2 is thought to be one important underlying mechanism for both breathing disorders, it is unclear whether both breathing disorders are related closely in patients with CHF. METHODS AND RESULTS: We investigated 20 CHF patients with clinically important CSA (apnea-hypopnea-index (AHI), number of episodes per hour >or=15) and 10 CHF patients without CSA. Patients with and without CSA did not differ with respect to exercise capacity (peak VO2, 63.4+/-3.4% versus 60.8+/-4.4% of predicted value; P=0.746) and left ventricular ejection fraction (LVEF, 31+/-2% versus 31+/-3%; P=0.948). The AHI was not correlated with exercise capacity (peak VO2, percent of predicted value; P=0.260) and LVEF (percent, P=0.886). In contrast, the positive correlation of the VE/VCO2 slope, determined by cardiopulmonary exercise testing, with the AHI was highly significant (P<0.001). The VE/VCO2 slope was significantly increased in patients with CSA compared with those without CSA (29.7 versus 24.9; P<0.001). CONCLUSIONS: The ventilatory response to exercise is significantly augmented in CHF patients with CSA compared with those without. In contrast to peak VO2 and LVEF, the VE/VCO2 slope is strongly related to the severity of CSA in patients with CHF, which underscores an augmented chemosensitivity to CO2 as a common underlying pathophysiological mechanism.

Association of polymorphisms of the apolipoprotein(a) gene with lipoprotein(a) levels and myocardial infarction.

BACKGROUND: Serum lipoprotein(a) [Lp(a)] concentration is largely determined by variability at the apolipoprotein(a) gene locus. Most prominent effects relate to polymorphisms in the promoter (a pentanucleotide [PN] repeat) and coding regions (a kringle IV [K4] repeat), the latter of which also affects Lp(a) particle size. The impact of these polymorphisms on cardiovascular risk is poorly understood. METHODS AND RESULTS: We studied both polymorphisms and Lp(a) levels in 834 registry-based myocardial infarction (MI) patients (38% women) and 1548 population-based controls. Lp(a) concentrations were inversely related with the numbers of K4 and PN repeats. However, the effect of the PN polymorphism was restricted to subjects producing small Lp(a) particles (8 PN 8.7 mg/dL; P<0.0001). The odds to present with MI were elevated in individuals producing small Lp(a) particles (

Functional improvement in heart failure patients treated with beta-blockers is associated with a decline of cytokine levels.

BACKGROUND: In patients with severe heart failure (CHF), chronically elevated cytokine levels document a systemic inflammation. Experimental data suggest that activation of the beta-adrenergic system may participate in this inflammatory response. Herein, we studied as to whether beta-adrenergic blockade on top of standard CHF therapy affects plasma cytokine levels (interleukin-6 [IL-6] and tumor necrosis factor alpha [TNFalpha]). Moreover, we studied if beta-blocker related changes of these cytokines correspond to changes in left ventricular (LV) function and exercise capacity. METHODS: In a prospective study, 21 patients with stable CHF (NYHA functional class II-III, ejection fraction <40%, mean age 57.6+/-12.4 years) were treated with captopril (100-150 mg/day), furosemide (40-120 mg/day), and/or digoxin (0.1-0.2 mg/day) for at least 1 month before they entered a 4 week run-in period in which dosages were kept unchanged. Metoprololsuccinate was administered in increasing dosages (up to 190 mg/day) for the following 3 months. Clinical, echocardiographic, spiroergometric, and biochemical changes were assessed at the start and the end of the run-in period as well as after 3 month of beta-blockade. RESULTS: As compared to 210 healthy volunteers, CHF patients, prior to beta-blockade, presented with markedly elevated IL-6 (8.9+/-9.9 vs. 2.1+/-0.5 pg/ml; p<0.05) and TNFalpha levels (1.51+/-0.49 vs. 0.64+/-0.15 pg/ml; p<0.05) levels. In CHF patients, 3 month of beta-blockade lowered heart rate (84+/-14 vs. 68+/-12 bpm; p<0.01), systolic (131+/-7 vs. 118+/-6 mm Hg; p<0.01), and diastolic blood pressure (78+/-5 vs. 71+/-6 mm Hg; p<0.01). Spiroergometric determined VO2 max (17.8+/-4.5 vs. 19.8+/-4.3 ml/min kg; p=0.013) increased significantly during 3 month of beta-blockade. Moreover, LV functional parameters tended to improve but the interindividual response varied and changes were non-significant. Interestingly, IL-6 levels decreased markedly during beta-blockade (8.9+/-9.9 vs. 4.5+/-3.1 pg/ml; p=0.036), whereas TNFalpha levels remained unchanged. Moreover, significant positive correlations were found between decrease of IL-6 levels and left ventricular end diastolic diameters (r2=0.59; p=0.012), whereas an inverse correlation was found between the decrease of IL-6 and the increase of VO2 max (r2=0.54; p=0.037), respectively. CONCLUSION: In heart failure patients, beta-blockade may lower IL-6 but not TNFalpha levels. Changes of IL-6 during beta-blockade may be related to changes of LV function and geometry.

Angiotensin converting enzyme gene polymorphism and myocardial infarction a large association and linkage study.

The DD genotype of the angiotensin converting enzyme (ACE) polymorphism has been associated with myocardial infarction (MI). However, sample sizes of many case-control studies showing positive association were small and data were inconsistent. Furthermore, no family-based study is available. In a case-control study frequencies of the ACE genotypes were compared in 1319 unrelated patients with previous MI before 60 years of age (616 from the MONICA Augsburg region and 703 from rehabilitation centers in south Germany) and in 2381 population controls from the MONICA Augsburg study region). Furthermore, linkage and association of the ACE I/D polymorphism with MI were tested in 246 informative families using the sib-transmission/disequilibrium test (S-TDT).Overall, no excess of the D allele was found in MI patients (frequency 0.53 versus 0.57 in the general population; P=0.2). The ACE DD genotype was even slightly less frequent in groups with MI compared to the general population controls (0.26 versus 0.33 in women and 0.28 versus 0.33 in men). Similar results were also obtained in 247 men with low cardiovascular risk. In the family-based study, the frequency of the D allele was not different in siblings with or without previous MI (0.53 versus 0.50, respectively; S-TDT P=0.15) indicating no linkage or association of the D allele with MI. In a case-control study of MI patients and controls from the general population as well as a family study neither association nor linkage of the ACE D allele with MI was detected despite sample sizes that were among the largest samples studied so far.

Molecular cloning and functional characterization of the upstream rat atrial natriuretic peptide promoter.

OBJECTIVE: The upregulation of left ventricular atrial natriuretic peptide (ANP) serves as a molecular marker of cardiac hypertrophy. The precise mechanisms underlying this gene induction are unclear, since the presently cloned 3.6 kilo base (kb) rat ANP promoter failed to substantially induce coupled reporter genes in chronically hypertrophied hearts. The aim of this study was to clone and to functionally analyse the upstream ANP promoter. DESIGN: Upstream of the known ANP promoter, a 1.5 kb segment was cloned by the promoter walker method and found to harbour a putative CCAAT-binding site as well as multiple putative transcription factor binding sites. This newly cloned segment was ligated with a reporter gene, in vivo transfected into rat myocardium, and analysed under basal conditions or after stimulation with both acute (isovolumetric contractions in the Langendorff apparatus) and chronic wall stress (aortic banding). RESULTS: Reporter gene constructs carrying the newly cloned segment conferred only little promoter activity. In hearts exposed to acute wall stress, the previously cloned 3.6 kb ANP promoter as well as a constitutive promoter (pGL3 promoter vector) were active but markedly suppressed after extension with the newly cloned upstream promoter (-88.1 and -85.5%; P < 0.05 respectively). Site directed mutagenesis of two AP-2 transcription factor binding sites (base pairs -3946 to -3954 or -4192 to -4200) eliminated this silencing effect. In hearts with chronic pressure overload hypertrophy as well as in normal, unstimulated hearts the activity of the 3.6 kb ANP promoter was weak and also abolished after ligation with the 1.5 kb upstream segment. Moreover, both putative AP-2 binding sites within the upstream rat ANP promoter bound specifically to nuclear proteins of unstimulated, acute and chronic pressure overloaded hearts as demonstrated by electrophoresis mobility shift assays. CONCLUSION: Novel silencer elements were cloned, localized to two AP-2 binding sites in the upstream ANP promoter, and functionally characterized. Given that the putative upregulation of left ventricular ANP by the extensively studied 3.6 kb proximal promoter region is substantially diminished by the newly cloned segment, the functional significance of regulatory elements within the proximal promoter region should be re-evaluated. The molecular mechanism causing ANP mRNA induction in left ventricular hypertrophy remains obscure.

No association of interleukin-6 gene polymorphism (-174 G/C) with myocardial infarction or traditional cardiovascular risk factors.

BACKGROUND: Recently, a polymorphism at position -174 (G>C) of the interleukin-6 (IL-6) promoter was found to be associated with an increased prevalence of myocardial infarction (MI). The aim of the present study was to further investigate the association of the IL-6 -174 G/C allele status with specific end organ damage, i.e. myocardial infarction in large population-based samples. METHODS: Individuals from two Bavarian samples of MI patients (total n=1322) and the population-based Augsburg MONICA survey (1023 unselected controls) were studied by questionnaire, physical examination, echocardiographical assessment and biochemical analyses. The -174 G/C polymorphism was genotyped using a newly established PCR-RFLP. IL-6 levels were measured in a subset of 574 MI patients. RESULTS: In the population-based sample, the IL-6 genotype was neither associated with traditional cardiovascular risk factors (systolic and diastolic blood pressure, total cholesterol, HDL and LDL cholesterol, body mass index, diabetes mellitus) nor with cardiac structural or functional parameters (left ventricular mass index, ejection fraction, diastolic inflow pattern). Moreover, the genotype distribution of the -174 G/C polymorphism was not different in MI patients (GG: 34.1%; GC: 47.4%; CC: 18.5%) and population-based controls (GG: 32.4%; GC: 48.8%; CC: 18.9%) (p=0.67). IL-6 levels were neither related to the -174 G/C polymorphism (p=0.29) nor to ACE-inhibitor treatment (2.16 with vs. 2.09 pg/ml without ACE-inhibitor, p=0.27). However, patients receiving statins displayed significantly lower IL-6 levels (1.83 vs. 2.32 pg/ml in the group without statins, p<0.0001). CONCLUSIONS: This extensive investigation failed to obtain evidence that the IL-6 -174 G/C promoter polymorphism affects traditional cardiovascular risk factors or the prevalence of myocardial infarction in a Caucasian sample.

C-reactive protein as predictor of death in end-stage diabetic nephropathy: role of peripheral arterial disease.

BACKGROUND: Patients with diabetes type 2 receiving dialysis therapy have a poor survival prognosis, mainly due to cardiovascular events. Increased C-reactive protein (CRP) levels, important in atherosclerosis, are associated with an increased risk for cardiovascular events. However, to date no study has shown the predictive value of CRP in relation to peripheral arterial disease stage. METHODS: We enrolled all 445 prevalent patients with diabetic nephropathy receiving maintenance hemodialysis in 30 centers in Southern Germany from August 1999 to January 2000 for prospective study until December 2003. At inclusion, CRP and a complete clinical phenotype, including peripheral arterial disease Fontaine Stage were determined. The primary end point was all-cause mortality. RESULTS: A total of 305 (68.5%) patients died. An increased log CRP at study inclusion was significantly associated with an increase in hazard ratio (HR) by multivariate Cox regression for all-cause (HR = 1.5, P= 0.002) and cardiac death (HR = 1.76, P= 0.02) in the entire collective. This result was applicable only to patients with peripheral arterial disease Fontaine stage IV (N= 190, multivariate HR = 1.75 for all-cause mortality, P= 0.006). Possibly due to inadequate power, we observed only an insignificant trend for CRP as predictor of all-cause death in patients without peripheral arterial disease or with less severe forms of peripheral arterial disease (HR = 1.36, P= 0.08). CONCLUSION: In contrast to patients with peripheral arterial disease stage IV, patients with less severe atherosclerosis and elevated CRP are, if any, at less risk for cardiovascular mortality, possibly due to the difference in extent of affected vasculature and thus activated platelets and coagulation. Before judging the predictive value of CRP for mortality, peripheral vessel status should be determined.