Cardiac dysfunction and noncardiac dysfunction as precursors of heart failure with reduced and preserved ejection fraction in the community

BACKGROUND

Heart failure (HF) is a clinical syndrome characterized by signs and symptoms involving multiple organ systems. Longitudinal data demonstrating that asymptomatic cardiac dysfunction precedes overt HF are scarce, and the contribution of noncardiac dysfunction to HF progression is unclear. We hypothesized that subclinical cardiac and noncardiac organ dysfunction would accelerate the manifestation of HF.

METHODS AND RESULTS

We studied 1038 participants of the Framingham Heart Study original cohort (mean age, 76±5 years; 39% men) with routine assessment of left ventricular systolic and diastolic function. Major noncardiac organ systems were assessed with the use of serum creatinine (renal), serum albumin (hepatic), ratio of forced expiratory volume in 1 second to forced vital capacity (FEV(1):FVC ratio; pulmonary), hemoglobin concentration (hematologic/oxygen-carrying capacity), and white blood cell count (systemic inflammation). On follow-up (mean, 11 years), there were 248 incident HF events (146 in women). After adjustment for established HF risk factors, antecedent left ventricular systolic dysfunction (hazard ratio, 2.33; 95% confidence interval, 1.43 to 3.78) and diastolic dysfunction (hazard ratio, 1.32; 95% confidence interval, 1.01 to 1.71) were associated with increased HF risk. After adjustment for cardiac dysfunction, higher serum creatinine, lower FEV1:FVC ratios, and lower hemoglobin concentrations were associated with increased HF risk (all P<0.05); serum albumin and white blood cell count were not. Subclinical dysfunction in each noncardiac organ system was associated with a 30% increased risk of HF (P=0.013).

CONCLUSIONS

Antecedent cardiac dysfunction and noncardiac organ dysfunction are associated with increased incidence of HF, supporting the notion that HF is a progressive syndrome and underscoring the importance of noncardiac factors in its occurrence.

Anodal stimulation: an underrecognized cause of nonresponders to cardiac resynchronization therapy

OBJECTIVE

The purpose of this study was to determine if anodal stimulation accounts for failure to benefit from cardiac resynchronization therapy (CRT) in some patients.

BACKGROUND

Approximately 30-40% of patients with moderate to severe heart failure do not have symptomatic nor echocardiographic improvement in cardiac function following CRT. Modern CRT devices allow the option of programming left ventricular (LV) lead pacing as LV tip to right ventricular (RV) lead coil to potentially improve pacing thresholds. However, anodal stimulation can result in unintentional RV pacing (anode) instead of LV pacing (cathode).

METHODS

Patients enrolled in our center's CRT registry had an echocardiogram, 6-minute walk (6MW), and Minnesota Living with HF Questionnaire (MLHFQ) pre-implant and 6 months after CRT. Electrocardiograms (12 lead) during RV, LV, and biventricular (BiV) pacing were obtained at the end of the implant in 102 patients. Anodal stimulation was defined as LV pacing QRS morphology on EKG being identical to RV pacing or consistent with fusion with RV and LV electrode capture. LV end systolic volume (LVESV) was measured by echo biplane Simpson's method and CRT responder was defined as 15% or greater reduction in LVESV.

RESULTS

Of the 102 patients, 46 (45.1%) had the final LV lead pacing configuration programmed LV (tip or ring) to RV (coil or ring). 3 of the 46 subjects (6.5%) had EKG findings consistent with anodal stimulation, not corrected intraoperatively. All anodal stimulation patients were nonresponders to CRT by echo criteria (reduction in LVESV 13.3 ± 0.6%, increase in EF 5.0 ± 1.4%) compared to 46% responders for those without anodal stimulation, (change in LVESV 18.7 ± 25.6%, EF 7.6 ±10.9%). None of the anodal stimulation patients were responders for the 6 minute walk, compared to 32 of 66 (48%) of those without anodal stimulation.

CONCLUSION

Anodal stimulation is a potential underrecognized and ameliorable cause of poor response to CRT.

Diastolic relaxation and compliance reserve during dynamic exercise in heart failure with preserved ejection fraction

BACKGROUND

Recent studies have examined haemodynamic changes with stressors such as isometric handgrip and rapid atrial pacing in heart failure with preserved ejection fraction (HFpEF), but little is known regarding left ventricular (LV) pressure-volume responses during dynamic exercise.

OBJECTIVE

To assess LV haemodynamic responses to dynamic exercise in patients with HFpEF.

METHODS

Twenty subjects with normal ejection fraction (EF) and exertional dyspnoea underwent invasive haemodynamic assessment during dynamic exercise to evaluate suspected HFpEF.

RESULTS

LV end-diastolic pressure was elevated at rest (>15 mm Hg, n=18) and with exercise (≥20 mm Hg, n=20) in all subjects, consistent with HFpEF. Heart rate (HR), blood pressure, arterial elastance and cardiac output increased with exercise (all p<0.001). Minimal and mean LV diastolic pressures increased by 43-56% with exercise (both p<0.0001), despite a trend towards a reduction in LV end-diastolic volume (p=0.08). Diastolic filling time was abbreviated with increases in HR and the proportion of diastole that elapsed prior to estimated complete relaxation increased (p<0.0001), suggesting inadequate relaxation reserve relative to the shortening of diastole. LV diastolic chamber elastance acutely increased 50% during exercise (p=0.0003). Exercise increases in LV filling pressures correlated with changes in diastolic relaxation rates, chamber stiffness and arterial afterload but were not related to alterations in preload volume, HR or cardiac output.

CONCLUSION

In patients with newly diagnosed HFpEF, LV filling pressures increase during dynamic exercise in association with inadequate enhancement of relaxation and acute increases in LV chamber stiffness. Therapies that enhance diastolic reserve function may improve symptoms of exertional intolerance in patients with hypertensive heart disease and early HFpEF.

Diuretic strategies in patients with acute decompensated heart failure

BACKGROUND

Loop diuretics are an essential component of therapy for patients with acute decompensated heart failure, but there are few prospective data to guide their use.

METHODS

In a prospective, double-blind, randomized trial, we assigned 308 patients with acute decompensated heart failure to receive furosemide administered intravenously by means of either a bolus every 12 hours or continuous infusion and at either a low dose (equivalent to the patient's previous oral dose) or a high dose (2.5 times the previous oral dose). The protocol allowed specified dose adjustments after 48 hours. The coprimary end points were patients' global assessment of symptoms, quantified as the area under the curve (AUC) of the score on a visual-analogue scale over the course of 72 hours, and the change in the serum creatinine level from baseline to 72 hours.

RESULTS

In the comparison of bolus with continuous infusion, there was no significant difference in patients' global assessment of symptoms (mean AUC, 4236±1440 and 4373±1404, respectively; P=0.47) or in the mean change in the creatinine level (0.05±0.3 mg per deciliter [4.4±26.5 μmol per liter] and 0.07±0.3 mg per deciliter [6.2±26.5 μmol per liter], respectively; P=0.45). In the comparison of the high-dose strategy with the low-dose strategy, there was a nonsignificant trend toward greater improvement in patients' global assessment of symptoms in the high-dose group (mean AUC, 4430±1401 vs. 4171±1436; P=0.06). There was no significant difference between these groups in the mean change in the creatinine level (0.08±0.3 mg per deciliter [7.1±26.5 μmol per liter] with the high-dose strategy and 0.04±0.3 mg per deciliter [3.5±26.5 μmol per liter] with the low-dose strategy, P=0.21). The high-dose strategy was associated with greater diuresis and more favorable outcomes in some secondary measures but also with transient worsening of renal function.

CONCLUSIONS

Among patients with acute decompensated heart failure, there were no significant differences in patients' global assessment of symptoms or in the change in renal function when diuretic therapy was administered by bolus as compared with continuous infusion or at a high dose as compared with a low dose. (Funded by the National Heart, Lung, and Blood Institute; ClinicalTrials.gov number, NCT00577135.).

The effect of the brain-type natriuretic peptide single-nucleotide polymorphism rs198389 on test characteristics of common assays

OBJECTIVE

To assess in a US general adult population the effect of the functional single-nucleotide polymorphism rs198389 in the promoter region of the gene of brain-type natriuretic peptide (BNP) on 3 commonly used BNP assays, clinical phenotype, disease prevalence, overall survival, and diagnostic test characteristics of BNP as a biomarker.

PATIENTS AND METHODS

We genotyped for rs198389 in a random sample of the general population (aged ≥ 45 years; n = 1970; enrolled between June 1, 1997, and September 30, 2000) from Olmsted County, Minnesota. Patients were characterized biochemically, clinically, echocardiographically, and regarding BNP molecular forms (2 assays for BNP and 1 assay for amino-terminal proBNP). Median follow-up was 9 years.

RESULTS

Genotype frequencies were in Hardy-Weinberg equilibrium (P = .98): TT genotype, n = 645 (32.7%); TC genotype, n = 983 (49.9%); and CC genotype, n = 342 (17.4%). The C allele independently predicted higher BNP forms (P<.001 for all assays). Genotypes did not differ with regard to clinical and echocardiographic phenotype or overall survival. When previously reported genotype-unadjusted cut points for the detection of left ventricular ejection fraction less than or equal to 40% (n = 37 [1.9%]) and less than or equal to 50% (n = 116 [6.0%]) were used, sensitivity generally increased with the number of C alleles, whereas specificity decreased, both on average by more than 10% for the TT vs CC genotype.

CONCLUSION

The C allele of rs198389 is common in the general US population and is associated with higher concentrations of BNP molecular forms but not with cardiovascular phenotype or survival. The C allele confounds the test characteristics of commonly used assays.

Symptom improvement after upgrade from right ventricular apical to biventricular pacing: Role of right and left ventricular volumes assessed with single-photon emission computed tomographic equilibrium radionuclide angiocardiography

BACKGROUND

In patients with heart failure and reduced left ventricular ejection fraction (LVEF), the effect of upgrading from right ventricular (RV) apical to biventricular pacing on RV and left ventricular (LV) volumes and ejection fraction (EF) is unknown. Also, the relationship of symptom improvement after biventricular upgrade to RV and LV volumes and EF has not been clarified.

METHODS AND RESULTS

Nineteen patients with long-standing persistent RV apical pacing who had heart failure symptoms and echocardiographic LVEF of 0.40 or less underwent upgrade to biventricular pacing. Patients had single-photon emission computed tomographic equilibrium radionuclide angiocardiography immediately before and at 3-6 months after the upgrade procedure, to measure RV and LV volumes and EF. Biventricular upgrade was associated with increase in LVEF and decrease in LV end-diastolic and end-systolic volumes; right ventricular ejection fraction (RVEF) and end-diastolic and end-systolic volumes were unaltered. Patients with improvement in New York Heart Association heart failure class of I or more had larger initial LV end-diastolic volumes than patients without an improvement and had decreased LV end-diastolic and end-systolic volumes comparatively. Symptom improvement was not associated with RVEF and volume change.

CONCLUSION

Symptom improvement with LV remodeling, but not RV remodeling, occurs 3-6 months after biventricular upgrade in patients with heart failure.

Familial aggregation of left ventricular geometry and association with parental heart failure: the Framingham Heart Study

BACKGROUND

Data regarding the familial aggregation of left ventricular (LV) geometry and its relations to parental heart failure (HF) are limited.

METHODS AND RESULTS

We evaluated concordance of LV geometry within 1093 nuclear families in 5758 participants of the original (parents) (n=2351) and offspring (n=3407) cohorts of the Framingham Heart Study undergoing routine echocardiography in mid- to late adulthood. LV geometry was categorized based on cohort- and sex-specific 80th percentile cutoffs of LV mass and relative wall thickness (RWT) into normal (both <80th percentile), concentric remodeling (LV mass <80th percentile; RWT >80th percentile), concentric hypertrophy (both >80th percentile), and eccentric hypertrophy (LV mass >80th percentile; RWT <80th percentile). Within nuclear families, LV geometry was concordant among related pairs (parent-child, sibling-sibling) (P=0.0015) but not among unrelated spousal pairs (P=0.60), a finding that remained unchanged after adjusting for clinical covariates known to influence LV remodeling (age, systolic blood pressure, body mass index), excluding individuals with prevalent HF and myocardial infarction, and varying the thresholds for defining LV geometry. The prevalence of abnormal LV geometry was higher in family members of affected individuals, with recurrence risks of 1.4 for concentric remodeling (95% CI, 1.2 to 1.7) and eccentric hypertrophy (95% CI, 1.1 to 1.8) and 3.9 (95% CI, 3.2 to 4.6) for concentric hypertrophy. In a subset of 1497 offspring, we observed an association between parental HF (n=458) and eccentric hypertrophy in offspring (P<0.0001).

CONCLUSIONS

Our investigation of a 2-generational community-based sample demonstrates familial aggregation of LV geometry, with the greatest recurrence risk for concentric LV geometry, and establishes an association between eccentric LV geometry and parental HF.

Aortic root remodeling over the adult life course: longitudinal data from the Framingham Heart Study

BACKGROUND

Aortic root remodeling in adulthood is known to be associated with cardiovascular outcomes. However, there is a lack of longitudinal data defining the clinical correlates of aortic root remodeling over the adult life course.

METHODS AND RESULTS

We used serial routine echocardiograms in participants of the Framingham Heart Study to track aortic root diameter over 16 years in mid to late adulthood and to determine its short-term (4 years; n=6099 observations in 3506 individuals) and long-term (16 years; n=14,628 observations in 4542 individuals) clinical correlates by multilevel modeling. Age, sex, body size, and blood pressure were principal correlates of aortic remodeling in both short- and long-term analyses (all P < or = 0.01). Aortic root diameter increased with age in both men and women but was larger in men at any given age. Each 10-year increase in age was associated with a larger aortic root (by 0.89 mm in men and 0.68 mm in women) after adjustment for body size and blood pressure. A 5-kg/m(2) increase in body mass index was associated with a larger aortic root (by 0.78 mm in men and 0.51 mm in women) after adjustment for age and blood pressure. Each 10-mm Hg increase in pulse pressure was related to a smaller aortic root (by 0.19 mm in men and 0.08 mm in women) after adjustment for age and body size.

CONCLUSIONS

These longitudinal community-based data show that aortic root remodeling occurs over mid to late adulthood and is principally associated with age, sex, body size, and blood pressure. The underlying basis for these differences and implications for the development of cardiovascular events deserve further study.

Natriuretic peptide pharmacogenetics: membrane metallo-endopeptidase (MME): common gene sequence variation, functional characterization and degradation

Membrane metallo-endopeptidase (MME), also known as neutral endopeptidase 24.11 (EC 3.4.24.11), is involved in the metabolism of natriuretic peptides that play a key role in modulating cardiac structure and function. Common genetic variation in MME has not been addressed by resequencing the gene using DNA from different ethnic populations. We set out to identify and functionally characterize common genetic variation in MME in three ethnic groups. DNA samples from 96 European-American, 96 African-American, and 96 Han Chinese-American healthy subjects were used to resequence MME. Ninety polymorphisms, 65 novel, were identified, including 8 nonsynonymous single nucleotide polymorphisms (nsSNPs). Expression constructs for the nsSNPs were created and COS-1 cells were transfected with constructs for wild type (WT) and variant allozymes. Recombinant proteins were analyzed by quantitative Western blot analysis and by a one-step fluorometric assay. A significant reduction in enzyme activity (21% of WT) and immunoreactive protein (29% of WT) for the Val73 variant allozyme was observed. Proteasome-mediated degradation and autophagy participated in the degradation of this variant allozyme. The chaperone proteins, BiP and GRP94, were upregulated after transfection with Val73 MME, suggesting protein misfolding, compatible with conclusions based on the MME X-ray crystal structure. Multiple novel polymorphisms of MME were identified in three ethnic groups. The Val73 variant allozyme displayed a significant decrease in MME protein quantity and activity, with degradation mediated by both proteasome and autophagy pathways. This polymorphism could have a significant effect on the metabolism of natriuretic peptides.

Dyssynchrony indices to predict response to cardiac resynchronization therapy: a comprehensive prospective single-center study

BACKGROUND

Whether mechanical dyssynchrony indices predict reverse remodeling (RR) or clinical response to cardiac resynchronization therapy (CRT) remains controversial. This prospective study evaluated whether echocardiographic dyssynchrony indices predict RR or clinical response after CRT.

METHODS AND RESULTS

Of 184 patients with heart failure with anticipated CRT who were prospectively enrolled, 131 with wide QRS and left ventricular ejection fraction <35% had 6-month follow-up after CRT implantation. Fourteen dyssynchrony indices (feasibility) by M-mode (94%), tissue velocity (96%), tissue Doppler strain (92%), 2D speckle strain (65% to 86%), 3D echocardiography (79%), and timing intervals (98%) were evaluated. RR (end-systolic volume reduction ≥15%) occurred in 55% and more frequently in patients without (71%) than in patients with (42%) ischemic cardiomyopathy (P=0.002). Overall, only M-mode, tissue Doppler strain, and total isovolumic time had a receiver operating characteristic area under the curve (AUC) greater than the line of no information, but none of these were strongly predictive of RR (AUC, 0.63 to 0.71). In nonischemic cardiomyopathy, no dyssynchrony index predicted RR. In ischemic cardiomyopathy, M-mode (AUC, 0.67), tissue Doppler strain (AUC, 0.79), and isovolumic time (AUC, 0.76) -derived indices predicted RR (P<0.05 for all), although the incremental value was modest. No indices predicted clinical response assessed by Minnesota Living with Heart Failure Questionnaire, 6-minute walk distance, and peak oxygen consumption.

CONCLUSIONS

These findings are consistent with the Predictors of Response to CRT study and do not support use of these dyssynchrony indices to guide use of CRT.

Mineralocorticoid accelerates transition to heart failure with preserved ejection fraction via "nongenomic effects"

BACKGROUND

Mechanisms promoting the transition from hypertensive heart disease to heart failure with preserved ejection fraction are poorly understood. When inappropriate for salt status, mineralocorticoid (deoxycorticosterone acetate) excess causes hypertrophy, fibrosis, and diastolic dysfunction. Because cardiac mineralocorticoid receptors are protected from mineralocorticoid binding by the absence of 11-beta hydroxysteroid dehydrogenase, salt-mineralocorticoid-induced inflammation is postulated to cause oxidative stress and to mediate cardiac effects. Although previous studies have focused on salt/nephrectomy in accelerating mineralocorticoid-induced cardiac effects, we hypothesized that hypertensive heart disease is associated with oxidative stress and sensitizes the heart to mineralocorticoid, accelerating hypertrophy, fibrosis, and diastolic dysfunction.

METHODS AND RESULTS

Cardiac structure and function, oxidative stress, and mineralocorticoid receptor-dependent gene transcription were measured in sham-operated and transverse aortic constriction (studied 2 weeks later) mice without and with deoxycorticosterone acetate administration, all in the setting of normal-salt diet. Compared with sham mice, sham plus deoxycorticosterone acetate mice had mild hypertrophy without fibrosis or diastolic dysfunction. Transverse aortic constriction mice displayed compensated hypertensive heart disease with hypertrophy, increased oxidative stress (osteopontin and NOX4 gene expression), and normal systolic function, filling pressures, and diastolic stiffness. Compared with transverse aortic constriction mice, transverse aortic constriction plus deoxycorticosterone acetate mice had similar left ventricular systolic pressure and fractional shortening but more hypertrophy, fibrosis, and diastolic dysfunction with increased lung weights, consistent with heart failure with preserved ejection fraction. There was progressive activation of markers of oxidative stress across the groups but no evidence of classic mineralocorticoid receptor-dependent gene transcription.

CONCLUSIONS

Pressure-overload hypertrophy sensitizes the heart to mineralocorticoid excess, which promotes the transition to heart failure with preserved ejection fraction independently of classic mineralocorticoid receptor-dependent gene transcription.

Regulation of circulating progenitor cells in left ventricular dysfunction

BACKGROUND

Reductions in numbers of circulating progenitor cells (CD34+ cell subsets) have been demonstrated in patients at risk for, or in the presence of, cardiovascular disease. The mediators of these reductions remain undefined. To determine whether neurohumoral factors might regulate circulating CD34+ cell subsets in vivo, we studied complementary canine models of left ventricular (LV) dysfunction.

METHODS AND RESULTS

A pacing model of severe LV dysfunction and a hypertensive renal wrap model in which dogs were randomized to receive deoxycorticosterone acetate (DOCA) were studied. Circulating CD34+ cell subsets including hematopoietic precursor cells (HPCs: CD34+/CD45(dim)/VEGFR2-) and endothelial progenitor cells (EPCs: CD34+/CD45-/VEGFR2+) were quantified. Additionally, the effect of mineralocorticoid excess on circulating progenitor cells in normal dogs was studied. The majority of circulating CD34+ cells expressed CD45dimly and did not express VEGFR2, consistent with an HPC phenotype. HPCs were decreased in response to pacing, and this decrease correlated with plasma aldosterone levels (Spearman rank correlation=-0.67, P=0.03). In the hypertensive renal wrap model, administration of DOCA resulted in decreased HPCs. No changes were seen in EPCs in either model. Normal dogs treated with DOCA exhibited a decrease in HPCs in peripheral blood but not bone marrow associated with decreased telomerase activity.

CONCLUSIONS

This is the first study to demonstrate that mineralocorticoid excess, either endogenous or exogenous, results in reduction in HPCs. These data suggest that mineralocorticoids may induce accelerated senescence of progenitor cells, leading to their reduced survival and decline in numbers.

Exercise hemodynamics enhance diagnosis of early heart failure with preserved ejection fraction

BACKGROUND

When advanced, heart failure with preserved ejection fraction (HFpEF) is readily apparent. However, diagnosis of earlier disease may be challenging because exertional dyspnea is not specific for heart failure, and biomarkers and hemodynamic indicators of volume overload may be absent at rest.

METHODS AND RESULTS

Patients with exertional dyspnea and ejection fraction >50% were referred for hemodynamic catheterization. Those with no significant coronary disease, normal brain natriuretic peptide assay, and normal resting hemodynamics (mean pulmonary artery pressure <25 mm Hg and pulmonary capillary wedge pressure [PCWP] <15 mm Hg) (n=55) underwent exercise study. The exercise PCWP was used to classify patients as having HFpEF (PCWP ≥25 mm Hg) (n=32) or noncardiac dyspnea (PCWP <25 mm Hg) (n=23). At rest, patients with HFpEF had higher resting pulmonary artery pressure and PCWP, although all values fell within normal limits. Exercise-induced elevation in PCWP in HFpEF was confirmed by greater increases in left ventricular end-diastolic pressure and was associated with blunted increases in heart rate, systemic vasodilation, and cardiac output. Exercise-induced pulmonary hypertension was present in 88% of patients with HFpEF and was related principally to elevated PCWP, as pulmonary vascular resistances dropped similarly in both groups. Exercise PCWP and pulmonary artery systolic pressure were highly correlated. An exercise pulmonary artery systolic pressure ≥45 mm Hg identified HFpEF with 96% sensitivity and 95% specificity.

CONCLUSIONS

Euvolemic patients with exertional dyspnea, normal brain natriuretic peptide, and normal cardiac filling pressures at rest may have markedly abnormal hemodynamic responses during exercise, suggesting that chronic symptoms are related to heart failure. Earlier and more accurate diagnosis using exercise hemodynamics may allow better targeting of interventions to treat and prevent HFpEF progression.

The prognostic value of N-terminal pro-B-type natriuretic peptide for death and cardiovascular events in healthy normal and stage A/B heart failure subjects

OBJECTIVES

Our objective was to determine the prognostic value of plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) for death and cardiovascular events among subjects without risk factors for heart failure (HF), which we term healthy normal.

BACKGROUND

Previous studies report that plasma NT-proBNP has prognostic value for cardiovascular events in the general population even in the absence of HF. It is unclear if NT-proBNP retains predictive value in healthy normal subjects.

METHODS

We identified a community-based cohort of 2,042 subjects in Olmsted County, Minnesota. Subjects with symptomatic (stage C/D) HF were excluded. The remaining 1,991 subjects underwent echocardiography and NT-proBNP measurement. We further defined healthy normal (n = 703) and stage A/B HF (n = 1,288) subgroups. Healthy normal was defined as the absence of traditional clinical cardiovascular risk factors and echocardiographic structural cardiac abnormalities. Subjects were followed for death, HF, cerebrovascular accident, and myocardial infarction with median follow-up of 9.1, 8.7, 8.8, and 8.9 years, respectively.

RESULTS

NT-proBNP was not predictive of death or cardiovascular events in the healthy normal subgroup. Similar to previous reports, in stage A/B HF, plasma NT-proBNP values greater than age-/sex-specific 80th percentiles were associated with increased risk of death, HF, cerebrovascular accident, and myocardial infarction (p < 0.001 for all) even after adjustment for clinical risk factors and structural cardiac abnormalities.

CONCLUSIONS

These findings do not support the use of NT-proBNP as a cardiovascular biomarker in healthy normal subjects and have important implications for NT-proBNP-based strategies for early detection and primary prevention of cardiovascular disease.