B-type natriuretic peptide in the evaluation and management of dyspnoea in primary care.

OBJECTIVES: The rapid and accurate diagnosis of heart failure in primary care is a major unmet clinical need. We evaluated the additional use of B-type natriuretic peptide (BNP) levels. DESIGN: A randomized controlled trial. SETTING: Twenty-nine primary care physicians in Switzerland and Germany coordinated by the University Hospital Basel, Switzerland. SUBJECTS: A total of 323 consecutive patients presenting with dyspnoea. INTERVENTIONS: Assignment in a 1 : 1 ratio to a diagnostic strategy including point-of-care measurement of BNP (n = 163) or standard assessment without BNP (n = 160). The total medical cost at 3 months was the primary end-point. Secondary end-points were diagnostic certainty, time to appropriate therapy, functional capacity, hospitalization and mortality. The final diagnosis was adjudicated by a physician blinded to the BNP levels. RESULTS: Heart failure was the final diagnosis in 34% of patients. The number of hospitalizations, functional status and total medical cost at 3 months [median $1655, interquartile range (IQR), 850-3331 vs. $1541, IQR 859-2827; P = 0.68] were similar in both groups. BNP increased diagnostic certainty as defined by the need for further diagnostic work-up (33% vs. 45%; P = 0.02) and accelerated the initiation of the appropriate treatment (13 days vs. 25 days; P = 0.01). The area under the receiver-operating characteristics curve for BNP to identify heart failure was 0.87 (95% confidence interval, 0.81-0.93). CONCLUSIONS: The use of BNP levels in primary care did not reduce total medical cost, but improved some of the secondary end-points including diagnostic certainty and time to initiation of appropriate treatment.

Sensitive cardiac troponin in the diagnosis and risk stratification of acute heart failure.

BACKGROUND: The aim of our study was to investigate the diagnostic and prognostic value of a sensitive cardiac troponin I (s-cTnI) assay in patients with acute heart failure (AHF). METHODS: Sensitive cardiac troponin I was measured in 667 consecutive patients at presentation to the emergency department with acute dyspnoea. Three s-cTnI strata were predefined: below the limit of detection (<0.01 µg L(-1) , undetectable), detectable but still within the normal range (0.01-0.027 µg L(-1) ) and increased (≥0.028 µg L(-1) , ≥99th percentile). The final diagnosis was adjudicated by two independent cardiologists blinded to the s-cTnI levels. Median follow-up in patients with AHF was 371 days. RESULTS: Levels of s-cTnI were higher in patients with AHF (n = 377, 57%) compared to patients with noncardiac causes of acute dyspnoea (median 0.02 vs. <0.01 µg L(-1) , P < 0.001). In patients with AHF, in-hospital mortality increased with increasing s-cTnI in the three strata (2%, 5% and 14%, P < 0.001). One-year mortality also increased with increasing s-cTnI (21%, 33% and 47%, P < 0.001). s-cTnI remained an independent predictor of 1-year mortality [adjusted odds ratio 1.03 for each increase of 0.1 µg L(-1) , 95% confidence interval (CI) 1.02-1.05, P < 0.001] after adjustment for other risk factors including B-type natriuretic peptide. The net reclassification improvement was 68% (P < 0.001), and absolute integrated discrimination improvement was 0.18 (P < 0.001). The diagnostic accuracy of s-cTnI for the diagnosis of AHF as quantified by the area under the receiver operating characteristic curve was 0.78 (95% CI, 0.75-0.82). CONCLUSIONS: Sensitive cardiac troponin I is a strong predictor of short- and long-term prognosis in AHF that helps to reclassify patients in terms of mortality risk. Detectable levels of s-cTnI, even within the normal range, are independently associated with mortality.

Interleukin family member ST2 and mortality in acute dyspnoea.

OBJECTIVES: The study objective was to investigate the prognostic utility and patient-specific characteristics of ST2 (suppression of tumorigenicity 2), assessed with a novel sensitive assay. BACKGROUND: Suppression of tumorigenicity 2 signalling has been shown to be associated with death in cardiac and pulmonary diseases. DESIGN/SUBJECTS: In an international multicentre cohort design, we prospectively enrolled 1091 patients presenting with acute dyspnoea to the emergency department (ED). ST2 was measured in a blinded fashion using a novel assay and compared to B-type natriuretic peptide (BNP) and NT-proBNP. The primary end-point was mortality within 30 days and 1 year. The prognostic value of ST2 was evaluated in comparison and in addition to BNP and NT-proBNP. RESULTS: Suppression of tumorigenicity 2 concentrations was higher amongst decedents than among survivors (median 85 vs. 43 U mL⁻¹, P < 0.001) and also higher in patients with impaired left ventricular ejection fraction (LVEF) when compared with preserved LVEF (P < 0.001). In receiver operator characteristics analysis, the area under the curve (AUC) for ST2, BNP and NT-proBNP to predict 30-day and 1-year mortality were 0.76, 0.63 and 0.71, and 0.72, 0.71 and 0.73, respectively. The combinations of ST2 with BNP or NT-proBNP improved prediction of mortality provided by BNP or NT-proBNP alone. After multivariable adjustment, ST2 values above the median (50 U mL⁻¹) significantly predicted 1-year mortality (HR 2.3, P < 0.001). CONCLUSION: In patients presenting to the ED with acute dyspnoea, ST2 is a strong and independent predictor of 30-day and 1-year mortality and might improve risk stratification already provided by BNP or NT-proBNP.

Use of B-type natriuretic peptide to predict blood pressure improvement after percutaneous revascularisation for renal artery stenosis.

OBJECTIVES: The purpose of this study was to evaluate the utility of B-type natriuretic peptide (BNP) to predict blood pressure (BP) response in patients with renal artery stenosis (RAS) after renal angioplasty and stenting (PTRA). METHODS: In 120 patients with RAS and hypertension referred for PTRA, 24-h ambulatory BP recordings were obtained before and 6 months after intervention. BNP was measured before, 1 day and 6 months after PTRA. RESULTS: BP improved in 54% of patients. Median BNP levels pre-intervention were 97 pg ml(-1) (interquartile range (IQR) 35-250) and decreased significantly within 1 day of PTRA to 62 pg ml(-1) (IQR 24-182) (p < 0.001), remaining at 75 pg ml(-1) (IQR 31-190) at 6 months. The area under the receiver operating curve for pre-intervention BNP to predict BP improvement was 0.57 (95% confidence interval (CI) 0.46-0.67). Pre-intervention BNP >50 pg ml(-1) was seen in 79% of patients with BP improvement compared with 56% in patients without improvement (p = 0.01). In a multivariate logistic regression analysis, BNP >50 pg ml(-1) was significantly associated with BP improvement (odds ratio (OR) 4.0, 95% CI 1.2-13.2). CONCLUSIONS: BNP levels are elevated in patients with RAS and decrease after revascularisation. Although BNP does not seem useful as a continuous variable, pre-interventional BNP >50 pg ml(-1) may be helpful to identify patients in whom PTRA will improve BP.