Performance of BNP and NT-proBNP for diagnosis of heart failure in primary care patients: a systematic review

National and international guidelines have been published recommending the use of natriuretic peptides as an aid to the diagnosis of heart failure (HF) in acute settings; however, few specific recommendations exist for governing the use of these peptides in primary care populations. To summarize the available data relevant to the diagnosis of HF in primary care patient population, we systematically reviewed the literature to identify original articles that investigated the diagnostic accuracy of B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) in primary care settings. The search yielded 25,864 articles in total: 12 investigating BNP and 20 investigating NT-proBNP were relevant to our objective and included in the review. QUADAS-2 and GRADE were used to assess the quality of the included articles. Diagnostic data were pooled based on three cutpoints: lowest and optimal, as chosen by study authors, and manufacturers’ suggested. The effect of various determinants (e.g., age, gender, BMI, and renal function) on diagnostic performance was also investigated. Pooled sensitivity and specificity of BNP and NT-proBNP using the lowest [0.85 (sensitivity) and 0.54 (specificity)], optimal (0.80 and 0.61), and manufacturers’ (0.74 and 0.67) cutpoints showed good performance for diagnosing HF. Similar performance was seen for NT-proBNP: lowest (0.90 and 0.50), optimal (0.86 and 0.58), and manufacturers’ (0.82 and 0.58) cutpoints. Overall, we rated the strength of evidence as high because further studies will be unlikely to change the estimates diagnostic performance.     

Incremental value of natriuretic peptide measurement in acute decompensated heart failure (ADHF): a systematic review

The aim of this systematic review was to determine whether B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) independently add incremental value for predicting mortality and morbidity in patients with acute decompensated heart failure (ADHF). Medline^®, Embase?, AMED, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and CINAHL were searched from 1989 to June 2012. We also searched reference lists of included articles, systematic reviews, and the gray literature. Studies were screened for eligibility criteria and assessed for risk of bias. Data were extracted on study design, population demographics, assay cutpoints, prognostic risk prediction model covariates, statistical methods, outcomes, and results. From 183 citations, only seven studies (5 BNP and 2 NT-proBNP) considered incremental value in ADHF subjects admitted to acute care centers. Admission assay levels and length of follow-up varied for BNP studies (31 days to 12 months) and for NT-proBNP studies (25–82 months). All studies presented at least one estimate of incremental value of BNP/NT-proBNP relative to the base prognostic model. Using discrimination or likelihood statistics, these studies consistently showed that BNP or NT-proBNP increased model performance. Three studies used reclassification and model validation computations to establish incremental value; these studies showed less consistency with respect to added value. In conclusion, the literature assessing incremental value of BNP/NT-proBNP in ADHF populations is limited to seven studies evaluating only mortality outcomes and at moderate risk of bias. Although there were differences in the base risk prediction models, assay cutpoints, and lengths of follow-up, there was consistency in BNP/NT-proBNP adding incremental value in prediction models in ADHF patients.     

Assessment of cardiac autonomic functions by heart rate recovery,heart rate variability and QT dynamicity parameters in patients with acromegaly

Cardiovascular complications are the most common causes of morbidity and mortality in acromegaly. However, there is little data regarding cardiac autonomic functions in these patients. Herein, we aimed to investigate several parameters of cardiac autonomic functions in patients with acromegaly compared to healthy subjects. We enrolled 20 newly diagnosed acromegalic patients (55 % female, age:45.7 ± 12.6 years) and 32 age- and gender-matched healthy subjects. All participants underwent 24 h Holter recording. Heart rate recovery (HRR) indices were calculated by subtracting 1st, 2nd and 3rd minute heart rates from maximal heart rate. All patients underwent heart rate variability (HRV) and QT dynamicity analysis. Baseline characteristics were similar except diabetes mellitus and hypertension among groups. Mean HRR1 (29.2 ± 12.3 vs 42.6 ± 6.5, p = 0.001), HRR2 (43.5 ± 15.6 vs 61.1 ± 10.8, p = 0.001) and HRR3 (46.4 ± 16.2 vs 65.8 ± 9.8, p = 0.001) values were significantly higher in control group. HRV parameters as, SDNN [standard deviation of all NN intervals] (p = 0.001), SDANN [SD of the 5 min mean RR intervals] (p = 0.001), RMSSD [root square of successive differences in RR interval] (p = 0.001), PNN50 [proportion of differences in successive NN intervals >50 ms] (p = 0.001) and high-frequency [HF] (p = 0.001) were significantly decreased in patients with acromegaly; but low frequency [LF] (p = 0.046) and LF/HF (p = 0.001) were significantly higher in acromegaly patients. QTec (p = 0.009), QTac/RR slope (p = 0.017) and QTec/RR slope (p = 0.01) were significantly higher in patients with acromegaly. Additionally, there were significant negative correlation of disease duration with HRR2, HRR3, SDNN, PNN50, RMSSD, variability index. Our study results suggest that cardiac autonomic functions are impaired in patients with acromegaly. Further large scale studies are needed to exhibit the prognostic significance of impaired autonomic functions in patients with acromegaly.