Authors (including presenting author) :
Wong KL (1), Koo E (2), Au KL (1), Cheng KY (1), Chow YM (1)
Kong YL (1), Ng LK (1), Lee MY (1), Fan YYK (1)
Affiliation :
(1) Cardiac Medical Unit, Grantham Hospital
(2) Clinical Pathology Laboratory, Grantham Hospital
Introduction :
N-terminal pro-B-type natriuretic peptide (NTproBNP) is increased in heart failure as ventricular cells are recruited to secret in response to high ventricular filling pressures with myocardial stress. According to 2017 ACC/AHA/HFSA Focused Update of the 2013 ACCF/AHA Guideline for the Management of Heart Failure, measurement of baseline levels of natriuretic peptide biomarkers on admission to the hospital is assigned as Class IA recommendation to help establish prognosis in acute decompensated heart failure (ADHF). As a tertiary referral center, end stage heart failure patients are being referred to Grantham Hospital (GH) for management of advanced HF and evaluation for heart transplantation. The Heart Transplant Program in HKWC is the first to utilize NTproBNP to help establish prognosis for AHF patients.
Objectives :
To align with international heart failure guideline recommendation in assessing the severity and as prognostic marker for ADHF and /or end stage HF patients admitted to Cardiac Medical Unit (CMU) with the intention of improved outcomes of advanced HF.
Methodology :
Plasma NT-proBNP are tested using point-of-care assay (AQT90Flex Analyzer) in GH with proper operating procedures and quality control in collaboration with Clinical Pathology Laboratory. From October 2016 to December 2019, a total of 340 patients were studied. NT-proBNP was checked when patients were first admitted as in-patient for advanced heart failure therapy. A second assay was also performed as reassessment for clinical progress. NT-proBNP values were categorized according to quartiles. The absolute value and percentage of changes between admission and reassessment values were calculated and the relationship in association with primary end-points was assessed. Primary end-point was defined as all-cause mortality, heart transplantation and/or left ventricular assist devices surgery (LVAD).
Result & Outcome :
During the period studied, a total of 582 NT-proBNP tests was done on 340 heart failure patients. Their mean age was 56±14 years and 65% were men. Overall mean baseline NT-proBNP was 5904 ± 8239 pg/ml (ranged from 70 to >35000 pg/ml; Normal level excluding heart failure is defined as < 300 pg/ml).
The occurrence of primary end point was 32.1% and increased with each quartile of NT-proBNP levels: 9%, 28%, 43% and 54% in patients with NT-proBNP levels < 1000pg/ml,1001-3000 pg/ml, 3001-9000 pg/ml and >9000 pg/ml respectively. There were overall mortality of 62 patients (18.2%).
Second (2nd) NT proBNP level was checked among 123 patients (36.2%) with a mean interval of 191 days from first NT-proBNP. Patients who reached primary end-points had significant higher 2nd NT-proBNP (mean 2nd NT-proBNP 9,327 vs 3,001 p=0.001). When comparing mortality rate, those who died by end of study period showed a significant higher 2nd NT-proBNP level when compared with those who survived (mean 2nd NT-proBNP 12,563 vs 3,601 p< 0.001) as well as significant higher absolute rise from baseline (change in NT-proBNP +1548 vs -3246 p=0.016).
The GH Advanced Heart Failure Clinical Pathway was reviewed and plasma NTproBNP has since been incorporated onto the pathway as prognostic guide with intention of improved outcome of advanced HF.
This project has demonstrated that plasma NT-proBNP level was associated with significantly higher mortality and morbidity in patients with advanced heart failure. By identifying high risk heart failure patients in clinical practice, more intensifying therapy and early initiation of advanced heart failure treatment including mechanical circulatory support can be established.
