Invasive and Non-invasive Monitoring of Volume Status in HF
Heart failure (HF) represents a major health and economic burden worldwide. In spite of best current therapy, HF progresses with unpredictable episodes of deterioration that often require hospitalisation. These episodes are often preceded by accumulation or redistribution of fluid causing haemodynamic overload on the heart. Remote and telemonitoring of the HF patient, assessing symptoms and signs, thoracic impedance derived fluid status follow-up or direct haemodynamic measurements with chronic implanted devices are presently under investigation for the potential to detect impending HF decompensation early. The current evidence for volume status monitoring in HF using those novel management strategies is reviewed.
Heart failure (HF) represents a major health and economic burden which is increasing with the ageing of populations around the world. In the USA, over 5.7 million people are currently estimated to live with HF. In Europe, over 15 million people are estimated to have HF, and with a similar prevalence of asymptomatic left ventricular (LV) dysfunction, approximately 4% of the European population has either HF or LV dysfunction. Despite advances in pharmacological and other therapies, rates for HF related hospital admission have not substantially decreased and represent a major driver for healthcare expenditure. Recent data indicate that inhospital care accounts for approximately 60% of total HF costs. Rehospitalisation for worsening HF predicts adverse prognosis, especially in the elderly, and is often initiated by intrathoracic fluid overload leading to symptomatic pulmonary congestion. The vast majority of patients with acute decompensated HF (ADHF) has underlying chronic HF. Our current understanding of mechanisms contributing in ADHF is still insufficient but altered LV loading conditions and hypervolaemia are likely important contributing factors. Intrathoracic fluid accumulation frequently precedes hospital admission. Conceptually, continuous monitoring of fluid status in HF patients could aid identification of volume overload, thus providing an opportunity to intervene at an early stage and possibly avert hospital admission for ADHF. However, early clinical detection of ADHF is challenging. Haemodynamic disturbances underlying ADHF may start weeks before the actual onset of typical HF symptoms such as fatigue, body weight gain or shortness of breath. Moreover, these are common, especially in the elderly without HF, and may be overlooked both by doctors and patients themselves. Diagnostic tools widely used in HF workup such as chest x-ray, cardiac catheterisation and conventional echocardiography are of limited use in determining the individual patient's fluid status.
Biomarkers in the assessment of clinical status of HF have emerged over the past two decades and are now routinely measured in various clinical settings. While the role of B type natriuretic peptide (BNP) in diagnosis as well as prognostification of HF is well established, there has been ongoing debate regarding its role as a guide to monitoring and adjustment of HF therapy. Recent meta-analyses of major randomised controlled trials (RCTs) in the field have suggested a mortality benefit in patients with monitored BNP, presumably due to enhanced use of drugs such as angiotensin converting enzyme inhibitors (ACEI) and β blockers in the cohort exhibiting biomarker increases. Another report concluded that N terminal BNP guided HF specialist care in addition to home based nurse care was cost effective and cheaper than standard care. There are conflicting data as to whether BNP guided HF care reduces rehospitalisation rates. BNPs may not be sensitive enough tools to detect rapidly decompensating HF. In ADHF, acute changes in LV filling pressures will likely not be reflected by simultaneous changes in NPs due to their long half-lives, thus limiting their clinical utility in that setting. Furthermore, patient characteristics (ie, age, gender, body weight) may influence plasma levels of BNP and other NPs, making interpretation even more difficult.
Therefore, novel strategies to more precisely assess and monitor fluid status in HF have been explored over recent years. Some of those developments seem to hold promise in improving early detection of which patients will likely be readmitted for ADHF, with the potential to intervene early. Bringing down HF hospitalisation rates may not only improve patient quality of life but also reduce longer term clinical outcomes and alleviate the enormous HF related cost to society.
This review seeks to summarise current knowledge on integrating fluid status monitoring into the overall management of HF patients.
Abstract and Introduction
Abstract
Heart failure (HF) represents a major health and economic burden worldwide. In spite of best current therapy, HF progresses with unpredictable episodes of deterioration that often require hospitalisation. These episodes are often preceded by accumulation or redistribution of fluid causing haemodynamic overload on the heart. Remote and telemonitoring of the HF patient, assessing symptoms and signs, thoracic impedance derived fluid status follow-up or direct haemodynamic measurements with chronic implanted devices are presently under investigation for the potential to detect impending HF decompensation early. The current evidence for volume status monitoring in HF using those novel management strategies is reviewed.
Introduction
Heart failure (HF) represents a major health and economic burden which is increasing with the ageing of populations around the world. In the USA, over 5.7 million people are currently estimated to live with HF. In Europe, over 15 million people are estimated to have HF, and with a similar prevalence of asymptomatic left ventricular (LV) dysfunction, approximately 4% of the European population has either HF or LV dysfunction. Despite advances in pharmacological and other therapies, rates for HF related hospital admission have not substantially decreased and represent a major driver for healthcare expenditure. Recent data indicate that inhospital care accounts for approximately 60% of total HF costs. Rehospitalisation for worsening HF predicts adverse prognosis, especially in the elderly, and is often initiated by intrathoracic fluid overload leading to symptomatic pulmonary congestion. The vast majority of patients with acute decompensated HF (ADHF) has underlying chronic HF. Our current understanding of mechanisms contributing in ADHF is still insufficient but altered LV loading conditions and hypervolaemia are likely important contributing factors. Intrathoracic fluid accumulation frequently precedes hospital admission. Conceptually, continuous monitoring of fluid status in HF patients could aid identification of volume overload, thus providing an opportunity to intervene at an early stage and possibly avert hospital admission for ADHF. However, early clinical detection of ADHF is challenging. Haemodynamic disturbances underlying ADHF may start weeks before the actual onset of typical HF symptoms such as fatigue, body weight gain or shortness of breath. Moreover, these are common, especially in the elderly without HF, and may be overlooked both by doctors and patients themselves. Diagnostic tools widely used in HF workup such as chest x-ray, cardiac catheterisation and conventional echocardiography are of limited use in determining the individual patient's fluid status.
Biomarkers in the assessment of clinical status of HF have emerged over the past two decades and are now routinely measured in various clinical settings. While the role of B type natriuretic peptide (BNP) in diagnosis as well as prognostification of HF is well established, there has been ongoing debate regarding its role as a guide to monitoring and adjustment of HF therapy. Recent meta-analyses of major randomised controlled trials (RCTs) in the field have suggested a mortality benefit in patients with monitored BNP, presumably due to enhanced use of drugs such as angiotensin converting enzyme inhibitors (ACEI) and β blockers in the cohort exhibiting biomarker increases. Another report concluded that N terminal BNP guided HF specialist care in addition to home based nurse care was cost effective and cheaper than standard care. There are conflicting data as to whether BNP guided HF care reduces rehospitalisation rates. BNPs may not be sensitive enough tools to detect rapidly decompensating HF. In ADHF, acute changes in LV filling pressures will likely not be reflected by simultaneous changes in NPs due to their long half-lives, thus limiting their clinical utility in that setting. Furthermore, patient characteristics (ie, age, gender, body weight) may influence plasma levels of BNP and other NPs, making interpretation even more difficult.
Therefore, novel strategies to more precisely assess and monitor fluid status in HF have been explored over recent years. Some of those developments seem to hold promise in improving early detection of which patients will likely be readmitted for ADHF, with the potential to intervene early. Bringing down HF hospitalisation rates may not only improve patient quality of life but also reduce longer term clinical outcomes and alleviate the enormous HF related cost to society.
This review seeks to summarise current knowledge on integrating fluid status monitoring into the overall management of HF patients.
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