Medicine (St Vincent's) - Theses
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ItemIdentification of structural heart disease in a high risk, asymptomatic community cohort - the SCREEN-HF Study( 2015)The development of symptomatic heart failure portends a poor prognosis, even in the current era where many effective heart failure therapies are available. Identification of subjects at particularly elevated risk of heart failure, including those with classic heart failure risk factors or underlying structural heart disease, could facilitate a more preventative approach to this condition. However, effective risk stratification tools have not yet been developed and the potential role of screening tools such as clinical risk prediction models and cardiac biomarkers requires further evaluation. The SCReening Evaluation for the Evolution of New Heart Failure (SCREEN-HF) study was designed to determine whether serum N-terminal B-type natriuretic peptide (NT-proBNP), a cardiac biomarker associated with increases in myocardial wall stress, could be used as an effective risk stratification tool in an older, asymptomatic community cohort selected by heart failure risk factors. The initial cross-sectional component of the study, with which this thesis is concerned, was developed to assess the ability of serum NT-proBNP to predict the presence of significant structural heart disease associated with an elevated risk of incident heart failure. However, longitudinal follow up in of the SCREEN-HF cohort will later assess whether serum NT-proBNP levels are effective in predicting the onset of symptomatic heart failure and other cardiovascular events. Structural heart disease was found to be common within the high risk SCREEN-HF cohort, with significant echocardiographic abnormalities detected in approximately one in four subjects. Serum NT-proBNP quintile was associated with structural heart disease, particularly left ventricular systolic dysfunction with a reduced ejection fraction. However the poor test performance characteristics of serum NT-proBNP, even at optimized cut-points, suggest that it would be an inadequate tool for detecting structural heart disease in this population, resulting in an unacceptably high number of missed cases of structural heart disease. The poor predictive capacity of serum NT-proBNP for structural heart disease in the SCREEN-HF cohort may relate to an increased noise-to-signal ratio in the setting of low absolute serum NT-proBNP values, and also to the narrower spectrum of cardiovascular risk in a population selected by heart failure risk factors. In contrast, transthoracic echocardiography was able to detect clinically significant structural heart disease in a quarter of subjects in this selected population. The high prevalence of echocardiographic abnormalities, associated with an increased risk of incident heart failure, suggests that echocardiographic screening, though more expensive and resource-intensive than measurement of serum NT-proBNP levels, may be justified in a similarly selected, high-risk population.