Heart failure in primary health care : special emphasis on natriuretic peptides in the elderly

• Background: This thesis focuses on heart failure among elderly patients in the community who usually are not included in studies on heart failure. The heart failure syndrome is an increasing problem in Western society. Severe heart failure is often easy to diagnose compared with light to moderate heart failure, which is more frequent in patients in the community,Doppler echocardiography is the most commonly used method to objectively verify an abnormal cardiac function, mostly the systolic function. One goal of this thesis was to evaluate both the systolic and diastolic functions. Another goal was a study of the possible utility of the B-type natriuretic peptide, BNP (brain natriuretic peptide), and the amino terminal fragment of its precursor, proBNP (N-terminal proBNP) as tools in the diagnosis of heart failure in elderly patients.Methods: In a primary health care setting, 510 elderly patients (age range 65-82 years) with symptoms and signs possibly associated with heart failure were examined concerning patient history, ongoing pharmacological treatment, clinical examination, chest x-ray, electrocardiogram, Doppler echo cardiography, and selected biochemical measurements of blood samples. Additionally, the natriuretic peptide BNP and the aminoterminal fragment of proBNP were analyzed for a possible influence of gender, age, impaired cardiac function assessed using Doppler echocardiography, other diseases, and phannacological treatment. We followed our study population for six years, carefully registering mortality with death certificates. This information was used in analyzing the risk of cardiovascular death based on Cox proportional hazard regression. We present a model for estimating the risk of cardiovascular death in the individual patient.Results: Almost half of our study population [mean age 73 (SD 6) years] with symptoms of possible heart failure had signs of impaired cardiac function on Doppler echocardiography. Half of these individuals had isolated impairment of the diastolic function. Almost two thirds of the elderly patients who had an ejection fraction of less than 40% did not receive treatment with ACE inhibitors, one of the cornerstones in the treatment of heart failure.BNP and N-terminal proBNP were equally effective in detecting impaired cardiac function. As a response to increased filling pressure they probably provide earlier information on the haemodynamic situation than Doppler echocardiography does.In these elderly patients, functional class (NYHA class III: 7 times increased risk), in vivo examination by Doppler echo cardiography (EF<30%: 8 times increased risk) and the in vitro measurement of plasma BNP (>27.8 pmol/L: 11 times increased risk) and N-terminal proBNP (>109 pmol/L: 7 times increased risk) could be used as prognostic determinants in assessing the risk of cardiovascular death.Conclusion: The results indicate that a focused patient history and clinical examination provides important information that is often sufficient for the prognostic evaluation of a patient with heart failure symptoms. Additional information may be obtained with Doppler echo cardiographic examination and measurement of plasma BNP or N-terminal proBNP. The relationship between BNPIN-terminal proBNP concentration and risk of cardiovascular death may be analysed to define decision limits for the concentrations of these peptides as regards further diagnostic procedures and/or phannaceutical treatment.

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