St. Vincent's Screening To Prevent Heart Failure Study

A large proportion of the population has substantial left ventricular dysfunction (LVD) and do not have symptoms (Stage B heart failure). For many of these patients, if identified and treated appropriately, it is possible to prevent the subsequent development of heart failure (HF). Although the current gold standard for detection of LVD is echocardiography, it is expensive and impractical for mass screening.

Natriuretic peptides are attractive candidates for screening populations for asymptomatic LVD particularly because of high negative predictive values. Furthermore, some studies have shown that, in the right setting, screening with natriuretic peptides might prove cost effective in combination with echocardiography for patients with elevated levels.

However, in common with many accepted screening strategies, there are no randomised studies which show that screening the population with natriuretic peptides for asymptomatic LVF alters the natural history of the condition.

From a large, community based cardiovascular risk screening programme including more than 13,000 patients, patients in the catchment area of St Vincent's University Hospital are invited to participate in the STOP-HF study. The objective of this work is to determine whether or not using natriuretic peptide screening in conjunction with specialist follow-up will reduce the prevalence and severity of LVD in a well-defined, at-risk, primary care population. It also aims to: evaluate the natural history of natriuretic peptides over time in this population; to clarify optimal screening cut-offs for the detection of LVD; to evaluate the clinical, pharmacological, biochemical, genetic and proteomic determinants of natriuretic peptides in this setting; to determine whether the clinical benefits of the STOP HF screening programme, if any, are cost effective.

The study design is prospective, randomised and parallel group.

The primary endpoint is the prevalence and severity LVD after 5 years of follow up. Secondary endpoints include: the natural history of natriuretic peptides; the relationship between natriuretic peptides and severity of LVD, death, hospital admissions; clinical, demographic, biochemical, pharmacological, genomic, proteomic, metabolomic determinants of natriuretic peptides; screening cost-effectiveness.

Participants who fulfill entry criteria at baseline will sign an informed consent and will be randomised onto the Usual Care or Intervention Care arm of the study. Usual care is defined as continued management of the patient by the primary care services using standard risk factor monitoring and intervention strategies. Intervention Care is defined as a collaborative cardiovascular management between primary care and specialist hospital based services. All participants will receive an intensive education session from a cardiovascular nurse on their risk factors and advice on healthy dietary and lifestyle habits.

There will be 2 years of enrollment with annual review and 5 years of follow-up to the primary endpoint. Permission has been received to extend the follow up period to 10 years. Regardless of randomisation, all patients receive full clinical and laboratory assessment at baseline and on completion of the STOP HF study (year 5). Additionally, all participants will receive echocardiography assessment during and at the conclusion of the study.

Data collection:

Data will be collected on all participants regarding their medical history and current medications. The source of data collection will be from medical records kept at the primary care practices and from patient interview. All participants will receive a booklet in which they will be asked to record any visits to their primary care practitioner, alterations in medications, new diagnoses and hospital admissions. Local hospital discharge records will be screened to detect any events throughout the course of the study.

Clinical Assessment:

At annual intervals, the cardiovascular research nurse will conduct clinical assessments on all participants including weight, abdominal girth measurement, blood pressure (triplicate measurements while lying in supine position), heart rate and observe for evidence of limb oedema. The nurse will also question the participants to investigate for symptoms of dyspnoea, angina, palpitations, orthopnoea, palpitations and fatigue.

Blood sampling and handling:

Peripheral venous blood samples will be drawn on all participants at annual intervals. Samples to assess natriuretic peptides will be drawn into vacutainers containing EDTA and samples to assess renal function, collagen turnover and lipid profile will be collected in vacutainers containing lithium heparin. BNP and Lipid profile assessment will be analysed using point of care meters, Biosite (Triage, USA) and Cholestech respectively. Each of the remaining samples will be centrifuged for 10 minutes and the serum will be then aliquoted and stored at -80°C before analysis of biochemical, genomic, proteomic and metabolomic markers.

Echocardiographic Doppler analysis:

Two-dimensional echocardiographic imaging, targeted M-mode and Doppler ultrasound measurements will be obtained in each patient. M-mode measurements are taken according to the guidelines laid down by the American Society of Echocardiography. All echocardiographic data will represent the mean of 3 measurements on different cardiac cycles. It is the aim of the STOP HF investigators that a single observer will conduct all measurements, recording archive images in a blinded fashion.