The efficacy of the exercise treadmill test in patients with mild cardiovascular risk in a regional New Zealand population
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Other Title
Authors
Cheeseman, Sarah
Author ORCID Profiles (clickable)
Degree
Master of Nursing
Grantor
Eastern Institute of Technology
Date
2014
Supervisors
Marshall, Bob
Searle, Judy
Searle, Judy
Type
Masters Thesis
Ngā Upoko Tukutuku (Māori subject headings)
Keyword
New Zealand
patients
chest pain clinic
exercise treadmill test
cardiovascular risk factors
coronary artery disease (CAD)
typical symptoms
atypical symptoms
coronary angiography
patients
chest pain clinic
exercise treadmill test
cardiovascular risk factors
coronary artery disease (CAD)
typical symptoms
atypical symptoms
coronary angiography
ANZSRC Field of Research Code (2020)
Citation
Cheeseman, S. M. (2014). The efficacy of the exercise treadmill test in patients with mild cardiovascular risk in a regional New Zealand population. (Unpublished document submitted in partial fulfilment of the requirements for the degree of Master of Nursing). Eastern Institute of Technology (EIT), New Zealand.
Abstract
BACKGROUND
The purpose of this study was to investigate the efficacy of the exercise treadmill test in patients with mild cardiovascular risk in a regional population in New Zealand. Exercise treadmill tests are a valuable non-invasive tool to assist in the diagnosis of coronary artery disease and have been used for many years. There has been continued debate over the accuracy of the exercise treadmill test in the patient with mild cardiovascular disease due to the potential for false positive results and the subsequent cost implications further testing incurs in this group. Despite this, exercise treadmill testing remains a commonly used test in this cohort.
A large proportion of patients with mild cardiovascular risk are seen in the researcher's chest pain clinic and undergo assessment for coronary artery disease using exercise treadmill testing. Due to the current fiscal and resource constraints in the public health system it is important to know that local resources are being utilised in a safe, effective and efficient way. This research has been undertaken to understand the efficacy of the exercise treadmill test in patients with mild cardiovascular risk within a regional New Zealand hospital. It comprises a review of the literature associated with exercise stress testing, the methodology used to complete the research, the results, and finally the implications of these including limitations and recommendations.
AIM
To determine the efficacy of the exercise treadmill test in predicting the presence of coronary artery disease in patients with mild cardiovascular risk in a regional New Zealand population.
DESIGN
A quantitative, retrospective audit was completed in an outpatient population, who were seen for assessment in the chest pain clinic. A retrospective design was chosen as it allowed historical data to be collected which could then be used to evaluate current practice, while the audit provided information on practice standards and insight into areas for quality health service improvement.
METHODOLOGY
The study was conducted on 743 consecutive patients between the ages of 35 to 85 years of age who were assessed in the chest pain clinic from 1 July 2011 to 28 February 2014. Of those, 214 were excluded as they had known disease or had been assessed for reasons other than coronary artery disease. A total of 529 eligible patients with mild, moderate or high cardiovascular risk scores and typical or atypical symptoms were included in the final analysis. The audit was completed using information from the chest pain clinic database which captures anonymous information on all patients who are seen in the chest pain clinic and records gender, cardiovascular risk, typical or atypical symptoms and outcomes of exercise treadmill test and further tests. Re-admission rates at six months were obtained using the electronic patient record system that captures all admissions to the hospital and emergency department. Major adverse cardiac events (myocardial infarction, unstable angina, and cardiac death) and any admission to the emergency department were recorded six months after exercise testing for all patients. Descriptive and inferential statistics were used to describe data and examine relationships between the different cardiovascular risk groups. Ethical approval was obtained from the Research Ethics *and Approvals Committee of the Eastern Institute of Technology and locality approval was obtained from the local District Health Board where the research took place.
RESULTS
Of the five hundred and twenty-nine patients included in the audit, 207 had mild cardiovascular risk, 164 had moderate cardiovascular risk and 158 had high cardiovascular risk. There was a predominance of atypical symptoms in all three risk groups: mild 82%; moderate 70%; and high 62%. Positive exercise treadmill outcomes were lower in those with mild and moderate cardiovascular risk (21% and 33%) while the greatest percentage was seen in those with high cardiovascular risk (42%). Positive exercise treadmill results were generally referred for coronary angiography regardless of cardiovascular risk with a small number being discharged for general practitioner follow up, review with a cardiologist, or stress echocardiography. Coronary angiography following a positive exercise treadmill test confirmed disease in 31% of patients with mild cardiovascular risk, 81% with moderate cardiovascular risk and 80% with high cardiovascular risk. The false positive rate was greatest in those with mild risk (68%), compared to 19% and 25% in the moderate and high risk groups. In patients with atypical symptoms, disease was confirmed in 5% of patients with mild cardiovascular risk, 25% with moderate cardiovascular risk and 27% with high cardiovascular risk. By contrast, typical symptoms and a positive exercise treadmill test confirmed disease in 8% with mild cardiovascular risk, 28% with moderate cardiovascular risk and 40% with high cardiovascular risk. Of 529 patients there were 34 (6%) re-presentations to the emergency department within six months. Eleven presented with cardiac chest pain, all were waiting for angiography or stress echo which was expedited, and six were confirmed to have disease.
CONCLUSION
These findings suggest that due to the low diagnostic result of coronary artery disease in the person with mild cardiovascular risk and atypical symptoms, the exercise treadmill test is not efficacious, raising the question whether it is an appropriate use of the resource in this cohort or whether alternative management strategies need to be considered. Education by primary care health professionals on lifestyle and cardiovascular risk has the potential to improve health outcomes for at risk patients and reduce cardiovascular risk over time. Currently, New Zealand's public health care system is faced with fiscal and resource constraints related to the high costs associated with health care delivery and the challenge exists for district health boards to address these constraints and make service delivery as efficient as possible. While exercise treadmill test results were less accurate in those with mild cardiovascular risk and atypical symptoms this was not the case in those with typical symptoms, confirming its value in this cohort. While this research provides important information on the chest pain clinic service it is essential to acknowledge the limitations of this study when interpreting the results. A retrospective methodology has inherent weaknesses related to selection bias which are unavoidable due to the historic nature of this design. Other factors that threaten reliability and validity need to be considered such as data entry errors and misinterpretation of test results. This research occurred at a single centre and is therefore not generalisable to other populations. Further research in a similar non-acute, outpatient population in New Zealand would be beneficial and a prospective study would provide additional methodological rigor.
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