Background Information

  • What is coronary heart disease?

The coronary arteries are the blood vessels responsible for supplying the heart with oxygenated blood. In patients who suffer from coronary heart disease (CHD), the walls of these blood vessels become built up with a fatty material called atheroma, thus causing a narrowing of the arteries and therefore a reduced blood flow. This build-up of atheroma is called atherosclerosis. The atherosclerosis will cause patients to suffer from symptoms of pain and discomfort known as angina. In some cases, pieces of the atheroma will break off and consequently block the coronary artery and all blood flow into the heart will stop. The heart will never fully recover from this and will remain permanently damaged. This is known as a heart attack. (Bhf.org.uk, 2019)

 

  • Risks

Smoking greatly increases the risk of an individual developing CHD, with smokers being 24% more likely to develop the disease when compared with non-smokers (nhs.uk, 2019). A meta-analysis study was conducted by (He et al., 1999) which looked into the relationship between passive smoking and the risk of developing CHD. The study used cohort studies to conclude that there is a small increase in the risk of developing CHD. Further research suggests this is due to the nicotine and carbon monoxide compounds present in the cigarettes, which put strain on the heart by causing it to work harder to maintain a constant oxygen supply around the body (nhs.uk, 2019). Despite being able to directly calculate cumulative incidences of the disease using the cohort studies, a criticism of using them is that they require the research carried out to be longitudinal to fully comprehend whether or not the smoking had any effect on developing CHD and participants would have to be examined at regular intervals for the rest of their lives for this study and its results to be considered reliable.

 

Age is also considered a risk for developing the disease and some studies have shown that CHD is more prevalent in individuals over the age of 40. With 1 in 2 men and 1 in 4 women over this age developing CHD. However, as age increases further the risk for developing CHD decreases to 1 in 3 for men but remains the same for women. Thus, suggesting the most vulnerable group is men between the ages of 40 and 70 (Lloyd-Jones and Levy, 1999). This was a longitudinal study and a benefit from conducting such a study is that it is very effective in determining patterns in the data over time, which therefore increases the validity of the research conducted. A criticism of using this type of study would be that patients weren’t all examined the same amount of times with the study simply referring to each patient being examined ‘at least once’. This shows that standardised procedure was not carried out throughout the duration of the study, consequently leading us to doubt the reliability of the study.

 

  • Prevention

Despite popular belief, alcohol intake (to an extent) has been found to decrease an individual’s risk of developing CHD. In a 1999 meta-analysis study conducted by (B Rimm, 1999) was used to ascertain if there was a correlation between moderate alcohol intake and a lowered risk of developing CHD. The study used biological markers such as concentrations of high-density lipoproteins and apoliprotein A I to detect whether an individual was more or less at developing the disease after consuming up to 30 grams of alcohol per day. The study used 61 data records, abstracted from 42 eligible studies which concluded that there is a casual relationship between alcohol intake and lowered risk of coronary heart disease. Despite these positive results, meta- analysis studies lack reliability because each study may have been conducted slightly differently and used a different methodology to one another or maybe a different brand of alcohol. Thus meaning, the results from this study cannot be generalised to the general public due to its lack of control and reliability throughout when all individual studies are compared.

 

Exercise is considered an excellent prevention method for CHD. It has been found to have been an association between exercise (brisk walking and vigorous exercise) and reductions in incidence of coronary events among women. This inverse association between the 2 show that women in the walking group, who walked 3 or more hours per week at a brisk pace, had a multivariate relative risk when compared with women who walked infrequently (Manson et al., 1999). Therefore, showing that exercise is an effective way at preventing coronary heart disease. However, due to the gender specific nature of this study, these findings cannot be generalised to men because women were the only participants and there is therefore a low validity for this study. To improve, the study should aim to be gender representative of the population it wishes to generalise the results to.

 

  • Exercise as a treatment for coronary heart disease

The risk of developing CHD is greatly increased if the individual is considered to be obese and or overweight (nhs.uk, 2019). Due to this, exercise is seen as an excellent treatment for the disease, with some studies even claiming exercise based cardiac rehabilitation is effective in reducing total cardiovascular mortality (in medium to long term studies, i.e. 12 or more months follow up) and hospital admissions in short term studies (shorter than 12 months) (S Heran et al., 2011). However, a huge limitation to this study is that the majority of its participants were male, middle aged and considered a low risk of developing CHD. This poses as a limitation because it does not represent the general population and thus means the conclusions drawn from this study cannot be generalised to the general public due to its lack of validity.

 

  • References:

B Rimm, E. (1999). Moderate alcohol intake and lower risk of coronary heart disease; meta analysis of effects of lipids and haemostat factors. The BMJ, [online] 319(1523). Available at: https://www.bmj.com/content/319/7224/1523.short?casa_token=AcIpWbkqwVsAAAAA:F4YOOIXnLCHdWY7d8FxTXUgP4Flah2zaEglCZBPmKqZau4efYjXlJWO86G3y2dy5l7iA_ITxQ2tW [Accessed 13 Dec. 2019].

 

Bhf.org.uk. (2019). Coronary heart disease (CHD). [online] Available at: https://www.bhf.org.uk/informationsupport/conditions/coronary-heart-disease [Accessed 13 Dec. 2019].

 

nhs.uk. (2019). Coronary heart disease – Causes. [online] Available at: https://www.nhs.uk/conditions/coronary-heart-disease/causes/ [Accessed 13 Dec. 2019].

 

He, J., Vupputuri, S., Allen, K., Prerost, M., Hughes, J. and Whelton, P. (1999). Passive Smoking and the Risk of Coronary Heart Disease — A Meta-Analysis of Epidemiologic Studies. New England Journal of Medicine, [online] 340(12), pp.920-926. Available at: https://www.nejm.org/doi/full/10.1056/NEJM199903253401204 [Accessed 13 Dec. 2019].

 

Manson, J., Hu, F., Rich-Edwards, J., Colditz, G., Stampfer, M., Willett, W., Speizer, F. and Hennekens, C. (1999). A Prospective Study of Walking as Compared with Vigorous Exercise in the Prevention of Coronary Heart Disease in Women. New England Journal of Medicine, [online] 341(9), pp.650-658. Available at: https://www.nejm.org/doi/full/10.1056/NEJM199908263410904 [Accessed 13 Dec. 2019].

 

S Heran, B., NH Chen, J., Ebrahim, S., Moxham, T., Oldridge, N., Rees, K., R Thompson, D. and S Taylor, R. (2011). Exercise- based cardiac rehabilitation for coronary heart disease. Cochrane Library. [online] Available at: https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD001800.pub2/abstract [Accessed 13 Dec. 2019].

 

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