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Cardiovascular Diseases – Focus on Hypertension
Published by: By Pfizer Staff
Date of publishing: 20th Nov 2017
Cardiovascular disease (CVD) is the leading cause of death worldwide, accounting for approximately 30% of all deaths.1 Hypertension is probably the most important modifiable risk factor for CVD. It is defined as a systolic blood pressure (SBP) ≥140 mm Hg and/or diastolic blood pressure (DBP) ≥90 mm Hg.2 Elevated blood pressure (BP) is an important public health concern. It is highly prevalent and leads to several adverse cardiovascular outcomes, especially coronary heart disease (CHD), stroke, and heart failure (HF).2
The renin-angiotensin system3 may be the most important of the endocrine systems that affect the control of blood pressure. Renin is secreted from the juxtaglomerular apparatus of the kidney in response to glomerular underperfusion or a reduced salt intake. It is also released in response to stimulation from the sympathetic nervous system.
Renin is responsible for converting renin substrate (angiotensinogen) to angiotensin I, a physiologically inactive substance which is rapidly converted to angiotensin II in the lungs by angiotensin converting enzyme (ACE). Angiotensin II is a potent vasoconstrictor and thus causes a rise in blood pressure. In addition it stimulates the release of aldosterone from the zona glomerulosa of the adrenal gland, which results in a further rise in blood pressure related to sodium and water retention.3
Figure 2. Target organ effects of angiotensin II. GFR=glomerular filtration rate; HF=heart failure; MI=myocardial infarction.
Management of Hypertension
The European Society of Cardiology (ESC) guidelines4 for the management of arterial hypertension (2013) recommend assessment of the condition should include cardiovascular risk stratification, blood pressure measurements, lifestyle changes and physical examination.4
Table 1: Classification of blood pressure levels. Values are presented in mm Hg. DBP=diastolic blood pressure; SBP= systolic blood pressure. Adapted from Mancia G, J Hypertens. 2013;31(7): 1281-1357 4
There is a large body of evidence documenting the beneficial effects of antihypertensive therapy in the prevention of morbidity and mortality related to CVD.
The Blood Pressure Lowering Treatment Trialists’ Collaboration5 conducted a large meta-analysis of 11 trials and 26 randomised groups met the inclusion criteria, and included 67 475 individuals, of whom 51 917 had available data for the calculation of cardiovascular risk. Four thousand one hundred and sixty-seven (8%) had a cardiovascular event during a median of 4·0 years (IQR 3·4–4·4) of follow-up. The mean estimated baseline levels of 5-year cardiovascular risk for each of the four risk groups were 6·0% (SD 2·0), 12·1% (1·5), 17·7% (1·7), and 26·8% (5·4). In each consecutive higher risk group, blood pressure-lowering treatment reduced the risk of cardiovascular events relatively by 18% (95% CI 7–27), 15% (4–25), 13% (2–22), and 15% (5–24), respectively (p=0·30 for trend). The study showed that in absolute terms, treating 1000 patients in each group with blood pressure-lowering treatment for 5 years would prevent 14 (95% CI 8–21), 20 (8–31), 24 (8–40), and 38 (16–61) cardiovascular events, respectively (p=0·04 for trend). The study conclusions were that lowering blood pressure provides similar relative protection at all levels of baseline cardiovascular risk, but progressively greater absolute risk reductions as baseline risk increases. These results support the use of predicted baseline cardiovascular disease risk equations to inform blood pressure-lowering treatment decisions.5
WHO, Cardiovascular Diseases, updated May 2017, accessed from: http://www.who.int/mediacentre/factsheets/fs317/en/ on 19/10/17
Rogriguez, C.J et al, JAMA Intern Med. 2014 Aug; 174(8): 1252–1261. Accessed from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4573449/ on 19/10/1
Foex P et al, Continuing Education in Anaesthesia Critical Care & Pain, Volume 4, Issue 3, 1 June 2004, Pages 71–75, Accessed from: https://academic.oup.com/bjaed/article/4/3/71/292146/Hypertension-pathophysiology-and-treatment on 19/10/17
Mancia G, J Hypertens. 2013;31(7): 1281-1357, European Society of Cardiology, (ESC) Practise Guidelines, Management of Arterial Hypertension, accessed from: https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Arterial-Hypertension-Management-of on 19/10/17
The Blood Pressure Lowering Treatment Trialists' Collaboration, Blood pressure-lowering treatment based on cardiovascular risk: a meta-analysis of individual patient data, The Lancet, Volume 384,No.9943, p591-598,16 August 2014 accessed from: http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(14)61212-5/abstract on 19/10/17