Coronary heart disease: Difference between revisions

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Revision as of 09:57, 24 July 2007

Coronary heart disease is caused by abnormalities the arteries that suppy the heart with blood. Those arteries are called the coronary arteries and the usual cause of coronary artery disease is athersosclerosis. Atherosclerosis is a degenerative disease of the arterial walls, in which the normal elastic walls of the arteries become thickened and replaced with deposits of fatty material, including cholesterol. As the walls of the affected arteries thicken, the hollow lumen at the center of each, that conduit through which oxygen enriched blood normally pulses, becomes narrower and, eventually, the flow of blood within it is decreased. With narrowing of the artery's lumen and reduced flow comes the risk of sudden occlusion of the artery, especially if the lining is abnormally roughened by deposits of irregular plaques of minerals and fats.


Prevention

Coronary heart disease is the most common form of heart disease in the Western world. Prevention centers on the modifiable risk factors, which include decreasing cholesterol levels, addressing obesity and hypertension, avoiding a sedentary lifestyle, making healthy dietary choices, and stopping smoking. There is some evidence that lowering uric acid and homocysteine levels may contribute. In diabetes mellitus, there is little evidence that blood sugar control actually improves cardiac risk. Some recommend a diet rich in omega-3 fatty acids and vitamin C. The World Health Organization (WHO) recommends "low to moderate alcohol intake" to reduce risk of coronary heart disease.[1]

An increasingly growing number of other physiological markers and homeostatic mechanisms are currently under scientific investigation. Among these markers are low density lipoprotein and asymmetric dimethylarginine. Patients with CHD and those trying to prevent CHD are advised to avoid fats that are readily oxidized (e.g., saturated fats and trans-fats), limit carbohydrates and processed sugars to reduce production of Low density lipoproteins while increasing High density lipoproteins, keeping blood pressure normal, exercise and stop smoking. These measures limit the progression of the disease. Recent studies have shown that dramatic reduction in LDL levels can cause mild regression of coronary heart disease.

Exercise

Separate to the question of the benefits of exercise; it is unclear whether doctors should spend time counseling patients to exercise. The U.S. Preventive Services Task Force (USPSTF), based on a systematic review of randomized controlled trials, found 'insufficient evidence' to recommend that doctors counsel patients on exercise.[2] However, the American Heart Association, based on a non-systematic review, recommends that doctors counsel patients on exercise [3]

Preventive diets

Dietary changes can potentially lead to large changes in the cholesterol.[4]

Aspirin

Aspirin, in doses of less than 75 to 81 mg/d[5], can reduce the incidence of cardiovascular events.[6] The U.S. Preventive Services Task Force 'strongly recommends that clinicians discuss aspirin chemoprevention with adults who are at increased risk for coronary heart disease'.[7] The Task Force defines increased risk as 'Men older than 40 years of age, postmenopausal women, and younger persons with risk factors for coronary heart disease (for example, hypertension, diabetes, or smoking) are at increased risk for heart disease and may wish to consider aspirin therapy'. More specifically, high-risk persons are 'those with a 5-year risk ≥ 3%'. A risk calculator is available.[8]

Regarding healthy women, the more recent Women's Health Study randomized controlled trial found insignficant benefit from aspirin in the reduction of cardiac events; however there was a signficant reduction in stroke.[9] Subgroup analysis showed that all benefit was confined to women over 65 years old.[9] In spite of the insignficant benefit for women < 65 years old, recent practice guidelines by the American Heart Association recommend to 'consider' aspirin in 'healthy women' <65 years of age 'when benefit for ischemic stroke prevention is likely to outweigh adverse effects of therapy'.[10]

Omega-3 fatty acids (fish oil)

The benefit of fish oil is controversial with conflicting conclusions reached by a negative meta-analysis[11] of randomized controlled trials by the international Cochrane Collaboration and a partially positive systematic review[12] by the Agency for Healthcare Research and Quality.

References

  1. ↑ http://www.who.int/nutrition/topics/5_population_nutrient/en/index12.html
  2. ↑ (2002) "Behavioral counseling in primary care to promote physical activity: recommendation and rationale". Ann. Intern. Med. 137 (3): 205-7. PMID 12160370. [e]
  3. ↑ Thompson PD, Buchner D, Pina IL, et al (2003). "Exercise and physical activity in the prevention and treatment of atherosclerotic cardiovascular disease: a statement from the Council on Clinical Cardiology (Subcommittee on Exercise, Rehabilitation, and Prevention) and the Council on Nutrition, Physical Activity, and Metabolism (Subcommittee on Physical Activity)". Circulation 107 (24): 3109-16. DOI:10.1161/01.CIR.0000075572.40158.77. PMID 12821592. Research Blogging. http://www.ngc.gov/summary/summary.aspx?ss=15&doc_id=5360&string=#s23
  4. ↑ McMurry MP, Cerqueira MT, Connor SL, Connor WE (1991). "Changes in lipid and lipoprotein levels and body weight in Tarahumara Indians after consumption of an affluent diet". N. Engl. J. Med. 325 (24): 1704-8. PMID 1944471. [e]
  5. ↑ Campbell CL, Smyth S, Montalescot G, Steinhubl SR (2007). "Aspirin dose for the prevention of cardiovascular disease: a systematic review". JAMA 297 (18): 2018-24. DOI:10.1001/jama.297.18.2018. PMID 17488967. Research Blogging.
  6. ↑ Berger J, Roncaglioni M, Avanzini F, Pangrazzi I, Tognoni G, Brown D (2006). "Aspirin for the primary prevention of cardiovascular events in women and men: a sex-specific meta-analysis of randomized controlled trials". JAMA 295 (3): 306-13. PMID 16418466.
  7. ↑ (2002) "Aspirin for the primary prevention of cardiovascular events: recommendation and rationale". Ann Intern Med 136 (2): 157-60. PMID 11790071.
  8. ↑ http://www.med-decisions.com/
  9. ↑ 9.0 9.1 Ridker P, Cook N, Lee I, Gordon D, Gaziano J, Manson J, Hennekens C, Buring J (2005). "A randomized trial of low-dose aspirin in the primary prevention of cardiovascular disease in women". N Engl J Med 352 (13): 1293-304. DOI:10.1056/NEJMoa050613. PMID 15753114. Research Blogging.
  10. ↑ http://circ.ahajournals.org/cgi/content/abstract/CIRCULATIONAHA.107.181546v1
  11. ↑ Hooper L, Thompson RL, Harrison RA, Summerbell CD, Ness AR, Moore HJ, Worthington HV, Durrington PN, Higgins JP, Capps NE, Riemersma RA, Ebrahim SB, Davey Smith G (2006). "Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: systematic review". BMJ 332 (7544): 752-60. DOI:10.1136/bmj.38755.366331.2F. PMID 16565093. Research Blogging.
  12. ↑ Wang C, Harris WS, Chung M, Lichtenstein AH, Balk EM, Kupelnick B, Jordan HS, Lau J (2006). "n-3 Fatty acids from fish or fish-oil supplements, but not alpha-linolenic acid, benefit cardiovascular disease outcomes in primary- and secondary-prevention studies: a systematic review". Am. J. Clin. Nutr. 84 (1): 5-17. PMID 16825676. [e] http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=hstat1a.chapter.38290
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