Smaller LDL particles are more problematic (LDL cholesterol particle number higher) More able to penetrate the endothelium (lining of blood vessels) and cause damage, where eventually plaque builds up o Total measurement of LDL is not as indicative as knowing the distribution between small and large particles o Can use nuclear magnetic resonance spectrometers which are capable of measuring LDL particle size o Instrumentation is available, but not cheap o Atheroscleroic culprit is not LDL cholesterol or number of LDL particles, but size Eventually we will be getting lipoprofiles indicating LDL particle size as a best predictor for heart disease
Once there is already plaque inside coronary arteries, the question is whether a blood clot will form around plaque or not and cause a heart attack o Occurs when plaque bursts open leading to body perceiving it as a site of damage o Many blood cells will arrive to curb the damage and form a blood clot o BUT can block flow of blood can cause heart attack o Whether plaque will burst or not depends on inflammation Inflammation is a response of body tissues to injury or irritation; characterized by pain, swelling, redness, and heat When inflammation occurs in the arteries it makes plaque more susceptible to breaking A measure can be taken called high-sensitivity C-reactive protein that, when levels are less than 2mg/L, risk of heart disease decreases Lesson 3: Diet and the Heart II Video 1 Intervention studies – intervene in one group and not with another, see the difference in results First important intervention study done for cholesterol and heart disease was MRFIT – multiple risk factor intervention trial o After 7 years intervention group reduced saturated fat intake by 30% and increased polyunsaturated fats by 33% Saturated fat was believed the be the villain in heart disease based on Keys’ study and others o Difference between intervention and control group in blood cholesterol was 2% Control group reduced by 5% probably due to being influenced by the study and eating better o Mortality rate in intervention group from coronary heart disease was 17.9 per 1000 and in control group 19.3 per 1000 Might have been more substantial if difference in blood cholesterol was larger o Study involved many authors, most in connection to pharmaceutical companies o Overall, MRFIT showed that intervening in many kinds of ways can reduce risk of heart disease, but not very significantly 1984: Lipid research clinics coronary primary prevention trial CPPT o 3,806 high risk men ages 35-59 o Half treated with diet cut down on saturated fats, increase polyunsaturated o Other half treated with diet plus drug cholestyramine to further lower blood cholesterol o Blood cholesterol decreased by 9% in intervention group and decrease in heart attacks by 19% o For every 1% decrease in cholesterol, the risk of heart attack is decreased by 2% Means you would need to treat 67 men quite aggressively with diet and drug to save one cardiac event
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