ATHEROSCLEROSIS UPDATE ATHEROSCLEROSE: LE POINT Canadian Atherosclerosis Society / Societe canadienne d'atherosclerose
Obesity and coronary heart disease Daniel A.K. Roncari, MD, PhD, FRCPC, FACP T he purported correlation between obesity and coronary heart disease is complex, but it may not even pertain to certain types of obesity.' A strong correlation exists between abdominal obesity (as demonstrated by an increased waisthip circumference ratio) and the following atherogenic risk factors: hypertension, a low plasma level of high-density lipoprotein cholesterol (HDL-C), hyperinsulinemia, impaired glucose tolerance (or frank type II diabetes) and atherosclerotic complications, particularly coronary heart disease.' More specifically, the strongest association is between the mass of intra-abdominal (visceral) fat and these risk factors or any eventual complication.' After accounting for abdominal fat accumulation there is little, if any, remaining correlation between the degree of total body adiposity, or of body mass index, and atherogenic factors.' Such virtual lack of correlation fits with the following fact, which is generally not appreciated: several people with massive obesity (body mass index above 45 kg/M2), although burdened with numerous problems, do not have premature coronary heart disease. In contrast to the moderate degree of adiposity usually present in people with adult-onset abdominal obesity, those with massive obesity usually have diffuse fat distribution (with possible gynecoid or gluteal-femoral accentuation) and childhood-onset obesity.' Two large prospective studies have examined the influence of obesity on cardiovascular problems, notably coronary heart disease.2'3 After accounting for some atherogenic risk factors obesity appeared to confer an "independent" risk, which was more evident in men than in women.23 However, neither
study accounted for the subjects' HDL-C levels, which have a strong inverse correlation with the risk of coronary heart disease. Other factors, such as the concentration and size of lipoprotein (a), should also be considered in future studies. Thus, it is not at all certain whether obesity is an independent risk factor. Moreover, in the two studies a distinction between abdominal obesity and gynecoid or diffuse childhood-onset obesity (although only a small number had massive obesity) would probably have revealed that only the android form was significantly associated with an increased risk of coronary heart disease. The two studies also indicated that weight gain after 18 years of age was important in terms of an increased risk of coronary heart disease.23 The risk of coronary heart disease is much higher in obese men who were lean as infants than in those who were plump.4 In conclusion, coronary heart disease is particularly related to abdominal obesity.
References 1. Bouchard C, Bray GA, Hubbard VS: Basic and clinical aspects of regional fat distribution. Am J Clin Nutr 1990; 52: 946-950 2. Hubert HB, Feinleib M, McNamara PM et al: Obesity as an independent risk factor for cardiovascular disease: a 26-year follow-up of participants in the Framingham Heart Study. Circulation 1983; 83: 968-977 3. Manson JE, Colditz GA, Stampfer MJ et al: A prospective study of obesity and risk of coronary heart disease in women. N Engl J Med 1990; 322: 882-889 4. Barker DJP, Winter PD, Osmond C et al: Weight in infancy and death from ischaemic heart disease. Lancet 1989; 2: 577580
Dr. Roncari is professor ofmedicine at the University of Toronto and physician-in-chief at Sunnybrook Health Science Centre, Toronto, Ont. He is also president ofthe Canadian Atherosclerosis Society.
The opinions expressed in this article are those of the author and not necessarily those of the Canadian Atherosclerosis Society. Reprint requests to: Dr. Daniel A.K Roncari, Physician-in-chief; Sunnybrook Health Science Centre, 2075 Bayview Ave., Toronto, ON M4N 3M5 FEBRUARY 15, 1992
CAN MED ASSOC J 1992; 146 (4)
525
Obesity and coronary heart disease Daniel A.K. Roncari, MD, PhD, FRCPC, FACP T he purported correlation between obesity and coronary heart disease is complex, but it may not even pertain to certain types of obesity.' A strong correlation exists between abdominal obesity (as demonstrated by an increased waisthip circumference ratio) and the following atherogenic risk factors: hypertension, a low plasma level of high-density lipoprotein cholesterol (HDL-C), hyperinsulinemia, impaired glucose tolerance (or frank type II diabetes) and atherosclerotic complications, particularly coronary heart disease.' More specifically, the strongest association is between the mass of intra-abdominal (visceral) fat and these risk factors or any eventual complication.' After accounting for abdominal fat accumulation there is little, if any, remaining correlation between the degree of total body adiposity, or of body mass index, and atherogenic factors.' Such virtual lack of correlation fits with the following fact, which is generally not appreciated: several people with massive obesity (body mass index above 45 kg/M2), although burdened with numerous problems, do not have premature coronary heart disease. In contrast to the moderate degree of adiposity usually present in people with adult-onset abdominal obesity, those with massive obesity usually have diffuse fat distribution (with possible gynecoid or gluteal-femoral accentuation) and childhood-onset obesity.' Two large prospective studies have examined the influence of obesity on cardiovascular problems, notably coronary heart disease.2'3 After accounting for some atherogenic risk factors obesity appeared to confer an "independent" risk, which was more evident in men than in women.23 However, neither
study accounted for the subjects' HDL-C levels, which have a strong inverse correlation with the risk of coronary heart disease. Other factors, such as the concentration and size of lipoprotein (a), should also be considered in future studies. Thus, it is not at all certain whether obesity is an independent risk factor. Moreover, in the two studies a distinction between abdominal obesity and gynecoid or diffuse childhood-onset obesity (although only a small number had massive obesity) would probably have revealed that only the android form was significantly associated with an increased risk of coronary heart disease. The two studies also indicated that weight gain after 18 years of age was important in terms of an increased risk of coronary heart disease.23 The risk of coronary heart disease is much higher in obese men who were lean as infants than in those who were plump.4 In conclusion, coronary heart disease is particularly related to abdominal obesity.
References 1. Bouchard C, Bray GA, Hubbard VS: Basic and clinical aspects of regional fat distribution. Am J Clin Nutr 1990; 52: 946-950 2. Hubert HB, Feinleib M, McNamara PM et al: Obesity as an independent risk factor for cardiovascular disease: a 26-year follow-up of participants in the Framingham Heart Study. Circulation 1983; 83: 968-977 3. Manson JE, Colditz GA, Stampfer MJ et al: A prospective study of obesity and risk of coronary heart disease in women. N Engl J Med 1990; 322: 882-889 4. Barker DJP, Winter PD, Osmond C et al: Weight in infancy and death from ischaemic heart disease. Lancet 1989; 2: 577580
Dr. Roncari is professor ofmedicine at the University of Toronto and physician-in-chief at Sunnybrook Health Science Centre, Toronto, Ont. He is also president ofthe Canadian Atherosclerosis Society.
The opinions expressed in this article are those of the author and not necessarily those of the Canadian Atherosclerosis Society. Reprint requests to: Dr. Daniel A.K Roncari, Physician-in-chief; Sunnybrook Health Science Centre, 2075 Bayview Ave., Toronto, ON M4N 3M5 FEBRUARY 15, 1992
CAN MED ASSOC J 1992; 146 (4)
525
