Philip Greenland

American College of Cardiology/American Heart Association expert consensus document on electron-beam computed tomography for the diagnosis and prognosis of coronary artery disease

Coronary artery calcification is part of the development of atherosclerosis; it occurs exclusively in atherosclerotic arteries and is absent in the normal vessel wall. Electron-beam computed tomography (EBCT), the focus of this document, is a highly sensitive technique for detecting coronary artery calcium and is being used with increasing frequency for the screening of asymptomatic people to assess those at high risk for developing coronary heart disease (CHD) and cardiac events, as well as for the diagnosis of obstructive coronary artery disease (CAD) in symptomatic patients. The use of EBCT has the greatest potential for further determination of risk, particularly in elderly asymptomatic patients and others at intermediate risk. The calcium score has been advocated by some as a potential surrogate for age in risk-assessment models. EBCT has also been proposed as a useful technique for assessing the progression or regression of coronary artery stenosis in response to treatment of risk factors such as hypercholesterolemia.nnEBCT uses an electron beam in stationary tungsten targets, which permits very rapid scanning times. Serial transaxial images are obtained in 100 ms with a thickness of 3 to 6 mm for purposes of detecting coronary artery calcium. Thirty to 40 adjacent axial scans are obtained during 1 to 2 breath-holding sequences. Current EBCT software permits quantification of calcium area and density. Histological studies support the association of tissue densities of 130 Hounsfield units (HU) with calcified plaque. However, a plaque vulnerable to fissure or erosion can be present in the absence of calcium. Also, sex differences play a role in the development of coronary calcium, the prevalence of calcium in women being half that of men until age 60 years. EBCT calcium scores have correlated with pathological examination of the atherosclerotic plaque.nnThis American College of Cardiology (ACC)/American Heart Association (AHA) Writing Group reviewed …

Primary Prevention of Coronary Heart Disease: Guidance From Framingham A Statement for Healthcare Professionals From the AHA Task Force on Risk Reduction

The Framingham Heart Study has contributed importantly to understanding of the causes of coronary heart disease (CHD), stroke, and other cardiovascular diseases. Framingham research has helped define the quantitative and additive nature of these causes or, as they are now called, “cardiovascular risk factors.”1 The National Cholesterol Education Program (NCEP)2 3 has made extensive use of Framingham data in developing its strategy for preventing CHD by controlling high cholesterol levels. The NCEP guidelines2 3 adjust the intensity of cholesterol-lowering therapy with absolute risk as determined by summation of risk factors. The National High Blood Pressure Education Program (NHBPEP) has set forth a parallel approach for blood pressure control. In contrast to the NCEP,2 however, earlier NHBPEP reports issued through the Joint National Committee4 did not match the intensity of therapy to absolute risk for CHD. “Normalization” of blood pressure is the essential goal of therapy regardless of risk status. Blood pressure–lowering therapy is carried out as much for prevention of stroke and other cardiovascular complications as for reduction of CHD risk. Nonetheless, risk assessment could be important for making decisions about type and intensity of therapy for hypertension. Thus, the most recent Joint National Committee report5 gives more attention to risk stratification for adjustment of therapy for hypertension. Although Framingham data have already been influential in the development of national guidelines for risk factor management, the opportunity may exist for both cholesterol and blood pressure programs to draw more extensively from Framingham results when formulating improved risk assessment guidelines and recommending more specific strategies for risk factor modification.nnThe American Heart Association has previously used Framingham risk factor data to prepare charts for estimating CHD risk. Framingham investigators of the National Heart, Lung, and Blood Institute prepared the original charts and have now revised …