Coronary Artery Calcium Scanning in Asymptomatic Patients with Diabetes Mellitus: A Paradigm Shift.
ABSTRACT Coronary artery calcium (CAC) is the most powerful cardiac risk prognosticator in the asymptomatic population, with consistent superiority to all risk factor based paradigms. More recently, the strong prognostic value of changes in CAC has been demonstrated. The application of CAC to asymptomatic patients with diabetes mellitus (DM), all of whom have been presumed to be of high risk, has yielded a range of risks from low to high, proportional to the amount of calcified plaque as in patients without DM. These risks are higher than in nondiabetic patients at corresponding CAC levels, except for those without CAC who have the same low risk as nondiabetic patients. In addition, the value of serial scanning to assess plaque progression and prognosis in persons with DM has been demonstrated. Therefore, we propose that : 1) DM is not a coronary artery disease equivalent; 2) CAC be routinely employed in all asymptomatic diabetic patients older than 40 years as proposed by ACC/AHA guidelines; 3) serial CAC scanning be considered for evaluation of the response to therapy.
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ABSTRACT: The South Bay Heart Watch is a prospective cohort study designed to appraise the value of coronary calcium and risk factors for predicting outcomes in asymptomatic adults. Two factors that may be related to subsequent cardiovascular events are coronary calcium (CAC, a manifestation of subclinical atherosclerosis) and high-sensitivity C-reactive protein (CRP, a measure of chronic inflammation). Between December 1990 and December 1992, 1461 participants without coronary heart disease underwent baseline risk factor screening, computed tomography for CAC, and measurement of CRP. Participants were followed up for 6.4+/-1.3 years. Cox regression analyses were conducted for the 967 nondiabetics with CRP levels < or =10 mg/L to estimate the risk-factor-adjusted relative risks of CAC and CRP for the occurrence of (1) nonfatal myocardial infarction (MI) or coronary death and (2) any cardiovascular event (MI, coronary death, coronary revascularization, or stroke). CAC was a predictor of both end points (P<0.005), and CRP was a predictor of any cardiovascular event (P=0.03). Risk group analysis defined by tertiles for CAC (<3.7, 3.7 to 142.1, >142.1) and the 75th percentile for CRP (>4.05 mg/L) indicated that there was increasing risk with increasing calcium and CRP. Relative risks for the medium-calcium/low-CRP risk group to high-calcium/high-CRP risk group ranged from 1.8 to 6.1 for MI/coronary death (P=0.003) and 2.8 to 7.5 for any cardiovascular event (P<0.001). Participants without diabetes and those at intermediate risk may benefit from risk stratification based on high-sensitivity CRP levels and CAC, because both factors contribute independently toward the incidence of cardiovascular events.Circulation 10/2002; 106(16):2073-7. · 15.20 Impact Factor
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ABSTRACT: There is a clear relationship between absolute calcium scores (CS) and severity of coronary artery disease. However, hard coronary events have been shown to occur across all ranges of CS. We conducted 2 analyses: in group A, 172 patients underwent electron-beam CT (EBCT) imaging within 60 days of suffering an unheralded myocardial infarction. In group B, 632 patients screened by EBCT were followed up for a mean of 32+/-7 months for the development of acute myocardial infarction or cardiac death. The mean patient age and prevalence of coronary calcification were similar in the 2 groups (53+/-8 versus 52+/-9 years and 96% each). In group B, the annualized event rate was 0.11% for subjects with CS of 0, 2.1% for CS 1 to 99, 4.1% for CS 100 to 400, and 4.8% for CS >400, and only 7% of the patients had CS >400. However, mild, moderate, and extensive absolute CSs were distributed similarly between patients with events in both groups (34%, 35%, and 27%, respectively, in group A and 44%, 30%, and 22% in group B). In contrast, the majority of events in both groups occurred in patients with CS >75th percentile (70% in each group). Coronary calcium is present in most patients who suffer acute coronary events. Although the event rate is greater for patients with high absolute CSs, few patients have this degree of calcification on a screening EBCT. Conversely, the majority of events occur in individuals with high CS percentiles. Hence, CS percentiles constitute a more effective screening method to stratify individuals at risk.Circulation 02/2000; 101(8):850-5. · 15.20 Impact Factor
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ABSTRACT: The purpose of this study was to determine the prognostic accuracy of electron beam computed tomographic (CT) scanning of the coronary arteries and the relationship of coronary calcification to standard coronary disease risk factors and C-reactive protein (CRP) in the prediction of atherosclerotic cardiovascular disease (ASCVD) events in apparently healthy middle-age persons. As a screening test for coronary artery disease (CAD), electron beam CT scanning remains controversial. In a prospective, population-based study, 4,903 asymptomatic persons age 50 to 70 years underwent electron beam CT scanning of the coronary arteries. At 4.3 years, follow-up was available in 4,613 participants (94%), and 119 had sustained at least one ASCVD event. Subjects with ASCVD events had higher baseline coronary calcium scores (median [interquartile range], Agatston method) than those without events: 384 (127, 800) versus 10 (0, 86) (p < 0.0001). For coronary calcium score threshold > or = 100 versus < 100, relative risk (95% confidence interval) was 9.6 (6.7 to 13.9) for all ASCVD events, 11.1 (7.3 to 16.7) for all CAD events, and 9.2 (4.9 to 17.3) for non-fatal myocardial infarction and death. The coronary calcium score predicted CAD events independently of standard risk factors and CRP (p = 0.004), was superior to the Framingham risk index in the prediction of events (area under the receiver-operating characteristic curve of 0.79 +/- 0.03 vs. 0.69 +/- 0.03, p = 0.0006), and enhanced stratification of those falling into the Framingham categories of low, intermediate, and high risk (p < 0.0001). The electron beam CT coronary calcium score predicts CAD events independent of standard risk factors, more accurately than standard risk factors and CRP, and refines Framingham risk stratification.Journal of the American College of Cardiology 07/2005; 46(1):158-65. · 14.09 Impact Factor