Coronary heart disease (CHD) is the leading cause of death in the United States in both men and women, accounting for nearly 40 percent of all deaths each year. Each year, more than 1 million Americans experience nonfatal or fatal myocardial infarction (MI) or sudden death from CHD. Although angina is a common presenting symptom of CHD, in some persons the first manifestation of CHD is MI, sudden death, or another serious cardiovascular event. The risk for incident CHD in asymptomatic persons can be predicted based on the "traditional" risk factors included in the Framingham risk score (age, sex, blood pressure, serum total cholesterol level, low-density lipoprotein [LDL] or high-density lipoprotein [HDL] cholesterol level, cigarette smoking, and diabetes). However, these factors do not explain all of the excess risk. Consequently, there has been a long-standing interest in supplementing traditional risk factor assessment with other methods of screening for CHD, including resting or exercise electrocardiography (ECG). Abnormal findings on ECG might identify those at higher risk of CHD events who would not be identified based on traditional risk factors alone. For example, based on the Framingham risk scoring system, persons at intermediate risk are typically defined as having a 10 to 20 percent risk for CHD death or nonfatal MI over 10 years. Abnormal findings on resting or exercise ECG could reclassify some of these persons as low risk (10-year risk less than10 percent) and others as high risk (10-year risk greater than 20 percent). Such reclassification, if accurate, could guide use of more aggressive cardiovascular risk reduction therapies in persons reclassified as high risk, which might reduce future CHD events.6 However, direct evidence showing benefits associated with implementation of such strategies is lacking, and the classification thresholds remain somewhat arbitrary. The U.S. Preventive Services Task Force (USPSTF) last reviewed the evidence on screening for CHD with resting or exercise ECG in 2004. The USPSTF commissioned an update of the evidence review in 2009 in order to revisit its recommendation on screening with resting or exercise ECG. The purpose of this report is to systematically evaluate the current evidence on whether screening asymptomatic adults for CHD with resting or exercise ECG improves clinical outcomes, affects use of risk reduction therapies, or results in accurate reclassification into different risk categories. This report also systematically reviews the evidence on harms associated with screening. In addition to including new evidence, this report differs from earlier USPSTF reviews by focusing on studies that assessed the usefulness of screening after adjusting for traditional cardiovascular risk factors, in order to better understand the incremental value of resting or exercise ECG. In addition, we performed meta-analysis on the association between selected resting and exercise ECG abnormalities and subsequent cardiovascular events.The investigators, USPSTF members, and Agency for Healthcare Research and Quality (AHRQ) Medical Officers developed the scope and key questions used to guide this review. The analytic framework shows the key questions used to guide the review. Key Question 1. What are the benefits of screening for abnormalities with resting or exercise ECG compared with no screening on CHD outcomes? Key Question 2. How does the identification of high-risk persons via resting or exercise ECG affect use of treatments to reduce cardiovascular risk? Key Question 3. What is the accuracy of resting or exercise ECG for stratifying persons into high-, intermediate-, and low-risk groups? Key Question 4. What are the harms of screening with resting or exercise ECG?