Cardiovascular Risk Assessment—Where Are We Going?

Estimating risk of heart disease is something that clinicians do with one system or another every day in the clinic. The physician obtains a history and performs a physical examination and laboratory data are acquired. The clinician then makes a judgment or calculation about vascular risk and discusses the plan with the patient. A formalization of this approach has worked its way into the guidelines that were promulgated by the National Cholesterol Education Program in 2001. Other regions of the world have adopted similar strategies and guidelines.1,2 What works and what does not work with this approach? First, it should be realized that the initial efforts at putting together risk estimates were derived from observational studies that generally did not intervene, and the prediction algorithms that are used across the United States and Europe are largely based on study participants who are not taking medications that are commonly prescribed today. For instance, the Framingham Heart Study and others that have provided risk prediction algorithms typically include baseline data as far back as the 1970s to fuel the risk engines. Second, patients are not having the same cardiovascular events that they used to have in the past. For example, a large myocardial infarction in an asymptomatic man who has several risk factors and has not recently sought medical advice is not the norm. In the modern era, the patient experiences smaller myocardial infarctions, and the clinical team is monitoring arrhythmia and hemodynamic status as needed. The interventionalists are quick to get involved, and use of thrombolytic agents, stenting, and bypass surgery are occurring earlier in the natural history of atherosclerotic cardiovascular disease than in the past. All in all, the number of severe cardiovascular events, especially unexpected sudden death in previously asymptomatic individuals, is less common than in the past. The existing coronary disease prediction algorithms do not appear to be very good at predicting these modern clinical presentations. A modern criticism of risk prediction is that not all of the newer factors are included in the risk estimation. Would we do better if those factors were included? The answer is generally that we would do a little better if newer tests were included in the screening. Such tests might include evaluating C-reactive protein or other inflammatory markers or a measure of subclinical atherosclerosis such a coronary calcium assessment. The traditional way to assess this approach has been using a multi-variable predictor equation, adding the new variables, and seeing whether prediction has improved. C-reactive protein has been evaluated in this way, and the overall improvement as assessed by C statistics has been modest.3 Selective use of new tests to assess cardiovascular risk has been suggested by several experts. Clinicians have typically followed this line of reasoning to diagnose disease, but there is less experience with this approach of risk assessment. For example, a person with a chest pain history that is suggestive of angina may undergo an exercise test to evaluate symptoms, electrocardiographic results, and cardiac ischemia to make a diagnosis of clinical cardiovascular disease. Using computerized tomography in select individuals will undoubtedly help to identify persons at higher risk for clinical cardiovascular disease. The recent results from the Multi-Ethnic Study of Atherosclerosis (MESA) are highly supportive of this potential,4 but there is little direct experience with this approach for persons undergoing screening. Does screening for cardiovascular disease work across most adult groups? This is a difficult question to address because we lack data. Risk scoring systems tend to overestimate modern-day risk in locales such as Honolulu, Hawaii, China, and Italy, and this experience has been reported in the medical literature.5–7 In the United States, it appears that algorithms largely developed from experience in whites can be used reasonably well in blacks, but the effects of hypertension and left ventricular hypertrophy may be underappreciated with current coronary heart disease risk estimation methods.5 Can a person estimate his or her own risk of coronary heart disease without visiting a doctor?Several recently published projects have addressed this question.8–10 With this approach, the individual can use easily acquired information such as age, sex, height, weight, history of hypertension, history of diabetes, history of abnormal lipids, and family history of heart disease to help predict heart disease risk. Overall, the prediction is not as good as having the information from a formal screening visit, but the cost is very low and these methods may be used as low-cost first steps to help identify persons who might benefit the most from a formal cardiovascular screening visit. Finally, what will happen in the future concerning screening for heart disease? The answer to this question is unknown, but there are indications concerning the directions in which we are going. First, we can now prevent vascular disease outcomes relatively effectively with weight control, smoking cessation, and control of lipids and blood pressure. As a result, there is great interest in the prevention of total cardiovascular disease, which includes coronary heart disease, peripheral vascular disease, and cerebrovascular disease. It is possible that risk assessment for total cardiovascular disease may become a more important target than in the past.9 Second, long-term and lifetime risk of cardiovascular sequelae will be given greater attention than in the past. For example, the average 40-year-old man in Framingham has about a 10-year coronary heart disease risk of only a few percent but has a 50% risk over the rest of his lifetime. Third, we need to incorporate efficient strategies for initial and advanced cardiovascular screening that are efficient, cost-effective, and able to incorporate newer laboratory and imaging science into strategies that will be applicable for preventive cardiology.