The intention of most health screening programs is to identify people who have a certain disease or condition early in the disease course, in order to treat them promptly and cure the problem or minimize its impact. Yet like anything begun with good intentions, screening too can turn bad. In this week's podcast, Rick and I talk about just such a circumstance: screening the arteries of the heart using CT in a group of people at low risk for heart disease, published in the current issue of Archives of Internal Medicine. Several of the study authors are also our colleagues at Johns Hopkins.
The study population consisted of 1000 people who underwent CT screening of their coronary arteries (those that supply the heart itself with blood) compared with 1000 matched controls whose heart arteries were not examined this way. The technique used for examination is known as coronary computed tomographic angiography or CCTA.
Medication use in both groups, referrals for additional testing to assess the heart, procedures to improve blood supply to the heart (revascularization), and heart-related events were assessed in both groups at 90 days and 18 months. Those participants who had had CCTA were subsequently put on aspirin or statin medications more, and underwent more secondary testing and revascularization procedures than those who did not. Yet for all that, there was no difference in cardiac events at 18 months. The authors conclude, and we agree wholeheartedly, that the additional risk and expense of CCTA is not justified in those at low risk for coronary artery disease.
What are the risks of CCTA? These would include the risk of radiation exposure and that of the administration of a contrast agent to help improve visualization of the arteries. Some people have very dramatic and sometimes life-threatening reactions to contrast agents. So in summary, people who are at low risk for coronary artery disease shouldn't elect this screening test.
I do query Rick in the podcast, however, on use of tools like the Framingham risk score, to hone in on someone's cardiovascular risk. We agree that since heart disease is the number one cause of death, some assessment is appropriate. And it would be really great to find a low-risk, easily administered and available screening tool. Yet even such as these are not without consequence. Consider the case of prostate specific antigen (PSA) screening for prostate cancer.
PSA screening is widely available, requires a blood sample, is reliable and easily administered. Yet harsher critics among us would likely suggest that wholesale PSA screening has been largely responsible for overtreatment of prostate cancer, with its host of negative consequences, including urinary incontinence and sexual dysfunction. For the majority of men who have prostate cancer, the disease will not kill them. Rather they are likely to die with the disease rather than of it.
With regard to coronary artery disease, for now, the best advice seems to be if you're in a low risk group, congratulations! Continue to shun smoking, watch your weight and diet, exercise regularly, keep blood pressure under control and know your family history of heart disease.
Other topics this week include lung remodeling in asthma in NEJM, a comparison of stroke rehabilitation methods in the same journal, and comparison of aspirin with a new agent for prevention of second stroke in the Lancet. Until next week, y'all live well.