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In 1968, Wilson and Jungner1 outlined the 10 key principles for an ideal screening program. To paraphrase this classic article, a screening program should (1) focus on a common, treatable medical condition; (2) use a suitable, cost-effective test that can accurately detect the condition; and (3) lead to an intervention that can reduce complications of the condition without causing adverse effects by applying the intervention to individuals who will not benefit. Cardiovascular disease (CVD) is a common global problem with effective interventions to mitigate life-threatening complications, particularly in symptomatic patients. However, in asymptomatic patients, interventions, such as revascularization, do not prevent complications. Therefore, our traditional screening tools, namely resting and exercise electrocardiography (ECG), fail to meet the key principles Wilson and Jungner1 described years ago and should force clinicians to ask hard questions about whether asymptomatic patients should ever be screened for CVD.
In this week’s issue of JAMA are the updated US Preventive Services Task Force (USPSTF) recommendations2 and evidence report3 regarding screening for CVD using resting and exercise ECG. It is no surprise that the 2018 USPSTF recommendations are similar to the 2012 recommendations. The 2018 recommendations advise against either resting or exercise ECG in patients at low risk for CVD (10-year event risk of <10%) and continue to state there is insufficient evidence to either recommend for or against screening by ECG in patients with intermediate or high risk for CVD (10-year event rate of ≥10%).3 The USPSTF recommendations are consistent with guidelines from other societies, including the American College of Physicians, the American College of Preventive Medicine, and the American College of Cardiology, all of whom do not recommend ECG screening in patients at low risk for CVD.4-8 The Choosing Wisely campaign also has recommendations against screening ECGs in asymptomatic patients at low risk for CVD.
In low-risk patients, screening ECG does not add any important information to conventional risk stratification, comprising a comprehensive history and physical examination, including blood pressure and lipid assessment and screening for diabetes. The addition of ECG information to the standard risk calculators has not reliably reclassified patients into different CVD risk categories, and importantly the addition of ECG data has not led to improvement in cardiovascular outcomes. There are also real downsides to cardiovascular screening. The use of screening ECGs does lead to higher downstream cardiac testing use, more specialist consultations, and potentially higher rates of adverse events, including excess radiation exposure and procedural complications of angiography. For example, in a cohort study of more than 3.6 million patients with low risk for CVD, patients who had a resting ECG were 5 times more likely to receive another cardiac test or consultations with a cardiologist.9 There was also no difference in the 1-year rates of death, revascularization, or hospitalization for a cardiac cause between those who had an ECG and those who did not, with the absolute rate in both groups being less than 0.5%.9 Without clear benefits but with real harms, the evidence is clear that screening ECG should not be a standard part of the risk assessment for asymptomatic, low-risk patients.
More controversial is the use of screening ECG in patients with elevated risk. While the USPSTF recommendations cited a lack of evidence to assess the net benefits vs net harms of screening ECG in this patient cohort, the value add of ECG to existing risk stratification is likely marginal. In these individuals, the incremental value of the ECG findings would likely not be reclassification of CVD risk, but rather the detection of flow limiting coronary artery disease for the purpose of revascularization. In asymptomatic individuals, however, revascularization does not lead to improved cardiovascular outcomes compared with medical therapy.10 Moreover, in patients with a history of revascularization, the American College of Cardiology recommends against routine exercise ECG testing in asymptomatic patients owing to a lack of outcome benefit, while exposing patients to the potential risk of procedural harms.6 In asymptomatic patients at elevated risk, the detection of flow limiting coronary artery disease by screening ECG would most likely lead to higher rates of diagnostic angiography and revascularization with limited impact on cardiovascular events but with potentially higher procedural risks.
One lingering question is whether the detection of CVD by screening ECG in elevated-risk individuals will lead to more intensive medical management that could subsequently reduce adverse cardiovascular events later on. The 2013 Appropriate Use Criteria does list stress testing in patients at high risk for CVD as appropriate for the purposes of targeted prevention efforts that could include medical therapy and/or lifestyle modifications.6 To date and to our knowledge, there is currently no evidence to support this hypothesis. The discussion of the 2013 Appropriate Use Criteria does express some concerns regarding the misinterpretation of the Appropriate Use Criteria as a recommendation to conduct screening on large portions of the US population.6 The USPSTF cites the need for studies that will address the incremental value of ECG information on clinical decision making. Such studies should not simply assess the potential incremental benefits of screening on cardiovascular outcomes, but also the potential patient harms, including complications of downstream testing, patient-reported outcomes, and cost-effectiveness. Finally, research specifically looking at the risks and benefits of ECG screening in high-risk occupations, such as pilots or commercial truck drivers, should be undertaken.
Despite substantial evidence advising against screening ECG in asymptomatic patients of all risk groups, the practice still appears widespread. Nonindicated cardiac tests may be used in 12.8% of low-risk patients and 20.2% of high-risk patients, and in our prior study, 21.5% of low-risk patients received a screening ECG.9,11 In both studies, there was substantial ordering variation, up to 40-fold across physician practices. The reasons for this variation are not known, although knowledge gaps, a culture of defensive medicine, and for-profit and generally unnecessary practices, such as executive physical examinations, could certainly play a role. This ordering variation certainly underscores the need for research to understand the root causes of ordering unnecessary cardiac testing and knowledge translation strategies designed to reduce its use, particularly in high-use areas. Finally, it cannot be emphasized enough that the impact of routine ECG use in low-risk patients on downstream health care use is substantial. Prior work has shown routine ECG use leads to tens of thousands of additional consultations and cardiac tests that add to system costs without improving patient outcomes.9
It should be stressed that the avoidance of screening ECG does not abrogate us from our responsibilities to proactively manage cardiovascular risk. Rather, it should help us focus on evidence-based strategies, including blood pressure, lipid and blood glucose management, smoking cessation interventions, counseling regarding diet and exercise, and actively monitoring for signs and symptoms of CVD that may warrant further investigations. It is understandable that physicians want to do anything it takes to prevent a life-altering cardiovascular event in one of their patients, but in our rush to do something we need to be certain we are not inadvertently doing more harm than good.
Corresponding Author: R. Sacha Bhatia, MD, MBA, Women’s College Hospital, Institute for Health Systems Solutions and Virtual Care, 76 Grenville St, Sixth Floor, Toronto, ON M5S 1B2, Canada (email@example.com).
Published Online: June 12, 2018. doi:10.1001/jamainternmed.2018.2773
Conflict of Interest Disclosures: Dr Bhatia is the recipient of a clinician scientist award from the Heart and Stroke Foundation of Canada and is the Women’s College Hospital F.M. Hill Chair in Health Systems Solutions.
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Bhatia RS, Dorian P. Screening for Cardiovascular Disease Risk With Electrocardiography. JAMA Intern Med. Published online June 12, 2018. doi:10.1001/jamainternmed.2018.2773