{"id":1455,"date":"2010-03-10T21:09:48","date_gmt":"2010-03-11T02:09:48","guid":{"rendered":"http:\/\/blogs.nejm.org\/cardioexchange\/is-the-patient-selection-process-for-cardiac-cath-broken\/"},"modified":"2011-07-19T17:45:15","modified_gmt":"2011-07-19T21:45:15","slug":"is-the-patient-selection-process-for-cardiac-cath-broken","status":"publish","type":"post","link":"https:\/\/blogs.nejm.org\/cardioexchange\/2010\/03\/10\/is-the-patient-selection-process-for-cardiac-cath-broken\/","title":{"rendered":"Is the Patient-Selection Process for Cardiac Cath Broken?"},"content":{"rendered":"

We welcome Pamela S. Douglas, MD, to answer our questions about her research team\u2019s<\/em> <\/em>NEJM study<\/em><\/a> on the diagnostic yield of coronary angiography. We encourage you to ask yours.<\/em>
\n 
\nBackground: In this observational study of the CathPCI database of the National Cardiovascular Data Registry (NCDR), 38% of about 400,000 patients without known coronary artery disease who underwent elective cardiac catheterization were ultimately found to have obstructive CAD.
\n 
\nDid the patients who had undergone noninvasive testing (84% of your cohort) include those who had a screening catheterization for new-onset cardiomyopathy? If so, could that have biased the results, given that typically about half of such patients have nonobstructive CAD?<\/strong>
\n 
\nWe excluded patients who underwent diagnostic catheterization for cardiac indications other than \u201cto rule out CAD,\u201d as the NCDR describes it. That exclusion comprises an array of cath indications, including cardiomyopathy, that patients may have. Although the NCDR is an observational database and the indications for cath were selected by each site, we suspect that few patients with new-onset cardiomyopathy were in our cohort.
\n 
\nNoninvasive testing added little predictive value to that of clinical risk factors and symptoms in your study. Would such testing have had a better predictive value for obstructive CAD if the analysis had included only patients with stress tests (exercise, nuclear, or echo) and not patients with ECGs, resting echos, or CTs?<\/strong>
\n 
\nOne would certainly hope so, but we simply cannot know for sure. Notably, Bayesian principles tell us that no test performs well in populations whose pretest risk levels are at the extremes. In our study, the low prevalence of obstructive CAD at cath suggests that the noninvasive tests for ischemia were done in a low-risk population. In the unlikely event that all patients who underwent noninvasive tests also went on to catheterization, there would have been, at best, an intermediate probability of disease. In either case, it is impossible to assess the performance of these tests, regardless of the type, using our data.
\n 
\nShould we as practitioners conclude that we\u2019re doing too many useless noninvasive tests and cardiac catheterizations?<\/strong>
\n 
\nThis has been posed as an either\/or choice, but the data make clear that a large number of patients in our study were at low clinical risk (30% were asymptomatic, 29% had low Framingham risk). Given that decisions about whether to proceed to cath begin with a clinical evaluation, it\u2019s at least one of the potential source points for the problem. We do not have adequate data to assess whether the actual ordering of tests and caths also contributes to the problem. In addition, we must remember that a finding of no obstructive CAD can be an important result and is not proof that testing was unnecessary. Plaque rupture generally occurs in patients with nonobstructive CAD, and even a finding that a patient has no lesions at all can be reassuring and may alter care.
\n 
\nWhat policies or practices should change as a result of this study?<\/strong><\/p>\n

We have merely identified a problem; we have not found its cause. More research is needed to identify the optimal practice at each of the decision points that lead up to a diagnostic cath: clinical evaluation and risk assessment, noninvasive test selection and performance, and the decision to proceed to cath. The National Heart, Lung, and Blood Institute has just funded the PROMISE trial<\/a>, in which clinical outcomes following a diagnostic strategy of functional testing will be compared with outcomes after CT angiography in patients with stable chest pain.
\n 
\nFor now, benchmark rates for finding no obstructive disease in a carefully defined elective-cath population could be added to the regular NCDR reports that sites already receive. The sites would be able to use this information to assess and improve their practices. Decision-support tools can also be employed, as David J. Brenner recommends in his editorial. The American College of Cardiology has developed appropriate-use criteria<\/a> for noninvasive testing and revascularization. Such criteria for diagnostic cath might be very helpful in quality-improvement efforts.<\/p>\n","protected":false},"excerpt":{"rendered":"

We welcome Pamela S. Douglas, MD, to answer our questions about her research team\u2019s NEJM study on the diagnostic yield of coronary angiography. We encourage you to ask yours.   Background: In this observational study of the CathPCI database of the National Cardiovascular Data Registry (NCDR), 38% of about 400,000 patients without known coronary artery […]<\/p>\n","protected":false},"author":157,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1,9],"tags":[],"class_list":["post-1455","post","type-post","status-publish","format-standard","hentry","category-general","category-interventional-cardiology"],"_links":{"self":[{"href":"https:\/\/blogs.nejm.org\/cardioexchange\/wp-json\/wp\/v2\/posts\/1455","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.nejm.org\/cardioexchange\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.nejm.org\/cardioexchange\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.nejm.org\/cardioexchange\/wp-json\/wp\/v2\/users\/157"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.nejm.org\/cardioexchange\/wp-json\/wp\/v2\/comments?post=1455"}],"version-history":[{"count":0,"href":"https:\/\/blogs.nejm.org\/cardioexchange\/wp-json\/wp\/v2\/posts\/1455\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogs.nejm.org\/cardioexchange\/wp-json\/wp\/v2\/media?parent=1455"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.nejm.org\/cardioexchange\/wp-json\/wp\/v2\/categories?post=1455"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.nejm.org\/cardioexchange\/wp-json\/wp\/v2\/tags?post=1455"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}