{"id":1019,"date":"2016-04-13T15:05:13","date_gmt":"2016-04-13T15:05:13","guid":{"rendered":"http:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/?p=1019"},"modified":"2017-08-21T10:57:40","modified_gmt":"2017-08-21T10:57:40","slug":"primary-care-corner-with-geoffrey-modest-md-coronary-artery-calcium-scores-from-regular-chest-cts","status":"publish","type":"post","link":"https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/2016\/04\/13\/primary-care-corner-with-geoffrey-modest-md-coronary-artery-calcium-scores-from-regular-chest-cts\/","title":{"rendered":"Primary Care Corner with Geoffrey Modest MD: Coronary Artery Calcium Scores From Regular Chest CTs"},"content":{"rendered":"<p><strong>By Dr. Geoffrey Modest<\/strong><\/p>\n<p>As mentioned in prior blogs (see below), I think the data are quite good for quantitative\u00a0coronary\u00a0artery calcium (CAC) as a marker for future clinical\u00a0coronary artery disease (CAD). But the big issue to me is the excess\u00a0radiation exposure. However, loads of patients are getting chest CTs for a variety of reasons, and a recent article found that CAC scoring on routine chest CTs is quite a good predictor of mortality\u00a0(see J Am Coll Cardiol Img 2016;9:152).<\/p>\n<p>Details:<\/p>\n<ul>\n<li>4,544 community-living people (mean age 68, 63% male) had &#8220;whole-body&#8221; CT scans, which included both\u00a0EKG-gated CTs\u00a0with 3mm cuts for their CAC scores and 6 mm chest CTs. All were done between 2000 and 2003, with mortality follow-up through 2009.<\/li>\n<li>157 people died, and these were matched with 494 controls by sex and age.<\/li>\n<li>Cases and controls were well-matched for BMI, total cholesterol, HDL, and use of lipid-lowering agents. Not so well-controlled for diabetes,\u00a0hypertension, smoking, or family history of CAD, though on review of the numbers, the\u00a0difference in hypertension was not significant<\/li>\n<\/ul>\n<p>Results:<\/p>\n<ul>\n<li>\u200bThe Spearman correlation of CAC scores between the 2 different CT scans was very\u00a0high, at 0.93 (p&lt;0.001), with 1.0 being perfect (at least I am told this correlation is very high, per my son Jake, my local statistician masquerading as a medical student)<\/li>\n<li>The CAC scores were lower in the 6mm vs 3mm CT scans (median of\u00a022 vs 104 Agatston units), with p&lt;0.001<\/li>\n<li>Adjusted for traditional CAD risk factors, for each standard deviation higher, the CAC score on the 6 mm CT scans was associated with a 50% higher odds of death [OR\u00a0=\u00a01.5 (1.2-1.9)], essentially the same as the odds ratio for the dedicated 3 mm CT scan\u00a0[OR\u00a0=\u00a01.5 (1.1-1.9)]<\/li>\n<\/ul>\n<p>So, this brings up a few points:<\/p>\n<ul>\n<li>CAC scores are a strong predictor of CAD events and all-cause mortality, adding predictive value to the Framingham Risk Score (and is usually cited as the best of the &#8220;non-traditional&#8221; risk factors, as per the Am Heart Assn)<\/li>\n<li>The JAMA study in the blog below was an assessment of the Framingham Study participants, which found a 1.6% incidence of CAD over 9.4 years in those with an Agatson score of \u201c0\u201d, even if they were felt to be &#8220;statin-eligible&#8221; by the quite aggressive 2013 ACC\/AHA guidelines).<\/li>\n<li>Though the EKG-gated CTs\u00a0are not generally approved by insurances for coverage and only 600K are done annually in the US, there are &gt;7.1 million chest CTs done annually<\/li>\n<li>It is interesting that regular chest CTs are so very strongly correlated with CT scans done specifically to assess CAC scores, since the latter are\u00a0finer (3mm cuts vs 6mm) and are timed\/gated to the EKG to minimize motion artifact from the beating heart<\/li>\n<li>Many of the huge numbers of chest CTs done are for people who\u00a0are already\u00a0at high risk of CAD (e.g., they smoke or have one or more\u00a0of other CAD\u00a0risk factors which lead to the chest CT). So, it may be\u00a0really useful for the radiologist to comment on the CAC score, in order to help us risk stratify patients for either more or less rigorous clinical\u00a0CAD prevention (e.g., whether to use statins, or perhaps aspirin).<\/li>\n<li>The National Study of Lung Cancer, the study on LDCT which propelled the recommendations to check LDCTs in smokers (see blog below for details and critique), used large numbers of regular high dose\u00a0CTs to check on suspicious lesions (over 3 years,\u00a0of the\u00a026,722 people in that\u00a0study, 18,146 had false positive tests, and 58% went on to regular or PET-CT scans).\u00a0So, with the\u00a0routinization of low dose chest CTs (LDCTs)\u00a0in smokers, there will be many many more regular chest CTs done that could be used to assess CAC scores<\/li>\n<li>One wonders if LDCTs themselves would allow an accurate predictive model for CAD risk assessment through CAC scores. I did speak with a radiologist who said that he could definitely evaluate coronary arteries for calcium on LDCTs. And, since there is such a strong correlation between regular CTs and those done specifically for CAC scoring, LDCT evaluation for CAC would likely be very useful if it turns out the CAC scores for them matched well with those of regular chest CTs<\/li>\n<li>Though\u00a0in the study there was some increase in all-cause mortality in those with a &#8220;0&#8221; on either type of CT scan,\u00a0the data were not granular enough to know what they actually died from.\u00a0It would be really useful to know that: for example, since the 6 mm CT scan could conceivably miss small calcifications, a read of &#8220;0\u00a0Agatston units&#8221; may not have the same low rate of events as a &#8220;0&#8221; with the 3 mmEKG-gated\u00a0scans.<\/li>\n<li>And, there are some concerns about generalizability of the results, since the patients in this study were predominantly non-Hispanic\u00a0white adults, many of whom self-referred for whole-body scans for &#8220;preventive care&#8221;.<\/li>\n<li>So, the relative beauty of this study is that the data are already there, we just need to get the radiologists to read and report it (Currently, CAC on chest CTs is reported only on 44% of chest CTs, and is not quantified). And there really could be very important changes in how aggressive we are in our CAD prevention approach, both increasing and decreasing its intensity depending on the CAC score<\/li>\n<\/ul>\n<p>For more background, see\u00a0<a href=\"https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/2015\/08\/05\/primary-care-corner-with-geoffrey-modest-md-comparison-of-the-2013-accaha-lipid-guidelines-to-atpiii\/\">https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/2015\/08\/05\/primary-care-corner-with-geoffrey-modest-md-comparison-of-the-2013-accaha-lipid-guidelines-to-atpiii\/<\/a> which looks at the actual\u00a0predictive value of CAC scores and the considerable\u00a0overtreatment by the\u00a0new 2013 Am Heart Assn guidelines<\/p>\n<p>There have been several prior blogs on LDCT screening in smokers, for example, see\u00a0<a href=\"https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/2013\/07\/16\/primary-care-corner-with-geoffrey-modest-lung-cancer-screening-with-low-dose-ct-ready-for-prime-time\/\">https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/2013\/07\/16\/primary-care-corner-with-geoffrey-modest-lung-cancer-screening-with-low-dose-ct-ready-for-prime-time\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Primary Care Corner with Geoffrey Modest MD: Coronary Artery Calcium Scores From Regular Chest CTs [&#8230;]<\/p>\n<p><a class=\"btn btn-secondary understrap-read-more-link\" href=\"https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/2016\/04\/13\/primary-care-corner-with-geoffrey-modest-md-coronary-artery-calcium-scores-from-regular-chest-cts\/\">Read More&#8230;<\/a><\/p>\n","protected":false},"author":148,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[14283],"tags":[],"class_list":["post-1019","post","type-post","status-publish","format-standard","hentry","category-archive"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/wp-json\/wp\/v2\/posts\/1019","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/wp-json\/wp\/v2\/users\/148"}],"replies":[{"embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/wp-json\/wp\/v2\/comments?post=1019"}],"version-history":[{"count":0,"href":"https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/wp-json\/wp\/v2\/posts\/1019\/revisions"}],"wp:attachment":[{"href":"https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/wp-json\/wp\/v2\/media?parent=1019"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/wp-json\/wp\/v2\/categories?post=1019"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/bmjebmspotlight\/wp-json\/wp\/v2\/tags?post=1019"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}