This month in the Journal of the American College of Cardiology: Imaging [JACC-Img], there were three pivotal articles published and one editorial discussion regarding the clinical use of Cardiac CT – two articles dealt with the determination of the coronary artery calcium ‘score’ [CAS – defining what we call the ‘coronary atherosclerotic plaque burden’]. The first paper looked at long term prognosis for fatal and non-fatal heart disease in young military men and women; an editorial was also provided as an overview of the results. The second paper looked at using the changes in the CAS over time to predict worsening of the coronary artery plaque burden. The third paper published looked at the use of contrast enhanced Cardiac CT in terms of CT Cardiac Angiogram [CCTA] – this study showed that people with a totally normal CCTA had virtually NO cardiac events for the next decade.
Pioneers In Cardiac CT
The Princeton Longevity Center is a pioneer in application of Cardiac CT to define the presence, extent, and prognosis for a variety of heart diseases in our clients. As part of our on site [and now on-line] training programs we have taught and continue to teach literally hundreds of cardiologists and radiologists from around the world in independent performance and interpretation of Cardiac CT. We also do thousands of CAS and CCTA scans each year in our three sites: Princeton, NJ; Shelton CT and Fairfax VA.
Dr. Rumberger Commentary on New Cardiac CT Studies
These articles are posted on the website but below I offer some summary comments on each.
JACC-Img 2018: Coronary Artery Calcium and Long-Term Risk of Death, Myocardial Infarction, and Stroke: The Walter Reed Cohort Study
This is a long term [>10 year] follow up of 23,637 military service members who had a baseline CAC scan – none of them, at the time of their initial scan had known heart disease and were considered to be low risk using conventional assessments. The mean age was about 50 years and 77% were men. They examined long term consequences for fatal heart attack, non-fatal heart attack, and/or stroke based on the initial coronary artery calcium ‘score’ [CAS]. The scores were divided into 4 categories [0 or zero – i.e. no calcified plaque; 1-100 – i.e. ‘mild’ plaque; 101-400 – i.e. ‘moderate plaque’; and >401 – i.e. ‘extensive’ plaque]. The results confirmed many prior studies showing that the higher the CAS the more likely for a major cardiovascular event during the follow up period. Also the study showed that CAS strongly predicted CV events regardless of age and number of conventional risk factors. What makes this study so important is that it was done in a generally low-risk group of young adults.
JACC-Img 2018: Coronary Artery Calcium Scoring: Do we need more prognostic data prior to adoption in clinical practice?
In an accompanying editorial for the Walter Reed Cohort study, Dr. Mouaz H. Al-Mallah stated: “The time has come for wide adoption of this important tool to reduce mortality from the numbers one killer of mankind, cardiovascular disease.”
JACC-Img 2018: Coronary Artery Calcium Progression is Associated with Coronary Plaque Volume Progression.
Literally hundreds of prior published research studies have confirmed that the amount of coronary artery calcium defined by non-contrast CT via the CAS correlates directly with the amount of atherosclerotic plaque found at autopsy. At the Princeton Longevity Center we have been using CAS as an initial diagnostic testing and also advocate using the ‘change in CAS’ over time as a surrogate to the progression or even slowing down of plaque progression; thus determining the clinical benefits of lifestyle and medications on the success of our interventions on individual patients. However, this practice has not been universally applied in other practices.
As is known, CAS looks at ‘calcified’ or, in the vernacular ‘hardened’ atherosclerotic plaque; but it is known that there are other types of plaque such as ‘non-calcified’ [i.e. ‘soft’] plaques, mixed [calcified and non-calcified plaque adjacent to each other], and ‘fibrous’ or ‘scarred’ plaques. These together then constitute the total coronary atherosclerotic plaque volume. Many scientists have challenged changes in CAS over time to accurately predict the changes in all plaque types over time.
In the above publication they measured CAS and then quantified the amount of any and all plaque types using quantitative plaque analysis using contrast enhanced cardiac CT or CCTA. They showed that ‘…CAC progression was associated with a significant linear increase in all types of coronary plaque and no plaque progression was observed in subjects without CAC progression.’ They concluded ‘…in a clinical practice setting, progression of CAC [i.e. increases in CAS] was significantly associated with an increase in both calcified and non calcified plaque volume…”
J Am Coll Cardiology Img 2018: Ten-Year Follow-Up After Coronary Computed Tomography Angiography in Patients With Suspected Coronary Artery Disease.
CCTA is now an established non-invasive imaging modality to assess coronary artery disease. In particular CCTA is now advocated as the FIRST test to be considered when otherwise healthy patients presenting to the Emergency Room with chest pains not immediately associated with a heart attack [myocardial infarction]. CCTA looks at the presence of coronary atherosclerotic plaque as a ‘continuum’ from its earliest appearance to the presence of severe unstable plaque or severe focal narrowing of the blood vessels. NO OTHER available imaging modality can do this; furthermore CCTA is the only truly 3-dimensional imaging method to look at heart size, heart function, congenital abnormalities, abnormal cardiac valves, and of course the coronary arteries themselves.
The objective of the above named study was to determine the long-term prognostic power of coronary computed tomography angiography to predict cardiac death and non-fatal myocardial infarction. First of all they showed that the ‘presumed risk’ for heart disease defined using conventional risk factors [such as age, cholesterol, blood pressure, etc.] was ‘reclassified’ in up to 2/3 of patients after defining the true extent of atherosclerotic by CCTA. That is that a low risk person using conventional factors may well be a high risk person after looking at their individual atherosclerotic plaque burden. CCTA then allows one to avoid looking at large ‘population’ derived risk by defining your ‘individual’ risk.
One result in particular showed that a totally normal CCTA [i.e. NO evidence for any type of atherosclerotic plaque] was associated with a totally ‘event-free’ survival over the next decade!