The “Incidentaloma”
As coronary artery calcium (CAC) CT scans have emerged over the past several decades as a superior preventive screening tool for ASCVD risk assessment, much attention has been given to how to address other “incidental” findings such as lung nodules, tumors or other suspicious lesions. In the medical parlance, we call such findings “incidentalomas”.
However not a lot of attention has been given (until perhaps recently) about “incidental” CAC found on non-cardiac Chest CT scans.
Flying Under the Radar
Why do these cases go undertreated?
Hardly a day goes by in the preventive cardiology clinic where a savvy provider cannot find “new” incidental CAC on a Chest CT when seeing a patient in consultation for the first time.
As preventive specialists, we use this “trick” frequently to help identify advanced atherosclerosis and to justify intense preventive therapies.
Sadly, these findings are often not mentioned by the Radiologist in the report. When they are, they are frequently not included in the “Impression,” which is where most referring providers quickly jump to when reviewing the final report. But even when something like “vascular calcifications” or “atherosclerosis” does make it into the “Impression” of a radiographic report, the diagnosis is seldom entered into the patient’s problem list. This means that more often than not, despite detecting the disease, the patient is not informed of the diagnosis of atherosclerosis, nor referred to a specialist for appropriate management.
Years later, when it does eventually get discovered (hopefully not following an ASCVD event), it can represent a frustrating moment for the patient, who’s left asking (appropriately) “you mean it was in my chart all along and nobody told me? Why?”
It’s a welcome surprise then, when a patient is referred by another specialist after discovering atherosclerosis on some unrelated imaging study. It doesn’t have to be a Chest CT. It may be MRI surveillance for prostate cancer, or vascular calcification seen on an ankle x-ray or mammogram (Vascular Calcifications Seen on Mammography: An Independent Factor Indicating Coronary Artery Disease - PMC).
The identification of coronary or other atherosclerosis is the critical first step in getting patients into the right treatment pathways which may prevent atherosclerotic death or serious life-altering complications.
A checklist of targeted recommendations based on published guidelines
For those who don’t already have a diagnosis of ASCVD or coronary atherosclerosis you may want to look into the following:
- Prior CT Chest reports in your medical record
- In the “SUMMARY” or in the body of the report under “HEART” was the presence or absence of coronary artery calcification or atherosclerosis mentioned?
- Yes
- If present:
- Was it qualitatively assessed (mild, moderate, severe)?
- Was a follow up dedicated CAC CT offered to quantitatively help guide :
- Intensity of lipid lowering therapy?
- The need for aspirin?
- Follow up dedicated CAC CT’s may be indicated if it is likely to alter management (NLA Guidelines):
- Has treatment been offered or discussed?
- If not, bring this to the attention of your provider
- If so, has this been reviewed by a cardiometabolic specialist? (future link to such specialists)
- If absent:
- Awesome! That makes it less likely that CAC is present, or at least not severe
- Caveat: standard Chest CTs are not “gated.” “Gating” is where they time the picture taking between beats of the heart, so it’s not blurry. Therefore, nongated studies may miss some coronary artery calcification.
- If risk factors present, consider dedicated CAC CT
- No
- Bring this to the attention of your provider so they can either
- review the films personally, if qualified
- Refer to a cardiometabolic specialist who can perform a comprehensive review, if indicated
- Address this with the Radiology group as a quality initiative
- Consider a CAC CT to formally assess, if indicated
- Typically anyone over the age of 40 or 45 with at least 1 additional risk factor
- Patients younger than 40 with multiple risk factors may be considered for CAC testing at the discretion of their provider
Going into detail on the evidence behind the recommendations and history of treatment for this phenotype.
CAC Reporting
While it might be the first time anyone addressed this finding with the patient and appropriately updated the problem list, this isn’t actually a “new” finding. It was there all along - buried in the medical record in the form of 1’s and 0’s. The “data” exists, but a human practitioner was never aware. In many cases the fist-sized organ in the left center chest, called the heart, is either ignored completely, or a passing comment is made about its size (normal, enlarged) etc. But occasionally (getting better) the Radiologist will make note of the presence of “coronary artery atherosclerosis” and place it in the body of the reports under “HEART.” But it rarely ends up in the summary interpretation, which is often the only place the referring provider looks to find the key elements of the report.
The Society of Cardiac CT and the Society of Thoracic Radiology recommend at least qualitative (mild, moderate, severe) reporting of CAC on all CT scans of the chest (Class I recommendation).
Failure to report CAC on Chest CT represents a “missed opportunity” to identify advanced atherosclerosis and implement preventive measures (Incidental Coronary Calcium on Non-Gated CT Scans of the Chest: A Stepwise Approach to Addressing Underreporting and Implementing Deep Learning - Journal of Clinical Lipidology).
Reporting of incidental CAC has been demonstrated to increase awareness and statin utilization (Incidental Coronary Artery Calcium: Opportunistic Screening of Previous Nongated Chest Computed Tomography Scans to Improve Statin Rates (NOTIFY-1 Project) | Circulation).
Formal CAC Testing For Incidental CAC on Chest CT
The National Lipid Association Scientific Statement on coronary artery calcium scoring states it’s reasonable to proceed with formal CAC CT scoring for when qualitatively mild CAC is seen on non-dedicated chest CT (The National Lipid Association scientific statement on coronary artery calcium scoring to guide preventive strategies for ASCVD risk reduction - Journal of Clinical Lipidology).
It states that qualitatively “moderate or severe calcification generally correlates with a CAC score of >100, a guideline-based indication for statin benefit.”
However, elsewhere in the NLA guidelines, it states “A CAC score > 300 is associated with proportionately higher ASCVD risk than those with scores >100, a finding suggesting benefit from greater LDL-C lowering.
It further states that A CAC score >1000 is associated with an annual risk similar to that of the placebo group in the FOURIER trial, a finding consistent with the potential value of very aggressive LDL-C lowering along with other ASCVD risk reduction strategies.
Thus, there may be utility, in terms of guiding aggressiveness of LDL-C lowering, for formal CAC assessment in all cases of incidental CAC on CT Chest, if it will alter management.
On the other hand, if the decision has already been made to maximally treat an individual patient with very aggressive LDL-C lowering, formal CAC CT imaging may not provide any additional value
Perhaps repeat formal testing will soon be unnecessary if deep learning (DL) algorithms can be used at the time of a non-gated (gating means images are acquired when the heart is relaxed between beats) CT scan. This study showed that DL-CAC > 100 was associated with higher all-cause death and adverse cardiovascular outcomes compared to traditional risk factors (Association of Coronary Artery Calcium Detected by Routine Ungated CT Imaging With Cardiovascular Outcomes).