Tag Archives: ASCVD

Coronary Artery Calcium Scan Embraced By New AHA/ACC Cholesterol Guidelines: Will Insurance Coverage Follow?

The skeptical cardiologist has been utilizing coronary artery calcium (CAC) scans to help decide which patients are at high risk for heart attacks, and sudden cardiac death for the last decade. As I first described in 2014, (see here) those with higher than expected calcium scores warrant more aggressive treatment and those with lower scores less aggrressive treatment.

Although , as I have discussed previously, CAC is not the “mammography of the heart” it is incredibly helpful in sorting out personalized cardiovascular risk. We use standard risk factors like lipids, smoking, age, gender and diabetes to stratify individuals according to their 10 year risk of atherosclerotic cardiovascular disease (ASCVD) but many apparent low risk individuals (often due to inherited familial risk) drop dead from ASCVD and many apparent high risk individuals don’t need statin therapy.

Previously, major guidelines from organizations like the AHA and the ACC did not recommend CAC testing to guide decision-making in this area. Consequently, CMS and major insurers have not covered CAC testing. When my patients get a CAC scan they pay 125$ out of their pocket.. For the affluent and pro-active this is not an obstacle, however those struggling financially often balk at the cost.

I was, therefore, very pleased to read that the newly updated AHA/ACC lipid guidelines (full PDF available here) emphasize the use of CAC for decision-making in intermediate risk patients.

 

 

 

 

 

 

 

 

For those patients aged 40-75 without known ASCVD whose 10 year risk of stroke and heart attack is between 7.5% and 20% (intermediate, see here on using risk estimator) the guidelines recommend “consider measuring CAC”.

If the score is zero, for most consider no statin. If score >100 and/or >75th percentile, statin therapy should be started.

I don’t agree totally with this use of CAC but it is a step forward. For example, how I approach a patient with CAC of 1-99 depends very much on what percentile the patient is at. A score of 10 in a 40 year old indicates marked premature build up of atherosclerotic plaque but in a 70 year old man it indicates they are at much lower risk than predicted by standard risk factors. The first individual we would likely recommend statin therapy and very aggressive lifestyle changes whereas the second man we could discuss  taking off statins.

Neil Stone, MD, one of the authors of the guidelines was quoted  as saying that the imaging technique is “the best tiebreaker we have now” when the risk-benefit balance is uncertain.

“Most should get a statin, but there are people who say, ‘I’ve got to know more, I want to personalize this decision to the point of knowing whether I really, really need it.’ … There are a number of people who want to be certain about where they stand on the risk continuum and that’s how we want to use it,”

Indeed, I’ve written quite a bit about my approach to helping patients “get off the fence” on whether or not to take a statin drug.

I recommend reading “Are you on the fence about taking a statin drug” to understand the details of using CAC in decision-making and the follow up post on a compromise approach to reducing ASCVD risk.

Deriskingly Yours,

-ACP

Full title of these new guidelines includes an alphabet soup of organization acronyms

2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Blood Cholesterol

N.B. For your reading pleasure I’ve copied the section in the new guidelines that discusses in detail coronary artery calcium.

Two interesting sentences which I’ll need to discuss some other time

-When the CAC score is zero, some investigators favor remeasurement of CAC after 5 to 10 years

CAC scans should be ordered by a clinician who is fully versed in the pros and cons of diagnostic radiology.

In MESA (Multi-Ethnic Study of Atherosclerosis), CAC scanning delivered 0.74 to l.27 mSv of radiation, which is similar to the dose of a clinical mammogram 

-4.4.1.4. Coronary Artery Calcium

Substantial advances in estimation of risk with CAC scoring have been made in the past 5 years. One purpose of CAC scoring is to reclassify risk identification of patients who will potentially benefit from statin therapy. This is especially useful when the clinician and patient are uncertain whether to start a statin. Indeed, the most important recent observation has been the finding that a CAC score of zero indicates a low ASCVD risk for the subsequent 10 years (S4.4.1.4-1–S4.4.1.4-8). Thus, measurement of CAC potentially allows a clinician to withhold statin therapy in patients showing zero CAC. There are exceptions. For example, CAC scores of zero in persistent cigarette smokers, patients with diabetes mellitus, those with a strong family history of ASCVD, and possibly chronic inflammatory conditions such as HIV, may still be associated with substantial 10-year risk (S4.4.1.4-9–S4.4.1.4-12). Nevertheless, a sizable portion of middle-aged and older patients have zero CAC, which may allow withholding of statin therapy in those intermediate risk patients who would otherwise have a high enough risk according to the PCE to receive statin therapy (Figure 2). Most patients with CAC scores ≥100 Agatston units have a 10-year risk of ASCVD≥7.5%, a widely accepted threshold for initiation of statin therapy (S4.4.1.4-13). With increasing age, 10- year risk accompanying CAC scores of 1 to 99 rises, usually crossing the 7.5% threshold in later middle age (S4.4.1.4-13). When the CAC score is zero, some investigators favor remeasurement of CAC after 5 to 10 years (S4.4.1.4-14–S4.4.1.4-16). CAC measurement has no utility in patients already treated with statins. Statins are associated with slower progression of overall coronary atherosclerosis volume and reduction of high-risk plaque features, yet statins increase the CAC score (S4.4.1.4-17). A prospective randomized study of CAC scoring showed improved risk factor modification without an increase in downstream medical testing or cost (S4.4.1.4-18). In MESA (Multi-Ethnic Study of Atherosclerosis), CAC scanning delivered 0.74 to l.27 mSv of radiation, which is similar to the dose of a clinical mammogram (S4.4.1.4- 19). CAC scans should be ordered by a clinician who is fully versed in the pros and cons of diagnostic radiology.

Downloaded from http://ahajournals.org by on November 11, 2018

from Grundy SM, et al.
2018 Cholesterol Clinical Practice Guidelines

Doctor, My Cholesterol Levels Are Good. Why are You Starting a Statin?

I get this question frequently from patients.

It is a reasonable question. If statins are a treatment for abnormally high cholesterol levels why would we start them on a patient with normal or low levels.

ather_lowresThe answer is that we are not concerned with cholesterol levels. What we are concerned with is atherosclerotic cardiovascular disease (ASCVD) and its downstream consequences including heart attack and stroke.

Thus, the new guidelines recommend  calculating a patient’s 10 year risk of heart attack and stroke due to ASCVD ( see here for my discussion of smart phone app that makes this calculation) and if it is over 7.5% to consider starting a statin drug to reduce ASCVD risk.

Cholesterol is just one of many factors that effect the risk but we know that irrespective of cholesterol level, starting a statin will substantially lower the risk.

A patient  who has smoked   cigarettes lifelong  asked me this question recently.

When I plugged the patient’s excellent cholesterol values into the ASCVD app, the 10 year risk of heart attack or stroke was quite high, 14.9%. Bad cholesterol  (LDL) was 90, well below what is considered optimal. Good cholesterol (HDL) was 60, well above what is considered optimal.

Studies have demonstrated that even patients with cholesterol numbers this good benefit from statin therapy. Their risk of heart attack and stroke will be substantially reduced over time.

My patient has not yet had a heart attack or stroke and it is likely that despite engaging in the extremely damaging behavior of cigarette smoking , the genetically programmed excellent cholesterol values have somewhat protected from ASCVD.

However, a vascular screening study has demonstrated  that  early atherosclerotic plaque in both the patients carotids. The patient has ASCVD and it is only a matter of time if the patient keeps smoking before the patient  has a clinical event related to it.

I told my patient that if he/she stopped smoking cigarettes his/her estimated 10 year risk would drop to 9.7% and I would not recommend statin therapy.

We discussed methods to help quit and the patient indicated that the patient would start  using a nicotine patch and try to quit in the next few months.

Unfortunately, at follow up smoking was ongoing.

Thus, my recommendation to start statin therapy despite her excellent cholesterol values.

Other groups of patients besides cigarette smokers can have advanced or premature ASCVD with excellent or “normal” cholesterol values. Diabetics often have low bad cholesterol values associated with low good cholesterol and high triglycerides.

Sometimes, ASCVD develops prematurely even in patients who have a low 10 year risk based on standard risk factors. This is usually in patients with a strong family history of ASCVD who have an inherited atherogenic abnormality of lipid metabolism that is not manifested in the standard cholesterol parameters (see Dealing With the Cardiovascular Cards You’ve Been Dealt).

To identify these patients a search for subclinical atherosclerosis by vascular screening or coronary calcium scan is necessary. When advanced plaque is identified statin therapy is often warranted even with a low estimated 10 year risk and normal cholesterol values.

So some patients can have very high cholesterol values and I don’t recommend any therapy, some have low and I do. I’m much more focused on the presence or absence of ASCVD in my treatment decisions.

Ultimately we are not treating “high cholesterol” when we start cholesterol lowering therapy we are working to prevent or slow the progression of ASCVD,

-atherosclerosis is still my psychosis

-ACP