Unanswered and most frequently asked questions from our CACS webinar

Our online presentation, Getting to the heart of, was held on Tuesday 22 February, 2022. Here are the answers to the questions that were submitted by our attendees.

Unanswered and most frequently asked questions from our CACS webinar

Our online presentation, Getting to the heart of, was held on Tuesday 22 February, 2022. Here are the answers to the questions that were submitted by our attendees.

If a high calcium score is calculated, do you refer for a CT coronary angiography (CTCA) next? 

No, a CTCA is only necessary if symptoms exist. You can instead consider a stress test, either MEBi Nuclear scan (which GP’s can refer) or stress echocardiogram.  

It is important to note that the calcium score is a robust marker of cardiovascular risk to advise patients if moderate, aggressive, or no statin therapy is required. If the 10-year risk is 7.5-20%, moderate statin therapy is recommended. If greater than 20% then intensive therapy is required.  

If the calcium score is greater than 100, aggressive statin therapy is required. If greater than 400 then aggressive statin therapy and a functional test is required. 

The MESA (Multi-Ethnic Study of Atherosclerosis) risk score calculator does not cater for people of subcontinent race, is there an alternate calculator you can suggest for this ethnic group?  

There is the modifiable Interheart score for South Asians, with less data, however South Asians have earlier and more severe vascular disease due to diabetes mellitus, obesity and other metabolic syndromes and should be screened and treated as such. 

What screening tool would you use in someone under 45 years if the CACS (Coronary Artery Calcium Scoring) is unreliable due to soft plaque? 

The MESA calculator is most appropriate for individuals 45 years and over. CACS is rarely performed in younger age groups because a zero score is unreliable for those under 50 years. A functional test is adequate to exclude a significant lesion in 80% of cases. CTCA has a 98% efficacy but needs informed consent due to contrast risk. If symptoms exist, there is a need for a CTCA. 

What is the radiation dose during a CTCA? 

< 3.5mSV equivalent to normal background radiation dose at sea level in 1 year. 

Are cardiologists moving away from stents and instead performing Rotablation? 

Rotablation is only used to get through lesions which are heavily calcified, where the usual wire and balloon cannot be passed. Once the rotablation drill has opened the vessel, a stent will follow. 

On what frequency should a calcium score be done?  

Every five years if zero. Every two years if monitoring progress on treatment. 

You mentioned that it is not worth doing a CACS in a 60-year-old diabetic. Could it be worth doing in a 50-year-old asymptomatic type 2 diabetic male keen to define his CVD risk?  

It is important to know that diabetics often have silent ischemia and therefore if not on therapy, should have at minimum a calcium score with a functional test or the gold standard, a CTCA. Limitation of CACS is that it is a measure of calcified plaque only and in patients with other risk factors one is more concerned about detecting and early prevention of soft plaque.  

Is CTCA the only test for patients already stented for progress review? 

No. A functional test has 80% chance of detecting a problem with myocardial perfusion. The time period is important because slow forming narrowing’s often develop collaterals which may be adequate. 

FH (Familial hypercholesterolemia) level Cholesterol, but no family history and CACS is equal to zero, what would you recommend?  

The course of action will depend on the age of the patient and the age of family event in particular. You cannot rely on CACS alone to rule out disease, however it is useful as a baseline.  A CACS of zero is not enough to give a complete clearance. You could do a functional test which would be very reassuring but likely needs to be repeated every two years. The CTCA is also an alternative. 

If a patient with intermediate or high CVD risk is not tolerating statins, can a zero-calcium score inform the decision to cease statins?  

This is a situation where it would be helpful to know if there is any soft plaque present before stopping statins and CTCA is the most powerful tool for this. Unfortunately, without symptoms it is not covered by Medicare.  

The alternative is to refer your patient to a cardiologist for functional testing and clinical review. A cholesterol above 7.5 fulfills the Australian guidelines for statin therapy and a functional test. 

Can one have a heart attack within 12 months of CACS score of less than 50? 

Yes, but it is much less probable. Beware of patients with other high-risk factors. Calcified plaque is stable, soft plaque is at risk of rupture. CACS measures probability of event based on MESA risk calculator and is a measure of calcified plaque only. I see about 5% of patients with a CACS zero who do have some soft plaque.  CACS zero is reliable in 95% (1/20 gets it wrong in the higher risk patients). 

Statins increase the calcium score, so how does one assess an increase in score in a patient on statin in relation to disease progression?  

The increased CACS reflects the soft plaque calcifying and is a good thing. If the CACS increases by over 100 in 24 months, that is too high and may indicate failure of response. 

If ordering a CTCA, do radiologists prefer us to prescribe beta blockers before an appointment? 

50mg the night before and 50mg an hour before, can help to keep heart rate optimal, however this depends on the supervising radiologist/cardiologist. In my practice, I prefer to get the patient in an hour before appointment to get heart rate down and I often use IV Betaloc which is short acting and often more effective. In some situations, Coralan is the better drug e.g. asthmatics, and on my particular machine I scan heart rates up to 130bpm, even in atrial fib and still get diagnostic studies so I would be much gentler with B blocker use. 

If you have an asymptomatic 55-year-old male with a MESA score of 25%, what, if any, test would you consider next? 

I would recommend aggressive statin therapy and a functional test. Intervention is all dependent on symptoms so I would recommend a functional test.