More Fact Checking
Following the death of Australian Ironman Dean Mercer (August 2017), I was interviewed on ABC radio in Brisbane and made the comment that the common health checks for BP and cholesterol were not the best predictors of heart attacks. I then suggested (something I have been saying for years) that coronary calcium scoring was the best indicator of heart attack risk.
I have made these comments on multiple occasions because the scientific evidence is very solid in support of this statement. So, I was somewhat surprised when an article was released recently from a group known as RMIT ABC fact check. I presume from the title the author is representing RMIT and am not sure if there is any affiliation with the ABC.
I thought I would therefore do my own fact check on the article but suffice to say I do agree with many of the comments made by the other experts in the field who were interviewed.
It is certainly true that I pioneered coronary artery calcium scoring in the late 1990s in conjunction with the Sydney Adventist Hospital, but also with Dr David Grout, another senior cardiologist. The service was offered after two years of painstaking research and overseas travel, visiting world experts in the area and facilities offering this service. Even back then the research was extremely compelling demonstrating the robust nature of coronary calcium scoring as a better predictive test for heart disease risk than high cholesterol or high blood pressure. Since, there have been multiple studies to back up this statement.
The report by RMIT ABC fact check then went on to suggest that there was more to the story than I claimed in the interview. The article agrees with my claims that “coronary calcium scans are able to identify heart disease in patients, with resulting calcium scores having been found to correlate with future cardiovascular events. The Cardiac Society of Australia and New Zealand describes the test as a robust way to estimate future risk of cardiac events.”
But then they mention a subcommittee of the Australian health minister’s advisory council suggesting the test is of unproven clinical benefit or utility. This is despite the fact that there are now multiple studies to the contrary. There was also a bizarre comment from the subcommittee raising concerns about the radiation dose. This is where Fact check and this subcommittee are seriously wrong. They are looking at a test known as intravenous coronary CT angiography which can be anywhere between 50 to 300 chest x-rays of radiation based on the protocol and scanning machine used. With the new scans and different protocols, even with intravenous CT coronary angiography, the radiation dose is much less. Modern coronary calcium scoring would only deliver somewhere between 5 to 10 chest x-rays of radiation per scan which has minimal impact on any long-term radiation associated risk.
The final comment made in this article before interviewing other experts in the area was that the Cardiac Society of Australia & New Zealand suggested that only people of a certain age and at intermediate risk of heart disease or a strong family history of heart disease should undergo a calcium scan. I, however, suggest that all men over 50 and women over 60 should have a coronary calcium scan. The reality here is that the vast majority of people at the age I have suggested do have at least one risk factor for coronary artery disease, often prompting a medical practitioner to commence treatment. The ages I suggested are a good benchmark because it is a well-known fact that 50% of 50 year old males & 60 year old females have some degree of coronary calcium.
As one example, a trial published in the November 2015 Journal of the American College of Cardiology followed 5000 people over the age of 50 for 10 years. 77% of the people in this trial fitted the US criteria to be commenced on a statin for hypercholesterolaemia. Half of this number had a zero coronary calcium score and the conclusion of the trial was that statins are of no use to people with zero calcium scores.
A trial published a few months ago suggested that commencing statin therapy in people over the age of 65 without clinical heart disease, regardless of cholesterol levels, actually increased death rate.
Another trial published in 2016 in the British Medical Journal reviewed 68,000 people followed for 10 years and found that in people without existing heart disease over the age of 60, there was no link between the so-called bad cholesterol LDL and coronary artery disease. The striking finding from this trial, however, was that the higher your LDL over the age of 60, the lower your death rate, the less cancer you suffered along with lower rates of gastrointestinal disease and infections.
Surely we need a better test than cholesterol levels to predict heart disease risk and in fact, we have had this test for around 20 years i.e. coronary calcium scoring. One of the major problems with coronary screening over the past 5 to 10 years has been adopting intravenous CT coronary angiography as a screening test for heart disease risk. There are no scientific studies whatsoever in asymptomatic patients to demonstrate intravenous CT coronary angiography as a better predictor for heart disease risk than standard coronary calcium scoring. But, there is no doubt that in almost all cases (depending on the scanning machine and protocol used) that intravenous CT coronary angiography delivers much higher radiation doses, it always does require an intravenous injection of contrast medium which may lead to an allergic reaction and does make your wallet, in most cases, $500 lighter.
Three of the four other experts completely agree with me that calcium scoring was a better predictor of heart disease risk than the standard risk factors of high cholesterol and high blood pressure. One of the people interviewed, Prof Stephen Nicholls agreed with me that coronary calcium scoring had been shown in some people to improve risk prediction but then urged caution in promoting its widespread use. He stated there is no data at all showing that having a calcium score leads to changing treatment or outcome. This is not actually true. Prof Alan Taylor in the US did perform a study to show that people knowing their calcium score actually changed behaviour & also knowing coronary calcium scores leads to change in therapy. A low score will often see patients appropriately stopping unnecessary treatment, whereas high scores will lead to more aggressive risk factor modification. This is clearly demonstrated in the 2015, JACC article quoted above in regard to unnecessary statin therapy for people with a zero calcium score — a definite outcome change when you can avoid long term drug therapy for people who don’t need it.
Can I also point out that there are no studies to demonstrate that treating high cholesterol with statins in people who are deemed at low risk demonstrates any long-term benefits whatsoever, but doctors continually seem to do this with little evidence?
Prof Nicholls also made the point that “predicting the risk of heart attacks is not easy. There are likely to be other causes of heart disease that we know less about and that tests are not available for”. In other words, no test is perfect. Who is suggesting that? Prof Nicholls also made the comment coronary calcium scoring for people with existing heart disease is a worthless test as it is a diagnostic test for heart disease. If you already have heart disease, there is clearly no point in having the test and I’ve never made any claims to the contrary.
At no stage did I suggest coronary calcium scoring is a perfect test nor does it predict everyone at risk for heart disease. All I suggested was that coronary calcium scoring was a more predictive test than standard risk factors.
Finally, Fact Check stated another reason not to do calcium scores is because it lacked official backing. There were no references to coronary calcium scoring on the Heart Foundation website and then they revisited the subcommittee of the Australian health ministers who did not recommend the test. I’ve often stated that science advances “funeral by funeral” and until conservative members of the medical profession start to analyse the already existing data to support this very good test we will continue to see one person die every 12 minutes from heart disease in this country alone.
