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In heart test, the calcium score matters

In heart test, the calcium score matters

The coronary artery calcium score can predict the probability of heart attack in asymptomatic, middle-aged people. So why have we not heard about it?

Coronary Artery Calcium Score reveals the extent of plaque formation and could predict heart attack risk in asymptomatic people

On May 19, 2021, Spencer Goff woke up at his residence in Central Illinois, US, planning to get on with his day and work after his regular morning walk — and get a coronary artery calcium (CAC) scan done as instructed by his family doctor. The 57-year-old US-Navy-nuclear-submariner-turned-commercial-loan-broker considered himself to be as healthy as possible for his age. He took good care of himself — lifting weights and walking five miles a day. He had quit smoking in 1992 and was prompt with his routine medical examinations.

A week earlier, he had even had his blood pressure (110/68) and cholesterol tests, but his doctor suggested he get a CAC scan done as a precautionary measure considering his age and the history of cardiac complications in his family.


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“Never had any signs or symptoms that I was aware of, and really no physical limitations even at my age,” Goff told Happiest Health in an online interaction. “Just two days before the test I had cut down an oak tree in my backyard. I have had multiple electrocardiograms over the years and those were always OK as well. If you look at me and my family and friends’ group, I was the healthy one.”

But the five-minute CAC scan revealed that Goff had a high coronary calcium score (1,938). Subsequent tests ordered by a cardiologist confirmed four severe blockages: a 100 per cent blockage in his left anterior descending artery, a 90 per cent blockage in one and 80 per cent blockage in two other coronary arteries. The cardiologist told him he had an extremely high chance of suffering a massive heart attack.

About a month after getting his coronary calcium score, Goff underwent an emergency quadruple bypass surgery at the Memorial Medical Centre in Illinois on June 21, 2021.

“I am getting back to ‘normal’,” said Goff. “I still haven’t got my stamina back, but it hasn’t even been a year since my surgery. My surgeon made it very clear that if I would have had a cardiac event, I probably wouldn’t have survived it. The only reason that things went as well as they did was because I had surgery before I had a cardiac event and there was no heart damage.”

Cardiac issue despite healthy diet and lifestyle? 

Thousands of kilometres away in Bengaluru, India, entrepreneur HV Balakrishna also benefited from getting a timely CAC scan done. The 59-year-old comes from a family with a history of cardiac complications — five of his eight siblings have been diagnosed with cardiac conditions, and three of them have passed away. In Balakrishna’s case, the calcium score he got in 2012 made him focus seriously on his cardiac health.

“My calcium score was high, and it was the first actual indicator that I had to take care of my cardiac health,” he told Happiest Health. “A healthy diet and lifestyle were already part of my routine. I used to get normal readings on my routine medicals. My doctor had recommended this test because of my family history. I started being extra careful after I got my scan report.”

Balakrishna, who got a bypass done in 2017, now lives a cautious and healthy life with his family in Banashankari in India’s top IT city.

Following a healthy lifestyle and getting normal regular health readings over the years, both Goff and Balakrishna said they had assumed that everything was okay — until they got their CAC scans done and followed up by opting for timely intervention.

A 5-minute test that can predict heart trouble

According to the WHO, cardiovascular diseases claim 17.9 million lives annually. At least 85 per cent of these people die of heart attacks and strokes, including asymptomatic people who seem perfectly healthy.

These statistics make us wish for a way to effectively predict the probability of heart attack, especially among the asymptomatic middle-aged population. Like an early-detection test for cancer so that the individual could either adopt a lifestyle alteration or appropriate medical intervention to minimize future cardiac risk and over-reliance on medication.

The good news is that such a test actually exists, and it takes only five minutes. Unfortunately, most of us have not even heard about it.

Heart tests: How it all started

Earlier, heart-attack risk assessment was more about mathematical formulae than medical evidence — largely based on the 1959 Framingham risk score study, it was about percentile calculations using individual risk factors such as cholesterol, hypertension, blood glucose, tobacco use, age, genetics and even ethnicity. But there was a rider – the assessment could swing both ways. So, one could have all these risk factors and still not get an attack, and vice versa.

Douglas P Boyd, a former professor of physics at the University of California San Francisco (UCSF), started toying with the idea of capturing the image of the human heart in the late 1970s. Fluoroscopy was already in use to capture the human heart but, due to motion blur caused by heartbeats, the image was not clear enough to show finer details like calcium crystals. After extensive research, Boyd perfected the electron beam computed tomography (EBCT) scanner that could capture the image of the beating heart with precision.

But experts became even more fascinated with the white crystal specks on those images — calcium deposits on plaques. Initially there was no standardised score to interpret the findings. But in 1990 Dr Arthur Agatston, a cardiologist, developed the CAC score (also known as the Agatston score) on the basis of the density of these deposits on the CT scan image.

Coronary calcium and plaque — marker for heart blockage 

“Men starting at age 40-45, women at menopause — earlier if either group has a lot of advanced risk factors (bad family history, Asian-Indian descent, diabetes, familial hyperlipidemia [high cholesterol], etc.),” Dr Matthew Budoff, Professor of Medicine, University of California Los Angeles, Endowed Chair of Preventive Cardiology, Lundquist Institute, California, told Happiest Health when asked who should get their calcium score assessed. “This CAC scan is the mammogram of the heart — if we find early disease, we can treat it early. If we find it late, people die or get bypass surgery.”

Calcium gets deposited along the walls of the arteries wherever there is scarring caused due to the deposition of cholesterol- and lipid-laden plaques because of atherosclerosis. With time, the gooey plaques along with the calcium crystals undergo complex vascular interactions, solidify and even rupture, leading to blood clot and heart attacks. So, calcification in the coronary arteries also means the highest chances of plaque formation that will lead to stenosis (narrowing) of artery and blockage.

“Calcium scoring is recommended in individuals who are asymptomatic and are at high risk for atherosclerotic disease,” Professor Dr Grigorios Korosoglou, chief physician, Department of Cardiology and Angiology, GRN Clinic, Weinheim, Germany, told Happiest Health in an online interaction. “The calcium score helps to reclassify persons who are presumably at low/intermediate risk to high risk. Thus, such patients would profit in this case from early lipid-lowering therapy.”

Dr CN Manjunath, cardiologist and director, Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bengaluru, said calcium deposits in our arteries are seen as a marker for heart blockages associated with atherosclerosis since these spots could identify locations with plaque formation in coronary arteries. “Calcified arteries mean there are high chances of cardiac blockages, especially in those already identified with risk factors like hypertension, diabetes, obesity and genetic history of cardiac complications in their family,” he said. It is also true that not all persons with calcification will have significant blockage.  This can be clarified initially by TMT / Stress Thallium Studies. If these tests are positive then Cathlab Coronary angiogram to be done, but for assessing calcium in the coronary arteries, Cardiac CT is very useful, he added.

Reiterating the role of calcium as an indicator for cardiovascular complications, Dr MA Srilakshmi, cardiologist, St John’s Hospital and Medical College, Bengaluru, said that signs of abnormal coronary calcification in middle-aged people is an indicator of many cardiovascular complications.

“If the calcium score is zero, the chance of a heart attack within the next five years is negligible,” Dr Jayagopal PB, director and interventional cardiologist, Lakshmi Hospital, Palakkad, told Happiest Health. “A score of more than 400 calls for further detailed evaluation. Between 100 and 400 is the grey zone and has to be interpreted in the context of risk factors. An exercise treadmill test is often indicated, and the decision is based on that and symptoms.” A calcium score over 1,000 is considered extremely high.

Reassessing risk and reclassification

A team of researchers from Johns Hopkins University compared heart-attack risk-assessment methods using the traditional risk factors with the coronary calcium score of 7,000 subjects. Their conclusions, published in the December 2013 edition of European Heart Journal, pointed out that 15 per cent of low-risk category people as per the traditional parameters had to be inducted into the high-risk category due to a high CAC score and higher probability of heart attack in the next seven years. The 35 per cent who were being overtreated as high-risk individuals requiring serious medication — including aspirin and statins (cholesterol-lowering drugs) — were reclassified into low-risk category on the basis of their zero CAC scores.

“We showed that by using only the traditional risk factors, we miss a significant percentage of individuals at high risk,” says Dr Michael G Silverman, lead author of the report, in an official media release. “We may also be overtreating a large number of people who can safely avoid lifelong treatment.”

The Mediators of Atherosclerosis in South Asians Living in America (MASALA), a pooled cohort study group at the UCSF, along with a team of expert cardiologists conducted a study on 1,114 individuals to estimate their 10-year cardiac risk factor using traditional methods and CAC scores. The findings published in Elsevier in October 2021 revealed that classifying South Asians with borderline risk for statins intervention could actually not be required and might result in ‘excess’ medication, and further risk assessment with CAC may help to extend better personalised statin allocation in these people.

“Knowing one’s own CAC score can help motivate the person to work on their lifestyle factors,” Dr Alka M Kanaya, Professor of Medicine, UCSF and principal investigator, MASALA study, told Happiest Health. “Having a high CAC score (>100 or >than the average for one’s age/sex) should be a wake-up call to get in better shape, work on diet, and start on preventive medications too.”

Dr Kanaya said that the CAC score along with the atherosclerotic cardiovascular risk estimator approved by the American Heart Association (AHA) and the American College of Cardiology (ACC) could determine the overall risk of developing heart disease in the next decade. She said that those with intermediate risk (7.5 – 20 per cent) with this risk calculator should consider getting the CAC scan. If the CAC score is >100 or higher than the median score for their gender and age, then the person is considered to be at higher risk and should follow their cardiologist’s medical advice.

Scan vs stent vs statins

Among the biggest ironies in medical history would be that Phil Romano, multimillionaire owner of multiple chains of restaurants and fast-food joints serving cholesterol-laden junk food to millions of people, also bankrolled the balloon-expandable heart stent which became the last line in treating people with heart attack. Romano made a fortune selling heart-attack-causing junk food and then went on to make an even bigger fortune selling implantable stents to save people from heart attacks.

Dr Julio Palmaz, the inventor of this heart stent, explains his first meeting with Romano in Patrick Forbes’ 2015 documentary The Widowmaker. “At the end of our meeting, he [Romano] with the thing [the stent] in his hand, he was rolling it around and said, ‘This looks like something I could put in a box and sell for lots of money,’” he says to the camera while describing his pitch meeting with Romano.

The genius of Palmaz’s stent was that it ensured that interventional cardiologists no longer had to fear re-stenosis (that is, arteries collapsing after balloon angioplasty) since the stent would support the artery wall and ensure there is no blockage for blood flow.

“The balloon is used to expand the narrowed artery and a stent is inserted,” Dr Manjunath told Happiest Health. “It (the stent) is like a spring inside a ball pen around the refill. It is on the balloon, and we take it inside the artery and we inflate the balloon. Then the stent sticks to the artery wall. We deflate the balloon and take it out, and the stent remains there and supports the wall.”


The start of the stent route 

The invention of the stent in 1988 revolutionised cardiac-treatment protocols and saved millions of lives across the world. But unfortunately, riding on the stent wave, there was an unprecedented increase in the number of people getting ‘stented’ across the US and in other countries. The situation became so dire that even the FBI had to step in and investigate a section of doctors and hospitals in the US for forcing people to undergo expensive stenting procedure without any valid medical reason.

The stent remained unopposed in cardiac therapy until the popularisation of statins in the late 1980s. In 2007 a major $33.5 million clinical trial – code-named COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) — was conducted in the US. The study proved that there was not much of a difference in the health of people subjected to the overly expensive stents and the comparatively cheaper medical therapy using drugs like statins and lifestyle interventions. However, researchers have also pointed out that many cholesterol-lowering drugs reportedly had side-effects, including higher insulin resistance and blood glucose spikes.

Moonwalk, Clinton and coronary calcium score

Amidst all these upheavals in the cardiac industry until the mid-2000s, the coronary calcium CT scan continued to languish in the shadows. Though the general public remained unaware about it, the CAC test had got enlisted in some of the highest corridors — from the US Oval Office to top government space agencies like NASA.

After 2004, the CAC score shot into limelight when former US president Bill Clinton complained of chest pain, was diagnosed with multiple coronary blockages and had to undergo a quadruple bypass surgery. Clinton used to constantly talk at public events about his “excellent” health and exercise regimes. He had talked about his cardiac health with Dr Budoff and mentioned how he had passed the treadmill, cholesterol and other tests, and only his calcium score was off the charts. Happiest Health independently confirmed about the Clinton incident with Dr Budoff.

Soon after the Clinton episode, the coronary calcium score started getting more traction in the media and political circles. During Donald Trump’s term in the Oval Office, his calcium score exceeding 100 was a matter of public debate and got widely reported.

Meanwhile, NASA was already looking beyond the traditional cardiac-screening protocols to prevent any untoward health scare during its outer-space missions. During the Apollo 15 mission in 1971, lunar module pilot James Irwin had started showing signs of extensive chest pain in the crew module, triggering panic in space and also at the mission command on earth. He had stabilized soon and returned to earth safely, but suffered a massive heart attack a couple of months later.

Though NASA already had a meticulous health-screening process for its mission crew, the incident highlighted that sometimes heart attacks evade the traditional risk parameters.

From 2008 onwards, to prevent astronauts from suffering cardiac events during space missions, space agencies in many countries (including NASA) made it mandatory for all mission crew to also clear CAC scans to become eligible to travel to the stars.

Avoiding unnecessary medication

The global push by a section of cardiologists to get the CAC score included in the list of approved cardiovascular disease screening met with lot of resistance from various quarters, and it took more than two decades until it got approved by the AHA and ACC in 2012.

“As opposed to risk enhancers and screening tools that may be used to identify higher risk patients, CAC testing is now mostly used for identifying lower risk patients among those who would otherwise be candidates for statin therapy but who have a preference to avoid such therapy,” says one of the key points in these guidelines.

It also highlights how the CAC would be beneficial for older individuals between 76 and 80 years of age with an LDL cholesterol level of 70 to 189 mg/dl, in reclassifying those with a CAC score of zero and in avoiding statin therapy.

The calcium CT scan was supposed to be published as an approved screening method in Circulation, the official journal of the AHA in 2004 itself but it was withheld at the last moment and dumped in cold storage — on the grounds that the information was leaked to the Washington Post before the formal publication, leading to breach of the journal’s ‘media embargo’ code.

Why calcium test remains under wraps

In September 2019 Elsevier published a review article on the lack of focus on screening and early detection of cardiovascular diseases (CVDs), especially atherosclerosis. It said that despite cardiovascular diseases killing more people than all cancers combined, the United States spends 20 times more on screening asymptomatic cancer than asymptomatic atherosclerotic CVDs.

Dr Kanaya told Happiest Health that the main reasons for the CAC score not being widely popular for a long time in the US were because it was not included in the health insurance cover of many, a reluctance among a section of cardiologists to prescribe it and lack of adequate media coverage.

“The insurance industry is withholding it from the general population, as they don’t want to pay for it,” Dr Budoff said. “It is widely advocated in guidelines around the world. It is up to the insurance industry, at least in the US, to make it available. They do not like screening tests, as sometimes we find serious disease that needs more treatment. They don’t like mammography either, but legislation forced their hand, and breast cancer awareness is a much bigger movement than heart disease awareness, even though heart disease kills 10 times as many women each year as breast cancer.”

Boyd, the inventor of the coronary calcium scan, in an interview to a YouTube channel in 2018, said that one of the biggest obstacles while trying to promote the scan in the early days came from prominent health-industry players, including pharma companies, since the scan could indicate whether a person actually required medication or surgery.

A section of experts claims the CAC scan involves radiation and could have some side-effects. But most experts say that though radiation exposure is involved in the scan — just like in all health-imaging methods — it is minimal. Of course, care should be taken when the patient is very young.

“[There are] no harmful effects from a calcium score — it is non-invasive (no needles or injections) and only affords minimal radiation (same as a mammogram),” Dr Budoff said.

Dr Korosoglou said the radiation exposure with the calcium score was less than 1mSv (millisievert) and was not a relevant issue usually.

Dr S Shanmugasundaram, cardiologist, Billroth Hospitals, Chennai, told Happiest Health that there was a general reluctance on the part of a section of medical experts in recommending the CAC score and they often preferred the traditional risk assessments. “It has an incremental benefit of risk assessment especially in individuals considered to be in the intermediate risk by traditional methods. It helps in reclassifying the risk status in this group, either up or down in the risk scale.  It is inexpensive, widely available, rapidly done with no significant radiation exposure,” he said. “The CAC score, unlike other risk-assessment tests, need not be taken frequently. Once in 10 years is good enough to predict heart-attack vulnerability in people above the age of 40 with other risk factors, and they can [then] opt for appropriate treatment.”

Dr Shanmugasundaram said special software could be easily installed in many of the modern newer versions of  scanners so as to make it compatible with interpreting the Agatston calcium scores.

Shashi Kumar Shetty, Assistant Professor, Medical Imaging Department, KS Hegde Medical Academy, Mangaluru, said that the newer scanners had incorporated CAC score interpretation. He said only scanners with 64 slice or above would be able to carry out this scan, and added that most modern health facilities were equipped with them.

“Regular coronary calcium score should be mandatorily calculated in every person before conducting a CT angiogram,” said Shetty. “The general norm is that CT angio is not done on those with a calcium score over 400. We don’t inject the contrast dye as there is already high calcification and there could even be the possibility of a complications. Most people have heard about CT angio but very few know about the CAC score.”

Caution needed, say doctors

Even as they confirm the efficacy and accuracy of the coronary calcium CT scan, some medical experts remain apprehensive that if not used judiciously in the case of symptomatic patients — especially those who have already suffered heart attack or have been confirmed to have cardiovascular conditions — then there is no relevance of getting a CAC scan done. Dr Kanaya elaborated this aspect to Happiest Health on the basis of the ACC-approved heart attack risk guidelines, that is, if a person has already survived a heart attack then he need not get his calcium score taken again. People who have also confirmed multiple high cardiac risk factors and conditions can also skip the calcium test.

“If someone has high risk based on these traditional risk factors (>20% with the risk calculator), then there is little added value of the CAC since this person should already be on very aggressive treatment,” Dr Kanaya said. “Similarly, for someone who has already had a heart attack, there is no added value in checking CAC; they should already be on aggressive treatments.”

Dr Jayagopal said since there were possibilities of misinterpretation and misuse, he did not recommend CAC as a routine screening strategy. “All the same, it can provide insights into your risk and thus help in preventive strategies,” he said.

Share Your Experience/Comments

23 Responses

  1. Thank You for your response and interest in our stories and content. Please find our newsletter subscription link on our homepage.

  2. Many years ago when I worked at SIEMENS Healthcare I was actually part of the team developing CT Calcium Scoring application on .NET platform. We had domain training on how Calcium scoring can indicate a patient’s heart health.

  3. Good info
    How to reduce CAC level, Prevent is better than cure.
    Otherwise,it looks more like business.

  4. This article is so insightful. Everyone should get it done. Really appreciate your efforts.??

  5. Very well written article, nice research and enough information for us to understand the details. Like to thank Happiest health & Binoy for throwing light on important health information like this in a consumable manner

  6. It is really useful in cardiac cases or who are at risk of getting it like I’m having familial dyslipidaemia in our family. My mother had CVA and I got my CABG at the age of 41. I wish to know how this CAC test is done and how long does it take ?

  7. Excellent and informative article. This should be a routine and standardized test for anyone who might be at risk. Thank you for bringing attention to it.

    1. Thank You Spencer. Hope you are doing well. Wishing a happy and healthy life to you and family.

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