Dr Siiri Iismaa working in the lab in the Institute's early days

Women in Science - Dr Siiri Iismaa

How one of the Institute’s longest serving staff members is helping progress SCAD research

2 May 2024

Dr Siiri Iismaa, 1997

Dr Siiri Iismaa, 1997

Rewind to 1994. Bill Clinton is President, Disney’s The Lion King is the highest-grossing film, Janet Jackson is top of the pop charts, and the World Wide Web is just a toddler.

It was also the year that Dr Siiri Iismaa started working at the Victor Chang Cardiac Research Institute on Tuesday the 14th of June.

Dr Iismaa says: “It was just myself and one other scientist. We hardly had any equipment, so we had to borrow a lot of it from next door. We shared a Macintosh computer the size of an ATM machine. It’s quite funny to think of the technology back then. If I wanted to get my hands on a scientific journal, I had to make a trip to the library and I’d often have to wait months for the latest issue to arrive on a boat from America.”

More than 10,000 days later and the world is a very different place, but one thing hasn’t changed – Dr lismaa still works for the Institute.

From heart regeneration to biochemical analysis, Dr Iismaa has lost track of the number of research projects she’s worked on. She’s now focused on a disease called Spontaneous Coronary Artery Dissection, or SCAD for short.

Dr Siiri Iismaa in her Victor Chang Cardiac Research Institute laboratory in Sydney

SCAD is a rare but serious condition that results when an inner layer of one of the blood vessels in the heart separates and blood seeps between the artery layers. This expansion of the artery wall slows or blocks blood flow down the artery, causing angina, heart attack, abnormalities in heart rhythm or sudden death.

Women at risk

Dr Iismaa says: “When we first began researching SCAD, I was struck by the fact that around 90 percent of the cases were women and were not your traditional high-risk patients. They were not overweight, or diabetic and were fit. And then, all of a sudden, they presented to the hospital or GP with a heart attack because their coronary arteries had split. A lot of the time they just got sent home without treatment because back then so few medical professionals knew about SCAD.”

The Institute’s team first began investigating SCAD after being contacted by mum of four Pamela Byles, who suffered a SCAD heart attack as she was taking out the laundry.

At the time in 2014, she was told by specialists her SCAD heart attack was 'extremely rare’, ‘a one in a million', 'I’ve never seen this before' and she was 'lucky to be alive'.

Pamela recalls: “I felt a twinge in my chest, almost like a click. Then I felt a sudden intense, extreme pain just to the left of the centre of my chest. This pain radiated down both arms and then I felt a wave of nausea wash over me.

"When I got to the hospital, the nurses told me there was nothing wrong and that I’d be going home shortly. Thankfully they did some tests to double-check.”

A social network

Pamela was determined to find out more about SCAD and worked with the Institute to kick-start the first SCAD patient study in Australia. To find patients she went on Facebook. Bingo. It was as effective as a recruitment drive on a jobs site.

Pamela Byles with fellow SCAD survivors

Pamela Byles with fellow SCAD survivors

“SCAD was unheard of back then,” explains Dr lismaa. “I was really amazed by that Facebook page. To think that you could recruit an entire patient database on a social platform is fascinating. Our whole study grew out of that, and everyone was so willing to participate.”

The study also left Dr lismaa’s desk piled high with DNA samples from SCAD survivors.

“Each recruit was given a small take-home kit to collect cells from inside their mouth and then we isolated DNA from those samples. That gave us enough DNA to search the patient’s entire genetic make-up through whole genome sequencing," recalls Dr lismaa.

It soon became apparent that SCAD was not as rare as once thought and was the cause of 25 percent of all heart attacks in women under the age of 50. Today, it’s also much better diagnosed.

Genetic causes of SCAD

Thanks to DNA testing, the Institute’s team has also made huge headway into understanding the genetic causes of SCAD and have now identified a number of genetic variants associated with SCAD.

The team at the Institute worked with researchers from the UK, France, Denmark, USA and Canada in a collaborative study of 1900 SCAD cases. The study identified that predisposition to SCAD involves variants in at least 16 genes.

Dr lismaa working in the lab

Dr Iismaa says: “In about 10 percent of our cases, we’ve identified a genetic variant in a single gene that we believe predisposes people to SCAD. But for the majority of cases, we think that it’s more a matter of people having particular variants in a large number of genes, which we refer to as having a high polygenic risk. Having more of these particular variants predisposes you to an increased risk of SCAD.”

With so many questions still to be answered, and with SCAD heart attack recurrence rates at around 20-30 percent, SCAD survivors can experience a heavy psychological burden.

To address this, Dr Iismaa and the team are collaborating with researchers from the Australian Centre for Heart Health in Melbourne to develop an online facilitated group support program for survivors of SCAD.

Dr Iismaa says: “Feedback from our participants in the pilot program has been very positive, especially for those early on in their SCAD journey. Our team is working hard to better understand what triggers a SCAD attack, how best to recover from it, and how we may one day prevent it.”

Acknowledgement of Country

The Victor Chang Cardiac Research Institute acknowledges Traditional Owners of Country throughout Australia and recognises the continuing connection to lands, waters and communities. We pay our respect to Aboriginal and Torres Strait Islander cultures; and to Elders past and present.

Victor Chang Cardiac Research Institute - The Home of Heart Research for 30 Years