Cathriona Muldoon was at a big family celebration for her parents’ 50th wedding anniversary in June 2019 when she suddenly began to feel unwell. “My heart was racing and I started to get sick,” says the 53-year-old. The general manager at the hotel called an ambulance. When the paramedics arrived they gave me three shocks [to stabilise her heart beat] and brought me to hospital for tests.”
At University Hospital Galway, Cathriona was given various tests, including an electrocardiogram (ECG) and echocardiogram (cardiac ultrasound) but no abnormalities showed up. “As it happens I had been going to the cardiology department for the two years previously because I felt breathless when climbing the stairs. But nothing had shown up there either,” she says.
A follow-up cardiac MRI showed scarring (fibrosis) on her heart, but initial genetic testing at the family heart screening clinic at the Mater University Hospital gave her the all clear. However, due to her cardiac arrest Cathriona was fitted with an implantable cardiac defibrillator and prescribed beta-blockers to slow down her heart rate. “I got tired sometimes, but I mainly just got on with my life.”
However, in May 2020, Cathriona’s 44-year-old sister, Sinéad, died in hospital following a cardiac arrest. Her sister’s autopsy showed similar scarring on her heart to that shown on Cathriona’s MRI scan. “I contacted the family screening clinic at the Mater and explained what happened. The clinic then did deeper genetic testing on blood samples from myself and my sister which found we both had the Lamin gene, which causes heart scarring and arrhythmia.” (Arrhythmia is an abnormality which causes the heart to beat too slowly, too quickly or irregularly.)
Follow-up genetic testing on her parents resulted in the discovery that her father, Tony Morris, had the faulty gene. Further testing of his siblings and the next two generations revealed that Cathriona’s two brothers, two of her three children and some other nieces and nephews also had the gene. “My father, who is now 87, has never had a cardiac arrest, although he is on a daily beta-blocker tablet. My two brothers have had implantable defibrillators put in. My eldest daughter will have one put in soon and the doctors will continue to monitor the younger family members,” says Cathriona.
She says she has come to terms with having a genetic heart condition. “For the first two years, I didn’t like to talk about it. But now I’m grateful to be alive. I’ve changed [my attitude] since my cardiac arrest – I don’t worry about the small stuff any more and I’ve realised that the most important gift that I can give anyone is time. I live by that now.”
Cathriona adds that her mother Maisie’s way of coping with the death of her daughter, Sinéad is to think she didn’t die in vain because she has saved all these other family members.
Cathriona also decided to go public about her experience in the hope she can save other people’s lives. “I tried to find other people with the Lamin gene, and I know not everyone wants to talk about these things. But there is nothing to be ashamed about. If I can save lives by speaking out I’m happy to do so.”
Prof Joe Galvin, consultant cardiologist at the Mater hospital, runs the cardiac genetic testing at the hospital. “We mainly see the family members affected by the sudden cardiac death of a young person so that we can look for a genetic cause,” he says.
There are three principal groups of heart conditions potentially caused by a single inherited gene abnormality which can be treated once discovered. These include diseases of the heart muscle called cardiomyopathy. “Hypertrophic cardiomyopathy is when the walls of the heart become too thickened; dilated cardiomyopathy is when the pumping function reduces and people feel shortness of breath and arrhythmogenic cardiomyopathy causes a life-threatening cardiac arrhythmia due to scarring of the heart muscle,” explains Prof Galvin.
The second group of heart conditions with a potential genetic origin is those which cause abnormalities of the heart’s electrical system. These include Long QT syndrome, which can result in sudden cardiac death due to a fast chaotic heart rhythm.
The third group of heart conditions with a potential genetic origin is those which result in the weakening of the walls of the aorta (the main blood vessel into which the heart ejects blood) causing it to bulge and potentially rupture.
However, in spite of increasing knowledge about the genetic origins of cardiac problems not all sudden adult deaths result in family members being able to detect a genetic cause for the early and unexpected death of their loved one. “If the autopsy shows clear evidence of cardiomyopathy and we can go on to analyse the blood samples, we can detect a genetic origin in between 10-15 per cent of cases with cardiac testing (ECG, cardiac ultrasound, treadmill exercise testing) and about 10-15 per cent with genetic testing,” says Prof Galvin.
Family members must, however, give permission for genetic testing of the blood of the deceased family member before the geneticists at the Mater hospital can do deep gene testing to see if conditions are inherited or not.
Prof Galvin believes that more genetic testing of young people who died suddenly can help save more lives. “If we find a lethal gene we must be able to share this information with other family members. People who come for genetic testing sign a consent form to agree to share the information with other family members.”
The cardiology department at the Mater hospital is currently working with the Centre for Cardiac Risk in the Young (CRY) at Tallaght University Hospital and paediatric cardiologists at Children’s Health Ireland at Crumlin to form the Irish Inherited Cardiac Conditions Network. “When we have a confidential registry of families with inherited cardiac conditions we will be able to know more about which genes are more common and work together in the future to access new gene therapies for more patients,” says Prof Galvin.
The Mater hospital, which recently became the first hospital in Ireland to do its own cardiac genetic testing of patients’ blood samples (rather than sending them abroad for genetic testing), offers gene sequencing for patients referred to CRY and the Mater hospital family heart screening. Patients currently wait about six months for such screening.
[ Dillon Quirke: The hurler’s sudden death, grieving family and lifesaving legacyOpens in new window ]
Meanwhile, the Dylan Quirke Foundation, which was set up following the sudden death of 24-year-old Tipperary hurler Dylan Quirke, continues its work to provide free cardiac screening for 12-18 year olds through sports clubs throughout Ireland.
Research has shown that cardiac screening can significantly reduce the incidence of sudden adult death syndrome in young adults. The European Society of Cardiology and the International Olympic Committee recommend cardiac screening every two years for people partaking in competitive sport.
- Sign up for push alerts and have the best news, analysis and comment delivered directly to your phone
- Join The Irish Times on WhatsApp and stay up to date
- Listen to our Inside Politics podcast for the best political chat and analysis
