In June 2019, while attending her parents’ golden wedding anniversary celebration, Cathriona Muldoon, aged 53, experienced a sudden bout of illness. She recounted a racing heartbeat followed by nausea. The hotel’s general manager promptly called for medical aid, and upon their arrival, the paramedics had to administer three shocks to stabilise her heart before transporting her to the hospital for further examinations.
Following these events, Cathriona underwent several medical procedures, including an electrocardiogram (ECG) and an echocardiogram (cardiac ultrasound) at University Hospital Galway. Still, there were no detectable issues. Cathriona had previously been undergoing cardiology tests for breathlessness during stair-climbing but the tests turned up no abnormalities either.
Further examination through a cardiac MRI indicated scarring, also known as fibrosis, on her heart. The Mater University Hospital’s family heart screening clinic carried out preliminary genetic tests that did not find any issues. Still, she had an implantable cardiac defibrillator fitted, and beta-blockers prescribed for her cardiac arrest. Cathriona admitted to bouts of tiredness, adjusting to her conditions and carrying on with life as usual, for the most part.
However, in May of the following year, her younger sister Sinéad, aged 44, tragically passed away in hospital due to cardiac arrest. An autopsy of Sinéad revealed comparable scarring on her heart, akin to the scarring on Cathriona’s heart seen in her MRI scan. This led Cathriona to reach out to the family screening clinic at the Mater. Subsequently, more in-depth genetic testing was performed on blood samples from Cathriona and her late sister, revealing they both carried the Lamin gene. This gene is associated with heart scarring and arrhythmias, conditions presenting as irregular heartbeat speed or pattern.
Genetic tests on Cathriona’s parents led to the detection of a defective gene in her father, Tony Morris. Upon further examination of Tony’s siblings and the subsequent two generations, it was found that her two brothers, two out of her three children as well as some nieces and nephews carry the same gene. Tony, now 87, has never experienced a cardiac arrest but is on daily dose of beta-blocker tablet. Implanted defibrillators have been provided for Cathriona’s two brothers and her eldest daughter is soon to have one. The health of the younger family members will be continually observed by the doctors, according to Cathriona.
Having accepted her genetic heart condition, Cathriona confesses that her views have transformed since her cardiac arrest. She stresses the importance of time as a vital gift, and doesn’t sweat the small stuff anymore.
Cathriona then comments that her mother Maisie has used the death of her another daughter, Sinead, as motivation for saving the lives of other family members, believing that Sinead’s death wasn’t in vain.
To help others, Cathriona has chosen to freely share her experience. She wanted to connect with those carrying the Lamin gene and encourage them to not feel embarrassed about it, and firmly believes that if her story can save lives, she is more than happy to disclose it.
Prof Joe Galvin, a consultant cardiologist at the Mater hospital and head of the cardiac genetic testing there, explains that their main job is to look for a genetic cause amongst the relatives affected by the sudden cardiac death of a young person.
He briefs that three major groups of heart conditions possibly caused by a single genetic anomaly can be treated upon detection. These involve diseases of the heart muscle named cardiomyopathy. He describes hypertrophic cardiomyopathy as thickening of the heart walls, dilated cardiomyopathy as reduction of the pumping function leading to breathlessness, and arrhythmogenic cardiomyopathy as causing life-threatening cardiac arrhythmia due to the scarring of the heart muscle.
The second category of potentially genetically induced heart conditions is those that lead to irregularities in the heart’s electrical system. Conditions such as Long QT syndrome fall under this category, and they could result in sudden and fatal heart rhythm abnormalities.
The third category of potentially genetically based heart issues results in the weakening of the aorta’s walls – the main conduit carrying the heart’s discharged blood. This could cause it to swell and possibly rupture.
Despite the increased understanding of genetic influences on heart issues, not all sudden instances of adult death enable relatives to uncover a genetic reason for their sudden and unexpected bereavement. “Upon clear autopsy evidence of cardiomyopathy and the follow-up analysis of the blood samples, we can identify a genetic foundation in 10-15 per cent of the instances via cardiac testing (ECG, cardiac ultrasound, treadmill exercise testing) and roughly 10-15 per cent through genetic testing,” shares Prof Galvin.
However, relatives of the deceased must give their consent for the genetic testing of the deceased’s blood before the genetic experts at Mater hospital can conduct an in-depth gene test to determine the possible inheritance of conditions.
Professor Galvin holds the belief that increased genetic testing on sudden death cases amongst young people could aid in saving more lives. “On discovering a lethal gene, it’s crucial that we are able to disclose this information with other relatives. Those who undergo genetic testing sign a consent form to agree to divulge the information with other members of the family.”
In collaboration with the Centre for Cardiac Risk in the Young (CRY) at Tallaght University Hospital and paediatric cardiologists at Children’s Health Ireland at Crumlin, the cardiology department at Mater hospital is setting up the Irish Inherited Cardiac Conditions Network. “Once we establish a confidential registry of families with inherited cardiac conditions, we can better understand which genes are more prevalent and collaborate on future gene therapies for a larger patient base,” says Prof Galvin.
Recently, Mater hospital became the first in Ireland to conduct its own cardiac genetic testing of patient blood samples, instead of sending the samples overseas for testing. The hospital provides gene sequencing for patients referred to CRY and the Mater hospital family heart screening, and currently, patients have to wait around six months for this screening.
The Dylan Quirke Foundation, established in the wake of the untimely demise of Dylan Quirke, a 24-year-old hurler from Tipperary, persists in its mission to offer cost-free heart screenings for youngsters aged 12 to 18 via sports organisations across Ireland. Investigations have indicated that these heart screenings can significantly lower the rate of sudden adult death syndrome amongst young adults. Consequently, both the European Society of Cardiology and the International Olympic Committee advocate for such screenings biennially for those participating in competitive sports.