Why do people with mental illness have triple the risk of a sudden cardiac arrest compared with people without mental illness? This is the question that caught Dr. Carlo Alberto Barcella’s attention when searching for a PhD topic at Gentofte Hospital in Denmark, close to Copenhagen.
“Once I learned this, I thought ‘OK, well it’s probably a good idea to see if there’s any differences in survival after cardiac arrest in these people’,” said Dr. Barcella, originally from northern Italy and now visiting CHÉOS as a postdoctoral fellow, supervised by CHÉOS Program Head of Cardiovascular Health Dr. Karin Humphries and Scientist Dr. Christopher Fordyce.
Cardiac arrest is when the heart suddenly stops beating and is primarily the result of cardiovascular disease (CVD). The majority of cardiac arrests occur in an out-of-hospital setting. People living with mental illness have higher rates of CVD than people without mental illness, and CVD is the leading cause of premature death in this group. Importantly, this population represents a significant portion of society. “In Denmark, it’s estimated that one in three people will receive treatment for mental illness during their lifetime,” said Dr. Barcella. In Canada, by age 40, about half of the population will have or have had a mental illness, which can range from schizophrenia to anxiety to depression.
To understand more about cardiac arrest in people with mental illness in Denmark, Dr. Barcella, who is training to be a cardiologist, set out to answer three questions during his PhD: (1) Are people with mental illness in Denmark at increased risk of having and dying from cardiac arrest?; (2) Are the characteristics and circumstances of cardiac arrest different for people with mental illness?; and (3) Once they reach the hospital, are people with mental illness treated differently after a cardiac arrest compared to people without mental illness?
Using linked, nation-wide registries that connect multiple data sources, the answer he found was an unequivocal ‘yes’ for all three questions.
Inequality throughout the chain of survival after cardiac arrest
Dr. Barcella found that Danes with mental illness had less than half the chance of survival 30 days after an out-of-hospital cardiac arrest compared with people without mental illness. He also found that, although survival rates after cardiac arrest markedly improved in people without mental illness over the previous 10 years, there was no parallel improvement in people with mental illness.
People with mental illness were also more likely to have a cardiac arrest under circumstances that made survival less likely. “We found a higher likelihood of people with mental illness having a cardiac arrest alone,” he said.
But for cardiac arrests that did occur in the presence of a bystander, so-called witnessed arrests, people with mental illness were still less likely to receive CPR from bystanders, a finding that Dr. Barcella believes to be a result of stigma and discrimination.
Sadly, the unequal treatment does not stop there. Dr. Barcella found that once they arrive at the hospital, people with mental illness in Denmark do not receive the same level of treatment as those without mental illness. Specifically, they are less likely to receive coronary angiography, which is used to understand whether the arrest was caused by a heart attack and therefore is treatable by unblocking clogged arteries. But, he said, people with mental illness were less likely to survive regardless of which procedures they received.
Importantly, in all of Dr. Barcella’s studies, mental illness was not treated as monolith. Where possible, results were stratified by type of mental illness or severity of illness in order to get a better sense of the results.
“Pooling everything together can give us an estimate but, for example, cardiac arrest risk is much higher in schizophrenia or bipolar disorder compared with anxiety,” he said. “We need to separate out these groups in order to understand more.”
Why such differences? Replicating analyses in a comparable setting
By nature, cardiac arrest is sudden, unpredictable, and deadly, making studies to understand it very difficult. That’s why using linked data registries, which provide a wide range of information on factors like previous hospitalizations and medication use, are vital in this area of research.
Both Denmark and B.C. have cardiac arrest registries that allow these types of analyses, while also sharing many similarities, like population size and a public health care system. Dr. Barcella explained that this provides a unique possibility to compare strategies for the prevention, treatment, and management of out-of-hospital cardiac arrest between two different countries on two different continents.
“Running a clinical trial in cardiac arrest is very challenging, but if we have similar results in two different, independent registries, then we can have more confidence in the findings,” he said.
In collaboration with Drs. Fordyce and Humphries, and statistician Dr. Meijiao Guan, Dr. Barcella aims to replicate his PhD research using data from B.C. The analyses will follow a similar approach to his PhD questions, with an additional question about the effects of antipsychotic and antidepressant drugs on cardiac arrest risk, something he has recently pursued using Danish data.
“We know that antipsychotics increase cardiovascular risk,” said Dr. Barcella. “For antidepressants, our results suggest that only a few specific medications increase risk. These drugs can cause changes in the electrical system of the heart, increasing the risk of cardiac arrest.”
Dr. Barcella expects that the results in B.C. will mirror those from Denmark, given the similarities between the regions. Furthermore, the combination of these projects will allow for a better understanding of the underlying factors and inform efforts to address the inequalities.
“There is room for improvement in every link in the chain of survival for patients with mental illness,” he said. These improvements range from improving CPR education and reducing stigma, to improving collaboration between psychiatrists and cardiologists to understand and anticipate risk in people who take medications related to mental illness.
During his fellowship, Dr. Barcella hopes to forge a lasting collaboration with researchers at CHÉOS and around the province in order to encourage future complimentary studies and data sharing between B.C. and Denmark.