A recent investigation involving more than 13,000 individuals has uncovered alterations to cerebral blood vessels that heighten the likelihood of stroke and dementia in those with various cardiac ailments, irrespective of prior stroke occurrence.
The latest study, released today in Neurology®, the medical publication of the American Academy of Neurology, stands as the most exhaustive systematic assessment of 'latent' brain modifications in individuals with diverse heart conditions thus far.
Principal investigator Dr. Zien Zhou from The George Institute for Global Health emphasized the significance of detecting these changes, suggesting their potential in guiding treatment decisions for such patients.
“Although people with heart disease are two to three times more likely than the general population to have changes in their brain’s vascular system, they’re often overlooked, because these patients don’t routinely undergo brain imaging unless they have suffered a stroke,” he said.
“But it can make them more susceptible to the risk of brain bleeds from medications commonly used to treat or prevent blood clots – intracranial haemorrhage is a life-threatening complication with no proven treatment and a survival rate of less than 50 percent.”
Modifications to cerebral blood vessels, detectable solely through brain imaging techniques such as silent brain infarction (SBI) and cerebral small vessel disease (CSVD), are recognized to be more frequent among elderly individuals or those afflicted with hypertension. While not adequate to induce noticeable neurological symptoms, they can precipitate subtle neurological impairments and heighten the long-term susceptibility to stroke or dementia.
In order to ascertain the prevalence of these concealed or surreptitious cerebrovascular alterations in adults grappling with atrial fibrillation, coronary artery disease, heart failure or cardiomyopathy, heart valve disorders, and patent foramen ovale (a cardiac aperture), researchers at the George Institute conducted a meta-analysis of 221 observational investigations spanning from 1988 to 2022.
The findings showed that in people with heart disease:
* approximately one third had any form of SBI
* a quarter had lacune (small cavities where neural tissue has died after a previous blockage or
leakage from small arteries)
* two-thirds had white matter lesions (damage to the protective coating around nerve fibres)
* a quarter had evidence of asymptomatic microbleeds in the brain tissue, and
* over one half had brain atrophy (a shrinking of the brain due to loss of neurons or connections
between neurons).
The occurrence of these cerebral alterations remained largely consistent regardless of recent stroke history, with no evident gender variations observed in the findings.
Dr. Zhou remarked that the research also validated heart disease as a primary contributor to these alterations, indicative of cerebral 'fragility'.
“While several potential mechanisms of the association between heart disease and hidden cerebrovascular injury have been proposed, the two conditions share common risk factors such as ageing, hypertension, type 2 diabetes, hyperlipidaemia, and smoking,” said Dr Zhou.
“It’s possible that a gradual decline in cardiac output in some patients with heart disease might affect how much blood is reaching the brain tissue, contributing to vascular changes and cognitive dysfunction in these patients,” he added.
“It’s also possible that hidden brain changes and cognitive dysfunction are a consequence of tiny blood clots traveling to the brain through the arterial circulation after forming in the heart.”
Dr Zhou said that more research was needed to look at the exact causes of these brain changes and the implications for managing these patients.
“We need to know whether performing an additional MRI in those considered for anticoagulation therapy - which is required for most people with heart disease - would be cost-effective in terms of preventing unwanted side effects,” he said.
“But refining the risks of brain clots and bleeds from anticoagulants and using this information to make the best treatment choice could improve treatment safety for people with heart disease.”
