Brain stroke
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Brain blood vessel damage that increases the risk of stroke and dementia is common in people with a range of heart conditions, regardless of whether they have experienced a stroke, a new study shows. The team’s findings could help in choosing appropriate treatments for these patients, said lead author Zien Zhou, from The George Institute for Global Health. He adds that the study confirmed that heart disease is one of the main causes of brain “frailty.”

The researchers say their study, published this week in Neurology, is the most comprehensive systematic review of “hidden” brain changes in people with a range of heart conditions to date. This study, which was a meta analysis, included over 13,000 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…these patients don’t routinely undergo brain imaging unless they have suffered a stroke,” Zhou said.

“But it [heart disease] can make them more susceptible to the risk of brain bleeds from medications commonly used to treat or prevent blood clots—intracranial hemorrhage is a life-threatening complication with no proven treatment and a survival rate of less than 50 percent,” he added.

Only brain imaging can detect changes to blood vessels in the brain such as silent brain infarction and cerebral small vessel disease. These conditions are known to occur more commonly in older people or those who have hypertension. While not sufficient to cause obvious neurological symptoms, such events can cause subtle neurological deficits and increase the longer-term risk of stroke or dementia.

To determine the prevalence of these hidden or covert cerebrovascular changes in adults with atrial fibrillation, coronary artery disease, heart failure or cardiomyopathy, heart valve disease, and patent foramen ovale (a hole in the heart), George Institute researchers conducted a meta-analysis of 221 observational studies published between 1988 and 2022.

The findings showed that in people with heart disease:

  • Approximately one third had any form of silent brain infarction
  • 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 fibers)
  • 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 prevalence of these brain changes was generally the same between those with and without a recent stroke and there were no apparent sex differences in the results.

“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 aging, hypertension, type 2 diabetes, hyperlipidaemia, and smoking,” Zhou said.

“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.”

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