A new analysis involving more than 13,000 people has found that changes in the brain´s blood vessels, which can raise the risk of stroke and dementia, are common among those with various heart conditions, even if they haven’t had a stroke.
The study, published in Neurology, is the most comprehensive systematic review to date on "hidden" brain changes in people with heart disease. Researchers systematically searched databases like Medline, Embase, and Cochrane Library for hospital or community studies reporting silent brain infarcts (SBI) and cerebral small vessel disease (CSVD) in individuals with heart disease.
Data was extracted from eligible studies, focusing on subtypes of silent brain infarcts (primary) and specific small vessel disease. A meta-analysis of 221 observational studies was conducted, providing summarized prevalence data with 95% confidence intervals (CI). Random-effects models were used to compare individuals with heart disease to those without, assessing the presence of these brain changes.
Key findings included:
- In those with atrial fibrillation (AF), the prevalence of silent brain infarcts (SBI) was 36%, lacunar infarcts (small brain cavities due to tissue death) were present in 25%, and white matter lesions (damage to the protective sheath around nerve fibers) were seen in 62%. Additionally, 27% had microbleeds (small brain hemorrhages).
- The prevalence of silent brain changes was similar between those with and without recent stroke, except for individuals with a patent foramen ovale (PFO), where the prevalence of SBI was lower at 21%.
The study highlighted a high prevalence of SBI and CSVD in people with heart disease, which is consistent across those with and without recent stroke. Age and hypertension were associated with more severe brain changes. No significant difference in the prevalence of microbleeds was found between heart disease patients and controls, but a higher prevalence of SBI and white matter lesions was observed in heart disease patients.
Implications and Future Directions
Dr. Zien Zhou, lead author from The George Institute for Global Health, emphasized the importance of identifying these changes, as they could influence treatment decisions for patients with heart disease. He noted that brain imaging is often not routinely conducted unless a stroke occurs, even though people with heart conditions are two to three times more likely to have brain vascular changes. These changes, such as SBI and CSVD, can increase the risk of stroke and dementia, even without causing immediate neurological symptoms.
The study found that about one-third of people with heart disease had silent brain infarcts, a quarter had lacunar infarcts, two-thirds had white matter lesions, and a quarter had microbleeds. Brain atrophy was also common in over half of the cases. These findings were consistent across various heart diseases, including atrial fibrillation, coronary artery disease, heart failure, and valvular heart disease.
Dr. Zhou explained that heart disease and brain changes share common risk factors, such as aging, hypertension, diabetes, high cholesterol, and smoking. Reduced blood flow to the brain in some heart disease patients could contribute to vascular changes and cognitive decline. Small blood clots traveling to the brain from the heart may also play a role.
Further research is needed to explore the exact causes of these brain changes and their implications for managing heart disease patients. Dr. Zhou suggested that performing additional brain imaging, like MRI, for those undergoing anticoagulant therapy could help prevent adverse side effects by refining treatment options. This could lead to safer and more personalized treatment for heart disease patients.
