A new analysis involving more than 13,000 people has found that changes to blood vessels in the brain that can increase the risk of stroke and dementia are common in people with a range of heart conditions, regardless of whether they have already had a stroke. The new research, published in Neurology®, the medical journal of the American Academy of Neurology, is the most comprehensive systematic review to date of “hidden” brain changes in people with a range of heart conditions. The study’s lead author, Dr. Zien Zhou of the George Institute for Global Health, explained that identifying these changes could play an important role in selecting treatments for these patients.

Changes in Blood Vessels in the Brain Increase the Risk of Stroke and Dementia

Although people with heart disease are two to three times more likely than the general population to have changes in the vasculature of the brain, these are often overlooked because these patients do not routinely undergo brain imaging unless they have suffered a stroke. But this leaves them more susceptible to the risk of cerebral hemorrhage 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.

Changes in blood vessels in the brain that can only be detected by imaging tests, such as silent cerebral infarction (SBI) and cerebral small vessel disease (CSVD), are known to occur more often in older people or those with high blood pressure. Although not sufficient to cause obvious neurological symptoms, they can lead to 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, valvular heart disease, and patent foramen ovale (hole in the heart), researchers at the George Institute conducted a meta-analysis of 221 observational studies conducted between 1988 and were published in 2022. The results showed that in people with heart disease:

• about a third had some form of SBI
• a quarter had lacunae (small cavities where nerve tissue has died after a previous blockage or leak in small arteries)
• two thirds had white matter lesions (damage to the protective layer around the nerve fibers)
• a quarter had signs of asymptomatic microbleeds in brain tissue, and
• more than 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 in people with and without recent stroke, and there were no obvious sex differences in outcomes. Dr. Zhou said the study also confirms that heart disease is a major cause of these changes, which reflect the “frailty” of the brain. Although several potential mechanisms for the association between heart disease and hidden cerebrovascular damage have been demonstrated, both diseases share common risk factors such as aging, hypertension, type 2 diabetes, hyperlipidemia and smoking. It is possible, according to Zhou, that a gradual decline in cardiac output in some heart disease patients affects the amount of blood reaching brain tissue, contributing to vascular changes and cognitive dysfunction in these patients.

Improving Treatment Safety for People With Heart Disease

It is also possible that the hidden brain changes and cognitive dysfunction are a result of tiny blood clots that travel to the brain through the arterial circulation after forming in the heart. Dr. Zhou said more research is needed to investigate the exact causes of these brain changes and the implications for the treatment of these patients. According to the researcher, it is important to know whether performing an additional MRI scan in those eligible for anticoagulation therapy – which is required for most people with heart disease – would be cost-effective in terms of preventing unwanted side effects.

But refining the risks of brain clots and bleeding from anticoagulants and using that information to make the best treatment decision could improve treatment safety for people with heart disease.