Blood pressure control reduces dementia risk in mid-life patients with atrial fibrillation

Dementia risk in mid-life patients with atrial fibrillation (AF) can be reduced by controlling high blood pressure, according to a study presented today at EHRA 2019, a congress of the European Society of Cardiology (ESC).

Study author Dr. Daehoon Kim said that AF patients in their 50s and 60s can benefit from lowering their systolic blood pressure (SBP) to 120-129 mmHg, as compared to those with continuously high SBP over 140mmHg.

"It was surprising. We all know that AF is associated with higher risk of dementia, but there was no certain way to protect against AF-associated dementia," explained Dr. Kim, a cardiologist at Yonsei University College of Medicine in Seoul, Republic of Korea. "With this study, we found one potential way to help mid-life patients minimise their risk by as much as 15%," he said.

AF patients with hypertension and taking at least one antihypertensive medication at the time of AF diagnosis between 2005-2016 were enrolled in the Korean nationwide cohort study. Among those with uncontrolled SBP over 140mmHg at initial AF diagnosis, the risk of dementia was compared according to their follow-up SBP control status (<120mmHg/120~129mmHg/130~139mmHg/140mmHg) in multivariable Cox models.

Follow-up analysis of SBP and risk of dementia was calculated from the date of follow-up blood pressure measurement to the date of dementia, death, or December 31, 2016 (end of study period), whichever came earliest. The mean follow-up duration was 5.0 years.

AF, the most common sustained cardiac arrhythmia in the general elderly population, increases stroke risk by a factor of four to five times that of the general population. It has also been associated with cognitive impairment and dementia, even in patients without a prior diagnosed stroke.

Previous studies have suggested that hypertension in mid-life increases the risk of dementia in later life, leading it to be included as a probable risk factor in dementia prevention guidelines.2

"However, observational studies that suggested midlife high blood pressure is a risk factor for late-life cognitive impairment and dementia did not assess the effect of blood pressure change over time on dementia risk," Dr. Kim pointed out. "Also, there has been a lack of data about the association of blood pressure control with risk of dementia in patients with AF."

This study found that lowering blood pressure in patients over 70 years old may not have as big of an impact on dementia risk.

"Strict blood pressure control in midlife can help to prevent atrial fibrillation-associated dementia," Dr. Kim asserted. "However, in those who have entered into later life (over 70 years old), blood pressure control might be of little help."

Study authors used the Korean national health insurance service database to measure blood pressure in 196,388 patients over 50 years newly diagnosed with AF, dividing them into age groups 50-59, 60-69, 70-79 and over 80 years old.

Blood pressure control <130mmHG was shown to lower the dementia risk with similar benefits for patients aged 50-59 and 60-69 with initially uncontrolled blood pressure at the time of AF diagnosis.

"Proper anticoagulation and early cardiovascular risk factor modification, including high blood pressure and prevention of hypoglycaemia in diabetes patients, likely play an important role in reducing the risk of atrial fibrillation-associated dementia," Dr. Kim concluded.