According to a study published in the February issue of the Canadian Medical Association Journal, cognitive and functional decline are “important consequences” of atrial fibrillation even in the absence of overt stroke.
Irene Marzona, Population Health Research Institute, McMaster University, Hamilton, Canada, Mario Negri Institute for Pharmacological Research, Milan, Italy, and co-investigators performed a post-hoc analysis of the ONTARGET (Ongoing Telmisartan alone and in combination with Ramipril global endpoint trial) and the TRANSCEND (Telmisartan randomized assessment study in ACE intolerant subjects with cardiovascular disease ) studies.
Their objective, they reported, was to: “determine the prospective association between atrial fibrillation and cognitive decline, loss of independence in activities of daily living and admission to long-term care facilities.”
The primary outcome measures were decreased cognitive function, new dementia, inability to perform activities of daily living independently, and admission to long-term care. Cognitive decline was defined as a decrease of three or more points in the mini mental state examination (MMSE) score between baseline and follow-up, “new dementia” was a new diagnosis of dementia, reported severe cognitive impairment, or an MMSE score of 23 points or fewer during follow-up.
Of 31,506 patients enrolled in the ONTARGET and TRANSCEND studies, 1,106 patients had atrial fibrillation at baseline and a further 2,052 patients were diagnosed with the condition during the follow-up period (a median of 56 months). The percentage of patients with atrial fibrillation, either at baseline or during follow-up, who met the composite outcome measure of a decrease in MMSE score by three points or more, dementia, admission to a long-term care facility, and loss of independence in performing activities of daily living was higher than the percentage of patients without atrial fibrillation (34.2% vs. 26.1%, respectively). After completing a multivariate analysis, Marzona et al found that atrial fibrillation (either at baseline or during follow-up) was associated with an increased risk of cognitive loss (hazard ratio 1.14; 95% confidence interval 1.03–1.26), new dementia (HR 1.30; 95% CI 1.14–1.49), loss of independence in performing activities of daily living (HR 1.35; 95% CI 1.19–1.54), and admission to long-term care facility (HR 1.53; 95% CI 1.31–1.79). Importantly, a subgroup analysis found that the results were consistent for patients with and without stroke. Marzona et al wrote: “Overall, one third of patients with atrial fibrillation had at least one of these outcomes, compared with about one quarter of patients without atrial fibrillation. In comparison, the rates of clinical stroke were much lower (reported in 4.5% of participants).”
Marzona et al claimed that the significant association between atrial fibrillation and cognitive decline in their study may suggest “an increased prevalence and incidence of subclinical cerebrovascular disease” and added that subclinical cerebrovascular disease, in particular periventricular white matter disease, was associated with cognitive and functional decline in previous studies. They wrote: “Our findings highlight the need to include cognitive and functional measures in clinical trials of patients with atrial fibrillation.” Marzona told Cardiac Rhythm News: “Physicians should be alert to the possibility of increased risk of cognitive and functional decline in patients affected by Atrial Fibrillation. The already validated scales (such as the MMSE that was administered during ONTARGET and TRANSCEND) are useful tools to detect cognitive decline, but it is also the prompt detection of changes in the patient’s usual daily activities that give physicians important information on their functional status.”