Atrial anatomy and function in patients aged 75 years or older with advanced interatrial block. Data from a...

Advanced interatrial block (IAB) is found in about 10% of subjects ≥75 years and is associated with atrial fibrillation and stroke. It is unclear if IAB association with cardiovascular events is a casual or non-causal association.

To determine the association of advanced IAB with left atrial (LA) imaging parameters and cerebral microemboli.

Prospective multicenter study that included 190 subjects ≥75 years without significant structural heart disease, including 83 patients with advanced IAB and 107 controls with normal P-wave (matched by age and cardiovascular risk factors). Electrocardiogram and transthoracic echocardiography were performed in all subjects. Cardiac and brain magnetic resonance imaging (MRI) were done in a exploratory subgroup of 23 and 26 subjects, respectively.

Mean age was 80.9 years old (81.5 in advanced IAB vs. 80.5 in controls, p = 0.14) and 48.9% were females. There were no significant differences between patients with advanced IAB and controls in LA imaging parameters: reservoir strain (22.5 vs. 22.8%, p = 0.88), conduit strain (-12.6 vs. -11.4%, p = 0.41), contraction strain (-13.1 vs. -14.1%, p = 0.59), maximal 3D volume index (29.2 vs. 30.8 ml/m², p = 0.48), ejection fraction (45.7 vs. 43.6%, p = 0.50), fibrosis burden assessed by Late Gadolinium Enhancement (7.4 vs. 8.8% of myocardium, p = 0.67). In a small brain MRI subgroup, patients with advanced IAB showed a numerically higher prevalence of silent brain lesions than controls; however, this difference was not statistically significant (p = 0.25).

When compared to controls with normal P wave, matched by age and cardiovascular risk factors, advanced IAB is not associated with abnormal LA imaging parameters. Within the limitations of this underpowered study, advanced IAB may have a non-causal association with clinical events, although a causal relationship cannot be excluded.