Early arrhythmia risk stratification: echocardiographic strain insights for non-invasive prediction of atrial conduction abnormalities

Strain echocardiography provides a macroscopic assessment of biomechanical function of the heart. Previous studies demonstrated that atrial strain measurements are promising predictors of atrial tachyarrhythmias, including atrial fibrillation (AF). The onset and perpetuation of AF is facilitated by conduction disorders, which in turn contribute to biomechanical dysfunction. Given this relationship, atrial strain measurements may serve as an ideal noninvasive tool to detect atrial conduction abnormalities and predict atrial tachyarrhythmias.

To investigate the association between atrial biomechanical function and conduction abnormalities, and to identify specific strain markers predictive of conduction abnormalities to support early arrhythmia risk stratification.

Intraoperative high-density epicardial mapping (192 unipolar electrograms) during sinus rhythm was performed in adult patients (N=19) undergoing surgery for coronary artery disease (N=15) or aortic disease (N=4). The unipolar potential voltages, fractionation, conduction velocity (CV), conduction delay (CD) and conduction block (CB) were measured. CD and CB were defined as an inter-electrode conduction time of ≥7ms and ≥12ms respectively. Atrial function was analyzed with speckle tracking echocardiography using Intellispace, Philips software. Atrial strain measurements were performed of the end-diastolic reservoir, conduit and contractile phase of both atria, with subsequent calculations of cycle durations, area under the curve (AUC) and slope of the reservoir strain as well as the contractile strain.

The mean age was 62.9±13.3 years, with a left atrium (LA) and right atrium (RA) area of 17.7±5.7cm² and 17.3±6.3cm². On LA measurements, area and circumference were strongly correlated with increased CD around the pulmonary veins (PV) (ρ=0.72, p<0.01 and ρ=0.69, p<0.01 respectively). Compared to strain measures, a higher LA reservoir strain was associated with an increase in CD around the PV (ρ=0.63, p<0.01), as well as a decrease in CV (ρ=-0.55, p=0.01). A steeper slope preceding the reservoir strain on LA measurements is correlated with more CB and slower CV around the PV (ρ=0.60, p<0.01 and ρ=-0.56, p=0.02 respectively). When examining the contractile slope of the LA, a steeper slope can be found in patients with a higher LA CV (ρ=0.59, p=0.01). A larger AUC was found in patients with more CD and a slower CV around the PV (ρ=0.64, p<0.01 and ρ=-0.52, p=0.03 respectively).

Specific strain measures, including atrial dimensions, reservoir strain, conduit strain, and the slope of contractile strain, may serve as valuable non-invasive predictors of conduction abnormalities. These markers could aid in identifying patients at higher risk for atrial tachyarrhythmias, such as AF, enabling early risk stratification and potentially more targeted, proactive treatment approaches.