Four-dimensional left atrial strain in a murine model of reversible pressure overload

Abstract

Introduction: Left atrial (LA) strain is emerging as a valuable metric for assessing heart failure progression and treatment efficacy. However, the complex geometry and contractile patterns of the LA complicate the evaluation of global and regional function specifically during pressure overload and recovery. Methods: We use advanced four-dimensional ultrasound (4DUS) imaging (Vevo 3100, VisualSonics) and develop novel analytical techniques to evaluate the progression of LA function during pressure overload and recovery. A cohort of mice (n=8) underwent 4DUS imaging to assess LA and left ventricular (LV) function at baseline, 3 weeks post-transverse aortic constriction (TAC), and 1 and 4 weeks post-minimally invasive aortic debanding (deTAC) (Figure 1). Results: LV ejection fraction (EF) significantly decreased 3-weeks post-TAC (p=0.0008) before gradually returning to baseline levels 4-weeks post-deTAC. LA max volume was 11.8 ± 0.8μL at baseline and increased to 30.4 ± 9.4μL 3-weeks post-TAC (p=0.0024) before returning to baseline levels 1-week post-deTAC. Global circumferential strain dropped from 27.7 ± 2.9% at baseline to 8.3 ± 1.0% at 3 weeks post-TAC and improved to 20.7 ± 1.2% by 4 weeks post-deTAC. Significant differences were observed at each time point (Figure 2 A-C). Regional strain analysis revealed superior LA strain differences at baseline, 1 week, and 4 weeks post-deTAC (Figure 2 D-E). Global longitudinal strain decreased (from 24.8 ± 3.6% at baseline to 10.2 ± 3.7% post-TAC, p<0.0001) and partially recovered to 18.9 ± 3.5% at 4 weeks post-deTAC (p=0.0073 vs. baseline). Regional differences were evident in posterior LA strain post-TAC and 4 weeks post-deTAC. Conclusion: Advanced 4DUS imaging and strain analysis techniques enable quantification of global LA function and provide detailed segmental mapping to track the dynamics of LA reverse remodeling. This approach offers a valuable tool for monitoring therapeutic efficacy and optimizing patient management strategies in heart failure or aortic stenosis.