1354841 - Left Atrial and Ventricular Strain and Extracellular Volume Fraction in Patient with Paroxysmal and Persistent Atrial Fibrillation

Atrial fibrillation (AF) is a progressive disease that starts with structural and functional changes in the left atrium (LA) evolving from paroxysmal (PAF) toward sustained forms (PeAF), and leads to left ventricular (LV) diastolic dysfunction¹. CMR provides comprehensive assessment of LA/ LV volume and function by cine CMR, LV tissue characterization by LGE CMR and T1 mapping, and LV/ LA strain by feature tracking of cine CMR images. LV extracellular volume fraction (ECV) is the imaging biomarkers of LV diastolic function². Recently, LA volume and function has been extensively studied in patients with PAF³. However, the difference of those LA parameters and ECV between PAF and PeAF still remains unclear. Further, the association between ECV and LA volume and function in patients with AF was not fully studied. The purposes of this study were to compare CMR parameters including LA/LV volume and function and ECV between PeAF and PAF post catheter ablation, and to evaluate the relationship between ECV and CMR parameters in patients with AF.

Methods:

Forty-one patients with AF (25 PeAF and 16 PAF) who underwent CMR study including cine CMR, LGE CMR, and pre- and post-contrast T1 mapping within a week after restoration of sinus rhythm by catheter ablation were studied. Exclusion criteria included myocardial infarction, HCM, DCM, cardiac sarcoidosis, congenital heart disease and valvular disease. LA/LV volume and function and ECV were determined by cine CMR and T1 mapping, respectively. LA reservoir, conduit, contractile strains (εR, εCD, εCT, respectively) and LV global longitudinal, radial and circumferential strains (GLS, GRS, GCS, respectively) were determined by feature tracking.

Results: Patients with PeAF as compared with PAF had significantly impaired LV EF (56.6±7.4% vs. 64.3±6.9%, p=0.001), LA total EF (28.8±7.2% vs. 39.5±9.8%, p< 0.001), active EF (7.9±4.5% vs. 19.1±6.4%, p< 0.0001), εR (7.4±1.9% vs. 9.8±2.3%, p< 0.001), εCT (1.9±0.9% vs. 3.8±1.9%, p< 0.0001) and LV GLS (-13.4±2.4 vs. -15.0±2.4, p=0.04). ECV in patients with PeAF (29.6±3.2%) were significantly higher than that in patients with PAF (27.6±2.8%, p=0.049) (Table 1). In patients with AF, univariate linear regression analyses showed that ECV was significantly correlated with LV ESVI (r=0.33, p=0.03), εR (r=-0.38, p=0.01), and εCD (r=-0.43, p=0.005) (Figure 1). Stepwise multivariate analysis, including LV ESVI, εR and εCD as variables, revealed εCD as the only independent predictor of ECV (β=-0.43, p=0.005).

Conclusion:

Patients with PeAF had impaired LA reservoir and contractile function, impaired LV GLS and increased ECV as compared with those with PAF. LA conduit strain independently predicted increase of ECV in patients with AF. These findings suggest that patients with PeAF suffer from more progressive LA functional remodeling and LV diastolic dysfunction than those with PAF, and that CMR LA strain analysis enables the prediction of the degree of LV diastolic dysfunction in patients with AF.