Abstract
Background
Atrial performance assessed by strain imaging is used as a surrogate for left atrial (LA) structural remodelling. Presence of low voltage zones (LVZs) detected by three-dimensional electroanatomical mapping in patients with atrial fibrillation (AF) denotes more expressed extrapulmonary substrate potentially leading to worse outcomes following pulmonary vein isolation (PVI) for the treatment of AF.
Purpose
The current study aims to investigate the association between strain imaging parameters from echocardiography and the presence and extent of LVZs derived from LA electroanatomical mapping in patients undergoing AF ablation.
Methods
Seventy-eight patients (58 males, 74%) aged 59±9.48 years undergoing PVI for paroxysmal (35 patients, 49%) or persistent AF were prospectively studied. Preprocedural echocardiography included LA strain imaging assessing global LA strain (LAS) and regional strain of the basolateral region (RSLB). During the procedure, LA electroanatomical mapping during paced atrial rhythm was performed in all patients obtaining a LA voltage map. All LA maps were analysed offline using a custom-made software calculating the zone of low bipolar voltage <0.5 mV (LVZ<0.5mV) and the total LA endocardial area excluding pulmonary veins antra. LVZ<0.5mv was expressed as an absolute value and as percentage of the whole LA area.
Results
Patients aged more than 65 years (N=21, 27%) demonstrated a larger area of LVZ<0.5mV: 25.5±17.8 cm2 vs. 9.4±10.6 cm2 in those younger than 65 years, P=0.001. This corresponded to a higher proportion of the LA area demonstrating LVZ<0.5mV in patients older than 65 years: 22.6±14.6% vs. 8.9±11.8% in those younger than 65 years, P<0.0001. Twenty-nine of 78 patients (37.1%) had preprocedural LAS<20% and 23 (29.5%) demonstrated RSLB of <21%. Patients with LAS <20% had a higher total LVZ<0.5mV: 20.3±16.6 cm2 vs. 9.8±12.1 cm2 in patients with LAS≥20% at baseline, P=0.004. This equaled to 17.7±15.6% vs. 9.5±11.9% of total LA area, respectively (P=0.011). Patients with RSLB<21% also demonstrated larger areas of LVZ<0.5mV in the LA: 21.6±17.9 cm2 vs. 10.39±11.83 cm2 in the patients with RSLB ≥21%, P=0.012. Expressed as a proportion of the whole LA area the difference remained significant: 18.8±17.1% vs. 9.9±11.6%, respectively P=0.01.
Conclusion
Older age and impaired LA performance assessed by LA strain imaging are associated with larger areas of LVZ<0.5mV possibly reflecting more expressed LA fibrotic changes in patients with paroxysmal and persistent AF. These findings might serve in the preprocedural selection of the patients undergoing catheter ablation of AF.
FUNDunding Acknowledgement
Type of funding sources: Other. Main funding source(s): Bulgarian Society of Cardiology
Roles of the Left Atrial Roof and Pulmonary Veins in the Anatomic Substrate for Persistent Atrial Fibrillation and Ablation in a Canine Model
