Prognostic implication of left atrial strain in patients undergoing totally thoracoscopic ablation of atrial fibrillation

Background Atrial fibrillation (AF) is a common form of arrhythmia and associated with poor quality of life. Totally thoracoscopic ablation (TTA) is a novel minimally invasive strategy for symptomatic atrial fibrillation (AF) refractory to other therapy. However, some of patients undergoing TTA are still exposed to a risk of AF recurrence. Purpose The aim of this study is to investigate prognostic factors related with AF recurrence after TTA, and to determine the prognostic implication of left atrial (LA) strain in this population. Methods This was a prospective observational study. Between February 2012 and March 2015, left atrial appendage (LAA) was harvested from patients who underwent TTA in our Medical Center. Degree of LAA fibrosis was expressed as the percentage of area of positive collagen staining in the total area of the image of specimen. All echocardiographic parameters were measured in preoperative echocardiography. The primary outcome was any recurrence of AF detected in 12- lead electrocardiogram or holter monitoring during 5 years of follow-up. Results Out of 150 patients who underwent TTA during the study period, 129 were eligible for analysis with appropriate surgery, LAA specimen, and echocardiographic images. A mean age was 54.4±8.8 years, and 123 patients (95.3%) were male. Twenty four patients (18.6%) had paroxysmal AF and a mean CHA2DS2 VASc score was 1.1±1.2. A median value of peak longitudinal LA strain (reservoir strain) was 15.2% (IQR 12.1–19.2), and the median value of LAA fibrosis was 38.5% (IQR 33.0–44.7). Among clinical and echocardiographic variables, peak longitudinal LA strain (p<0.001) and left ventricular ejection fraction (p=0.044) were significantly associated with degree of LAA fibrosis (Figure). Of 129 patients, 47 (36.4%) experienced recurrent AF during the median 3.9 years of follow-up. In a multivariable Cox regression analysis using clinical, echocardiographic and operative parameters, peak longitudinal LA stain was the only predictor of recurrent AF (adjusted HR 0.89, 95% CI 0.81–0.98, p=0.024; Table). Conclusions Peak longitudinal LA strain was associated with LAA fibrosis, and was a significant predictor of recurrent AF after TTA Funding Acknowledgement Type of funding sources: None.