Abstract Body (Do not enter title and authors here): BACKGROUND:
Arteriovenous fistula (AVF) remains the preferred method of vascular access in patients requiring long-term maintenance hemodialysis for end stage renal disease (ESRD). However, the AVF creates an acute left-to-right shunt, with the potential to cause high output heart failure.

RESEARCH QUESTIONS:
In patients with ESRD and AVF placement:
1) What is the effect of AVF on left atrial (LA) anatomy and function in patients with atrial fibrillation/atrial flutter (AF)?
2) What are the longitudinal effects of AVF placement on prevalence of AF?

METHODS:
We retrospectively analyzed 179 consecutive ESRD patients who underwent AVF placement from 2008-2022 at a single tertiary academic center. Trans-thoracic or trans-esophageal echocardiograms were compared for each patient pre- and post-AVF placement. The median interval between echocardiograms was 2.3 years.

RESULTS:
AF was noted in 19.0% of patients prior to AVF placement. An additional 11.2% of the overall cohort developed AF during the study period (59% interval increase). Patients with AF were older (p=0.002), had greater body surface area (p=0.037), and were more likely to have a history of diabetes (p=0.01), but otherwise there were no significant differences in baseline comorbidities.

AVF placement was associated with a significant increase in LA maximum volume in the overall cohort (70.0+/-32.2 mL post-AVF from 52.1+/-21.0 mL pre-AVF, p<0.001). In patients with AF, LA maximum volume was significantly larger post-AVF compared to those without AF (79.7+/-28.7 vs 60.8+/-26.8 mL, p=0.004). LA strain was significantly lower in patients with AF pre-AVF (42.8+/-11.7% vs 52.5+/-13.6%, p<0.001) and post-AVF (39.9+/-13.1% vs 49.9+/-14.4%, p<0.001). Incidence of newly reduced left ventricular ejection fraction post-AVF was 13% in patients with AF (7/54) compared to 6.4% (8/125, p=0.146) in those without.

CONCLUSION:
Patients who undergo AVF placement for ESRD are at significant risk for subsequent development of AF, with adverse hemodynamic consequences. Close monitoring of cardiac rhythm, anatomy, and function is warranted in the post-AVF cohort. Additional studies to examine optimal management of this vulnerable population are needed.