#1819 Cardio-fistular recirculation in patients with chronic heart failure and preserved ejection fraction
Authors: Zulkarnaev Aleksei , Parshina Ekaterina , Fominykh Natalia , Stepanov Vadim , Fomin Aleksandr , Yankovoy Andrey , Vatazin Andrey , Popov Mikhail 
Published: May 2024

Abstract

Background and Aims
Cardio-fistular recirculation (CFR)—ratio of cardiac output (CO) to AVF volume blood flow (Qa)—is a well-known risk factor for death and cardiovascular adverse events. Currently, there are no clear limits for this index that definitely indicate AVF cardiotoxicity. In most cases, an interval score of &lt;20%, 20-30%, or &gt;30% is used to denote low, medium, and high risk, respectively. Typically, the assessment is performed on the interdialysiс day. HD sessions can cause significant hemodynamic changes, which may be important for patients with chronic heart failure (CFH) and preserved ejection fraction (EF), in whom the risk may be underestimated.
The aim of this prospective cohort study is to evaluate changes in heart structure and CFR in patients with СFH and preserved EF before and after an HD session.

Method
The study included 20 stable adult HD patients who met the inclusion criteria: CHF with preserved EF (50%), NYHA I-II, Qa ≥1 l/min, CFR &lt; 30%, interdialysiс weight gain &lt; 5%, eKt/V &gt; 1.2. Non-inclusion criteria: arrhythmias (except grade I AV block), NYHA III-IV, valvular disease (except mitral regurgitation I-II), intradialytic hypo/hypertension.
All patients underwent transthoracic ECHO-CG with tissue Doppler on the third day after the last HD session (Monday/Tuesday), one hour before and 2 hours after the HD session. In addition, we measured AVF volume blood flow—brachial artery Qa.

Results
Patient Descriptive Statistics: M/F 8/12, mean age 52.2 (SD 11.2, range 41-67) years, HD vintage 49 (11.1, 33-72) months, BMI 28.2 (3.8, 22.9-36.0) kg/m2, interdialysiс weight gain 3.2 (0.8, 1.9-4.7) kg, relative interdialysiс weight gain 4.1% (0.8, 2.9-4.9).
A significant trend in ECHO-CG parameters was observed, indicating a decrease in cardiac preload (Table 1).
Although there were no significant changes in EF, a pronounced decrease in CO was noted with a relatively stable Qa value.
As a result, 5 out of 20 patients had a CFR value of more than 30% after HD, which assigned them to a high-risk group.
As shown in Fig. 1, even patients with pre-HD CFR values less than 25% were classified as high-risk. Patients were intentionally examined after a long interdialysiс interval because this HD session is associated with the greatest hemodynamic changes. Some publications suggest that the risk of death after long interdialysic interval is significantly higher than that after short interval. Increase in CFR after HD probably has a synergistic deleterious effect with other risk factors. The severity of this influence is determined by both the maximum achieved CFR values and the rate of CO recovery.

Conclusion
Some patients have a significant increase in CFR after HD. However, the prognostic value of this phenomenon remains unclear.
In patients with significant CHF symptoms and normal or subnormal CFR on an interdialytic day, it is recommended to perform a post-HD examination. This can serve as a “stress test” to reveal any latent hemodynamic disadvantage caused by the AVF cardiotoxic effect.