Closing Dialysis Fistula After Transplant Halts Cardiac Remodeling

Marlene Busko

November 26, 2018

CHICAGO — Among stable patients after a successful kidney transplant, closing the arteriovenous fistula (AVF) that had been a conduit for dialysis resulted in reduced adverse cardiac remodeling over the next months in a new study.

Six months after AVF ligation, stable kidney transplant recipients showed a significant 14% decrease in left ventricular (LV) mass, as well as significant reductions in heart chamber volumes and levels of N-terminal pro b-type natriuretic peptide (NT-pro-BNP), a measure of ventricular wall stress.

Michael B. Stokes, MBBS, University of Adelaide, Royal Adelaide Hospital, Australia, presented findings from the randomized controlled Cardiac Remodeling Following Ligation of Arteriovenous Fistula in Stable Renal Transplant Recipients (AV Fistula) trial at the American Heart Association (AHA) Scientific Sessions 2018.

"These results have significant implications for the management of cardiovascular risk following kidney transplantation, given that a single intervention, undertaken in a day-procedure setting, has the potential to provide substantial cardiovascular benefits," Stokes told theheart.org | Medscape Cardiology.

The "data suggest that AVF ligation is associated with near-normalization of cardiac geometry in patients receiving the intervention, whereas control patients faced persisting and substantial deleterious remodeling which is recognized to portend adverse clinical outcomes," the researchers write.

"We propose elective AVF ligation be considered in all successful renal transplant recipients following a suitable period of clinical stability," they conclude.

However, the findings need to be confirmed in "a larger scale multicenter randomized control trial powered for clinical outcomes (morbidity and mortality as well as other cardiovascular outcomes such as heart failure and atrial fibrillation incidence)," in which they also look for any long-term effect on estimated glomerular filtration rate (eGFR) and blood pressure, Stokes said. The group is planning to conduct a follow-up trial.  

"It is an excellent proof-of-concept study," assigned discussant Maria Rosa Costanzo, MD, medical director, Edward Hospital Center for Advanced Heart Failure, Naperville, Illinois, told theheart.org | Medscape Cardiology in an email.

It "clearly shows that ligation of the AVF in stable renal transplant recipients leads to reduction in LV mass, reduction in all cardiac chambers' size, and no detrimental effects on the renal allograft function."

Moreover, "these findings are important," she continued, "because increased LV mass has repeatedly been shown to predict morbidity and mortality, not only in patients with renal disease, but in the general population as a whole."  

The next step, Costanzo agrees, is to confirm these findings in a longer "study that has clinically meaningful outcomes, including quality of life, functional capacity, morbidity, and mortality."

Cardiac Morphology in Nephrology Patients

Almost all patients on hemodialysis have an AVF, which can increase cardiac output by 10% to 20% and lead to adverse cardiac remodeling, said Stokes.

Closing this redundant AV fistula in patients who have had a successful kidney transplant could reduce this adverse cardiac remodeling, "potentially conferring an enormous mortality benefit in this group with a high CV burden," the researchers write.

However, some kidney transplant patients might prefer to keep a patent fistula, as "insurance," said Stokes, in case they need to go back on dialysis should their transplant fail. Or a nephrologist may see that a patient's transplant is not functioning well and prefer to keep a patent fistula.

There is no consensus about the value of AF ligation after a stable successful kidney transplant because this has not been well studied.

To investigate, the researchers enrolled 63 adults who had undergone successful kidney transplantation at least a year earlier and still had a functioning AVF, and randomly assigned them to undergo or not undergo surgical AVF ligation.

The primary outcome was change in LV mass at 6 months, and secondary outcomes included measures of ventricular and atrial volume, atrial area, NT-pro-BNP, and pulmonary artery peak velocity.

On average, the patients had the fistula for 10.5 years and had undergone transplantation 8.7 years earlier.

They had a mean age of 60 years and 67% were males. Just over a quarter had type 2 diabetes and 81% had hypertension.

The patients underwent cardiac MRI at baseline and 6 months later.

On average, in the AVF ligation group, LV mass decreased by 22.1 g (95% CI, –29.1 to –15.0), whereas in the control group, LV mass increased by 1.2 g (95% CI, –4.8 to 7.2; P < .001) over 6 months, for a difference of 14.7%.

Secondary outcomes of ventricular and atrial volume, atrial area, NT-pro-BNP, and pulmonary artery peak velocity were all significantly better in the group that had undergone AVF ligation.

There was no significant change in eGFR, "which is important," Costanzo said, because "previous analyses had suggested that closure of the AV fistula in stable renal transplant recipients might worsen allograft function."

There was also no change in blood pressure, and there were minimal surgical complications: six patients had thrombosis and erythema that resolved with rest and anti-inflammatory medication; and two patients had infection over the suture lines that were managed with oral antibiotics. No patient required admission or surgical reintervention.

The trial was funded by a grant from the Royal Adelaide Hospital Research Foundation. Stokes and Costanzo have no relevant financial disclosures.

American Heart Association (AHA) Scientific Sessions 2018: Abstract 19322. Presented November 11, 2018.

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