Interventions Required in AVFs versus AVGsInterventions Required in AVFs versus AVGs

Dallas—Increased placement of arteriovenous fistulas (AVF) has lead to increased non-maturing AVF requiring intervention prior to cannulation more frequently than arteriovenous grafts (AVG). That was one of the findings of a study conducted recently by James Harms, MD, and colleagues. Study results were reported during a poster session at the NKF Spring Clinical meetings in a poster titled Impact of Intervention to Promote Maturation on Survival of Arteriovenous Fistulas and Grafts.

Once they achieve maturity, AVF have longer cumulative survival and require fewer interventions compared with AVG, and national guidelines suggest increasing the prevalence of AVF among patients on maintenance hemodialysis. The increased placement of AVF has led to increased frequency of non-maturing AVF requiring intervention to achieve maturity, diminishing cumulative survival and increasing the need for procedures to maintain patency.

This study was designed to compare (1) the cumulative survival of AVF and AVG and (2) the frequency of intervention necessary for maintaining patency in AVG and AVF that did and did not require intervention prior to successful use for dialysis. The researchers identified 599 patients in the vascular database at the University of Alabama at Birmingham who received a new vascular access (AVF or AVG) following initiation of hemodialysis via a central venous catheter over a 6-year period.

The database provided data on whether the access was successfully cannulated, whether an access intervention was required prior to successful use of the access, whether and when the access was permanently abandoned, and the number of interventions performed following use of the access. Medical records provided patient demographics and comorbidities; differences among patient subgroups were analyzed by t-tests for continuous variables and Chi-square tests for categorical values.

Among the 599 patients, 289 had AVF and 310 had AVG. AVF were more likely to require intervention in patients who were female (odds ratio [OR], 2.94, 95% confidence interval [CI], 1.75-5.00; P<.001) or had diabetes mellitus (OR, 1.74; 95% CI, 1.09-2.79; P<.05). AVG were more likely to require intervention in patients who were not hypertensive (OR, 0.33; 95% CI, 0.12-0.89; P<.05), had coronary artery disease (OR, 2.03, 95% CI, 1.11-3.71; P<.05), or had peripheral vascular disease (OR, 1.96; 95% CI, 1.01-3.83; P<.05).

In 17.7% of AVG, intervention was required prior to successful use, compared with 50.5% of AVF. Further, 82.3% of AVG were used successfully without intervention, compared with 49.5% of AVF.

Access survival was shorter for AVF with prior intervention than AVF without interventions (hazard ratio [HR], 1.84; P<.001); access survival was shorter for AVG with prior interventions compared with AVG without intervention (HR, 1.98; P<.001); access survival was worse for AVF with prior interventions than for AVG without prior interventions (HR, 1.45; P=.01).

“Intervention prior to successful cannulation predicts a significantly increased requirement for interventions to maintain patency, as well as diminished cumulative survival. AVF placement predisposed to longer catheter dependence and higher rates of catheter-related bacteremia. Most AVG do not require intervention prior to cannulation, and these AVG have longer cumulative survival than AVF which do require intervention prior to cannulation. AVG deserve greater consideration as first access placement for patients who have already initiated hemodialysis via a catheter,” the researchers said.

Source: Harms J, Rangarajan S, Young CJ, Barker-Finkel J, Allon M. Impact of intervention to promote maturation on survival of arteriovenous fistulas and grafts. Poster presented at the National Kidney Foundation Spring Clinical Meetings, Dallas, Texas, March 25-29, 2015.