A new study probing which chronic kidney disease (CKD) patients would benefit most from renal artery stenting points toward those who experience a more rapid decline in renal function over six months prior to the procedure.
It is an area that has been a source of great frustration for vascular surgeon John Gregory Modrall (University of Texas Southwestern Medical School, Dallas, USA), ever since, in 2014, the CORAL (Cardiovascular outcomes in renal atherosclerotic lesions) trial established no benefit from renal artery stenting over medical therapy in patients with CKD. It created, the professor of surgery told Renal Interventions, “a state of therapeutic nihilism, if you will, in our specialty on how to manage people with renal artery stenosis, and either hypertension or CKD.” Why? The patients kept coming, he said. And vascular surgeons were left with less certainty regarding how they should treat them, he said.
So Modrall and colleagues set about identifying putative predictors to be able to select patients for renal artery stenting who are most likely to benefit. They dug into the Veterans Affairs Corporate Data Warehouse to find 695 patients who underwent renal stenting between 2000 and 2021, categorising them as “responders” if eGFR (estimated glomerular filtration rate) at 30 days or greater post-stenting increased 20% compared to pre-stenting. All others were “non-responders.”
The results were stark. Presented at the 2023 Southern Association for Vascular Surgery (SAVS) annual meeting (18–21 January, Rio Grande, Puerto Rico), they revealed that patients in CKD stages 3b and 4 (eGFR 15-44 mL/min/1.73m2) are the only sub-groups with a significant probability of improved renal function after renal stenting, with the rate of decline of preoperative eGFR over the months prior to stenting a powerful discriminator of patients who are most likely to benefit.
“Both of those are helpful to clinicians because we can then look at the patient’s history of where their renal function is currently when we see them in the office, and where it’s been for the last six–nine months,” Modrall explained, “and we can make a much more educated estimation of the probability of improved renal function when we stent them.
“By the same token, on the flip side of that is, if a patient has, for instance, very flat renal function over six or nine months prior to stenting, we can tell the patient that the probability of improved renal function is so low that it doesn’t even merit the treatment. That’s a huge help to clinicians.”
The third—and negative—predictor, the research team uncovered in the study, is diabetes, Modrall continued. “This turned out to be an interesting finding that we have now seen in two successive studies with different datasets,” he said. “What that tells us is that, probably, with many patients with diabetes, their kidney is probably already too injured to benefit from stenting. While we’re not saying you shouldn’t stent those patients, we certainly would say you should be very circumspect and careful about choosing patients for stenting if they have diabetes.”
Importantly, Modrall pointed out, the predictors highlighted in the study are “putative,” or “candidate predictors,” that have not been validated in a prospective series. “The next step is to take the data from this study, combine it with two of our prior studies, and in doing so we will have close to 1,800 patients with renal artery stents,” he said. “That represents the single largest dataset of renal artery stenting patients in existence to my knowledge.”
Modrall and his team hope to then leverage the enlarged dataset to create an outcome prediction tool that clinicians could use in practice. He envisages a desktop- or phone-based application into which a patient’s parameters could be inputted in order to establish a probability of improved renal function. “We’re not there yet; we don’t with 100% certainty know that that would be feasible,” Modrall conceded. “But that is the goal, and that is where we are beginning to work currently.”
Modrall believes the study also showcased the “unique partnership” between an academic institution, University of Texas Southwestern, and a Veterans Affairs (VA) facility, the Dallas VA Medical Center, where he also holds an appointment. “This really benefits both facilities, both institutions and all of their patient populations,” he added.