CTO PCI Patients With CKD Have More Acute Kidney Injury but Not Dialysis or TLF Over 2 Years

SAN DIEGO, CA—One-fifth of patients undergoing PCI for a chronic total occlusion (CTO) have chronic kidney disease (CKD), according to new registry data. However, while the incidence of contrast-induced acute kidney injury (CI-AKI) was almost doubled for patients with CKD, this did not lead to higher rates of new dialysis or target lesion failure over follow-up.

Lorenzo Azzalini, MD, PhD (San Raffaele Scientific Institute, Milan, Italy), who presented the results Friday at TCT 2018, told TCTMD that these results should encourage dedicated CTO operators in that they “should not be scared” to perform this procedure in patients with CKD. Rather, good results can be achieved by paying attention to identifying high-risk patients, using intravenous hydration, avoiding ad hoc procedures, setting a maximum contrast level, and defaulting to a retrograde approach, he stressed.

The study, also appearing in the October 2018 issue of the Canadian Journal of Cardiology, included 1,092 patients—19.6% with CKD, defined as an eGFR of ≥ 60 mL/min/1.73 m2—receiving CTO PCI at five centers in four countries between July 2011 and June 2017. Patients with CKD had a greater incidence of moderate or severe calcification (51% vs 42%; P = 0.02) and received less contrast (272 vs 319 mL; P < 0.001). However, both technical success (79% vs 87%; P = 0.001) and procedural success (79% vs 86%; P = 0.008) were lower for patients with CKD compared with those without.

The overall rate of CI-AKI—defined as an increase in serum creatinine ≥ 0.3 mg/dL or ≥ 50% from baseline within 72 hours—was 9.1%, and it was nearly twofold higher for CKD patients (15.0% vs 7.8%; P = 0.001). Notably, CI-AKI requiring dialysis was only observed in one patient in the CKD arm.

In-hospital death was more common for CKD patients as well (0.9% vs 0.1%; P = 0.04), but there were no other differences in in-hospital outcomes between the study arms. For patients with CI-AKI, there were greater rates of in-hospital vascular complications (6.2% vs 1.1%; P < 0.001), major bleeding (2.1% vs 0.3%; P = 0.02), and death (2.1% vs 0.1%; P = 0.001), compared to those without.

After 24 months of follow-up, CKD patients still had a higher rates of all-cause mortality (11.2% vs 2.7%; P < 0.001) and cardiac mortality (6.7% vs 1.2%; P < 0.001) and need for dialysis (1.1% vs 0.1%; P = 0.03), but there was no difference in target lesion failure (12.4% vs 10.5%; P = 0.47). Results were similar for patients stratified by CI-AKI status, but there was no significant difference observed for dialysis. Lastly, CI-AKI was not an independent predictor of either target lesion failure or death at follow-up.

Complications vs Contrast

In a panel discussion following the study presentation, Todd Brinton, MD (Stanford University Medical Center, CA), said “this data reinforces what I think we already know, which is patients with renal disease particularly are a sicker patient population. The encouraging thing is despite the incidence of renal dysfunction, we don't put patients on dialysis.”

Panel co-chair Jeffrey Moses, MD (NewYork-Presbyterian/Columbia University Irving Medical Center, NY), said the “remarkable” part of the results is the comparatively high amount of contrast used overall, “and yet your outcomes are actually pretty good. It looks like a lot of this may be driven by the complications per se, and not the contrast. I'm not saying we should liberalize the contrast, but I think we have an opportunity to do even better and that CKD should not really be a major influence in your decision to revascularize, especially given your association of procedural success and your strikingly low mortality.”

On the other hand, panel co-chair George Vetrovec, MD (VCU Pauley Heart Center, Richmond, VA), said “it’s a little difficult to be sure about the safety because my guess is this is a sicker population and there may be some reluctance on revascularization until later in their course. . . . I’m not sure it’s open season quite yet.”

Because of the way the database is set up, Azzalini replied that it is indeed difficult to ascertain what is driving the level of sickness in the patient population beyond CKD. “What I can tell you is that the rate of mortality on follow up at 2 years is strikingly higher, 11.2% vs 2.7%, almost four times higher, so this is something that has already been shown in the non-CTO PCI [population], but it is also present here.”

Prior data have shown “the late effect of complications on mortality, so this is a lower success population,” Moses added. “That may impact mortality. I wouldn't just attribute it to disease process alone.”

Looking forward, Azzalini told TCTMD that he would like to see more studies focused on the identification of risk factors for developing contrast-induced nephropathy in the CTO PCI population. “If we could have a specific risk score [that] outperforms the risk score for the overall population, such as the Mehran risk score or the NCDR risk score, maybe this could be more tailored to our population,” he said. Even before doing that, he added, these all-comers scores should be validated in CTO PCI patients.

Azzalini is also keeping an eye out for new technologies that will aid in the performance of CTO PCI. For example, he said the DyeVert Plus system, which is designed to divert any excess contrast away from the aortic root, holds promise. Also, the role of mechanical support in preventing acute kidney injury in patients with heart failure and decreased LVEF remains to be explored, Azzalini said. “We have understood in the last few years that the main driver of contrast-induced nephropathy is not contrast, it is renal hyperperfusion. So all events that create hyperperfusion of the kidneys . . . during the procedure, if we can avoid those events, we can actually decrease the risk of CI-AKI.”