A new study indicates that patients with mild-to-moderate chronic kidney disease do not have worse outcomes after undergoing percutaneous coronary intervention (PCI) with a second-generation drug-eluting stent than patients with preserved renal function. Studies of PCI with a first-generation drug-eluting stent indicated that patients with any level of renal impairment had worse outcomes after PCI.
Writing in JACC: Cardiovascular Interventions, Joo Myung Lee (Division of Cardiology, Department of Internal Medicine, Heart Vascular Stroke Institute, Samsung Medical Center, Seoul, South Korea) and others comment that studies of bare metal stents and first-generation drug-eluting stents have indicated that the presence of chronic kidney disease increases the risk of worse outcomes after PCI. However, they add that “the usage of second-generation drug-eluting stents in chronic kidney disease patients has not been fully evaluated”. Therefore, using data from the Korean multicentre drug-eluting stent registry, they evaluated the clinical impact of chronic kidney disease—stratified by severity—on clinical outcomes.
Of 12,426 patients in the registry, 2,927 patients had chronic kidney disease. Of these, 79.6% had mild-to-moderate disease and 20.4% had severe disease or end-stage renal disease. Overall, Lee et al report, the incidence of target lesion failure—the primary endpoint—was significantly higher among those with chronic kidney disease: 11.9% vs. 4.9% for patients with preserved renal function (p<0.001). A second endpoint, patient-oriented composite outcome (POCO; including all-cause mortality, any myocardial infarction, and any revascularisation) was also significantly higher in the chronic kidney disease group (22.2% vs. 12.9%; p<0.001).
The authors found that both the incidence of target lesion failure and POCO gradually increased with chronic kidney disease severity. The authors comment: “After multivariate adjustment, severe chronic kidney disease and end-stage renal disease patients had significantly higher risk of target lesion failure and POCO, whereas mild-to-moderate chronic kidney disease had a comparable risk of target lesion failure or POCO compared with those with preserved renal function.” They add: “The cutoff value of estimated Glomerular Filtration Rate (eGFR) to predict adverse outcome after PCI using a second-generation drug-eluting stent was 40 to 45ml/min/1.73m2.”
According to Lee et al, studies of PCI with a first-generation drug-eluting stent in patients with chronic kidney disease “uniformly showed” an increase of adverse events “as renal function deteriorated even in patients with mild renal impairment”. They note that their study, which has “new and intriguing results”, indicates that “only severe chronic kidney disease or end-stage renal disease patients were at significantly higher risk of target lesion failure or POCO”.
“Considering these results, we could conclude that second-generation drug-eluting stents do better in chronic kidney disease patients, whereas those with eGFR <40 to 45ml/min/1.73m2, especially those dialysis-dependent patients (ie. end-stage renal failure), still remain as the most vulnerable subset, needing meticulous caution regarding the revascularisation strategy and follow-up care,” Lee et al summarise.
Study author Hyo-Soo Kim (Seoul National University Hospital, Seoul, Korea) told Cardiovascular News: “I believe that the renal function impairment is a risk factor of the atherothrombotic process in coronary artery that is the underlying pathophysiology of POCO or target vessel failure after PCI (death, infarction, or revasculariszation). The magnitude of risk may be dependent on the severity of renal impairment.
Thus the more severely impaired the renal function is, the more frequent the POCO or target vessel failure is. POCO is more frequent even with the excellent contemporary drug-eluting stents in the patients with severe renal impairment than in those with normal function. The reason why we could not observe the difference of POCO between patients with mild renal impairment and those with normal function is the low event rate with the excellent contemporary drug-eluting stents. Such low incidence could not make the subtle difference of clinical outcomes significant between patients with a mildly impaired kidney and those with a normal one.”