Coronary Artery Revascularization in Chronic Kidney Disease

Abstract

C oronary artery revascularization procedures, performed via coronary artery bypass grafting (CABG) or percu-taneous (PCI) methods, are among the most commonly performed therapeutic interventions worldwide with >1 million performed annually in the United States alone. 1 The relative merits of each approach have been examined in numerous landmark clinical trials that inform practice guidelines and daily clinical decision making. 2-5 Although the percutaneous comparator to CABG in early studies usually included balloon angioplasty or bare metal stents, recent studies reflect iterative advances in both stent technology and contemporary medical therapy. Despite this large evidence base, however , routine exclusion of patients with underlying chronic kidney disease (CKD) persists in many clinical trials. In the Bypass Angioplasty Revascularization Investigation in Type 2 Diabetes (BARI 2D) and Future Revascularization Evaluation in Patients With Diabetes Mellitus: Optimal Management of Multivessel Disease (FREEDOM) studies, for example, patients were excluded with serum creatinine levels exceeding 2 mg/dL and severe renal disease, respectively. 2 The public health implication of such systematic under-representation is highlighted by the fact that CKD is present in >40% of all patients undergoing PCI and ≈30% of those receiving CABG. 6,7 In addition, renal dysfunction confers a strong, independent , and graded risk for morbidity and mortality after PCI or CABG. The high prevalence of CKD in patients requiring revascularization, coupled with the excess cardiac risk associated with this condition, has motivated consensus statements and clinical investigations examining the impact of PCI and CABG in this high-risk population. 8,9 See Article by Chan et al It is within the context that Chan et al 10 have reported their findings comparing CABG to PCI with drug-eluting stents (DES) in a large cohort of patients with CKD in this issue of Circulation: Cardiovascular Interventions. Using data from a provincial registry in Ontario, Canada, the authors identified 4006 patients with CKD and multivessel coronary artery disease undergoing index revascularization between 2008 and 2011. Most patients (n=3010) underwent CABG, whereas PCI with DES was performed in 996. The cohort reflected the high prevalence of comorbid risk factors expected in patients with CKD with an average age of ≈75 years and diabetes mellitus present in >40% of participants. Of note, few patients (n=211; 5.3%) were receiving dialysis at the time of revascularization. Patients were followed up for an average of ≈2 years and the authors compared early and late clinical outcomes between groups in the overall sample and in a propensity-matched cohort. Independent predictors of late adverse events were identified using multivariable modeling. Salient findings from this report include a substantial advantage for CABG over PCI that emerged as early as 30 days, lack of differences in stroke rates between groups, and an independent hazard for late adverse events associated with DES use. Findings were unchanged in the propensity-matched cohort and persisted after multivariable adjustment. As CKD is associated with a unique and diffuse athero-sclerotic phenotype, these results are concordant with the current revascularization paradigm favoring CABG over PCI in patients with diffuse or complex coronary artery disease. Randomized trial data, for example, has demonstrated the accentuated benefits of CABG over PCI with DES in other patient cohorts with extensive atherosclerosis, such as diabetes mellitus or those with intermediate to high Synergy Between PCI With TAXUS and Cardiac Surgery (SYNTAX) scores. 2,11 Although patients were matched for degree of coronary artery disease in this study, nonobstructive and angio-graphically inapparent disease is strongly linked with risk for subsequent adverse events 12 and provides a rationale for more complete revascularization with CABG in patients with diffuse atherosclerosis. The current report is also consistent with and extends previous comparisons between CABG and PCI performed in dialysis cohorts. 8,9 Although these earlier studies suggested an advantage for CABG over PCI in dialysis patients, the magnitude of benefit observed by Chan et al in their predominantly nondialysis population is much larger than that observed in the setting of dialysis-dependent CKD. More specifically, Chan et al demonstrated an absolute unadjusted 7.4% reduction in late mortality risk, substantially higher than the 3% difference noted by Charytan et al 8 at a similar time point. These differences may reflect excess mortality risk after CABG in the early postsurgi-cal period in patients with versus without dialysis, thereby mitigating long-term benefits from surgical bypass. Alternatively, (Circ Cardiovasc Interv. 2015;8:e002140.