Faculty Bibliography

BACKGROUND:Improved understanding of the incidence and risk factors for operative complications and long-term mortality following coronary artery bypass grafting (CABG) is needed to better define the optimal role for CABG in patients with chronic kidney disease (CKD). METHODS:We analysed 2438 patients who underwent CABG at a single centre between 2005 and 2008. Multivariable regression was used to analyse associations and to generate a CKD-specific predictive tool. RESULTS:Operative mortality was 4.8% in individuals with stage 3 CKD, 7.1% in individuals with stage 4-5 CKD and 2.2% in those without significant CKD (P < 0.001). CKD was associated with post-operative blood transfusion, acute kidney injury, myocardial injury and cardiac arrest, and use of exogenous blood and acute kidney injury were strongly associated with in-hospital death in CKD patients. Patients with stage 3 (HR 1.64, 95% CI 1.30-45.94) and stage 4-5 CKD (HR 2.77, 95% CI 1.00-2.68) were more likely to die during follow-up than those without CKD, but mortality rates were low among patients who survived to discharge-stage 3 (0.006 deaths/year) and stage 4-5 CKD (0.009/year). A scoring system including urgent or emergent surgery (OR 2.30), prior cardiac surgery (OR 3.06), concurrent valve surgery (OR 2.06), preoperative shock (OR 6.18), and prior stroke (OR 1.98) had 96.4% percent specificity for the detection of in-hospital death in patients with CKD. CONCLUSIONS:Perioperative mortality and morbidity remain more frequent in patients with stage 3-5 CKD than patients with preserved renal function, but long-term outcomes in patients surviving hospitalization are favourable. We have developed a predictive tool that holds promise as a means of identifying CKD patients most likely to survive surgery and benefit from CABG.

Whether drug-eluting stents are effective and safe in patients with moderate renal insufficiency (RI) is unknown. We performed a pooled analysis of data from 3 blinded randomized trials of sirolimus-eluting stents (SESs) versus bare metal stents (BMSs; SIRIUS, C-SIRIUS, E-SIRIUS) that included 1,510 patients. Clinical and angiographic outcomes were stratified by the presence of RI defined by creatinine clearance calculated by the Cockcroft-Gault formula (normal >/= 90, mild 60 to 89, moderate < 60 ml/min). Patients with baseline creatinine > 3.0 mg/dl were excluded from these trials. Baseline mild RI was present in 517 patients (34.7%, mean creatinine clearance 75.7 ml/min) and moderate RI in 228 patients (15.3%, mean creatinine clearance 47.2 ml/min). Treatment with SESs resulted in lower rates of 8-month angiographic restenosis rates in patients with RI (mild RI 6.7% vs 42.6%, p < 0.001; moderate RI 9.7% vs 39.7%, p < 0.001) and without baseline RI (7.7% vs 37.2%, p < 0.001). One-year target vessel revascularization rates were similarly decreased with SESs in patients with (mild RI 4.7% vs 24.2%, p < 0.001; moderate RI 5.5% vs 26.9%, p < 0.001) and without (8.1% vs 22.4%, p < 0.001) RI, and this benefit was maintained at 5 years. Compared to patients with normal or mild RI, patients with moderate RI had higher rates of overall mortality and cardiac death at 1 year and 5 years (death 2.6% vs 0.6%, p <0.01, and 17.5% vs 6.3%, p < 0.01, at 1 year and 5 years, respectively; cardiac death 1.3% vs 0.2%, p = 0.05, and 6.6% vs 3.4%, p = 0.04, at 1 year and 5 years, respectively). However, there was no differential effect of SESs versus BMSs on any safety end point. In conclusion, patients with moderate RI have a nearly threefold increase in 5-year mortality after percutaneous coronary intervention compared to patients without RI. The effectiveness of SESs in decreasing restenosis compared to BMSs in patients with moderate RI was preserved and rates of death and myocardial infarction were not adversely affected.

BACKGROUND AND OBJECTIVES/OBJECTIVE:In the general population, an early invasive strategy of routine coronary angiography is superior to a conservative strategy of selective angiography in patients who are admitted with unstable angina or non-ST segment elevation myocardial infarction (MI), but the effectiveness of this strategy in individuals with chronic kidney disease (CKD) is uncertain. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS/METHODS:We conducted a collaborative meta-analysis with data provided by the main authors of identified trials to estimate the effectiveness of early angiography in patients with CKD. The Cochrane, Medline, and EMBASE databases were searched to identify randomized trials that compared invasive and conservative strategies in patients with unstable angina or non-ST MI. Pooled risks ratios were estimated using data from enrolled patients with estimated GFR <60 ml/min per 1.73 m(2). RESULTS:Five randomized trials that enrolled 1453 patients with CKD were included. An early invasive strategy was associated with nonsignificant reductions in all-cause mortality, nonfatal MI, and a composite of death or nonfatal MI. The invasive strategy significantly reduced rehospitalization. CONCLUSIONS:This collaborative study suggests that the benefits of an early invasive strategy are preserved in patients with CKD and that an early invasive approach reduces the risk for rehospitalization and is associated with trends of reduction in the risk for death and nonfatal re-infarction in patients with CKD. Coronary angiography should be considered for patients who have CKD and are admitted with non-ST elevation acute coronary syndromes.

Patients with chronic kidney disease have high rates of myocardial infarction and death following an initial attack. Proximal location of coronary atherosclerotic lesions has been linked to the risk of acute myocardial infarction and to infarction-associated mortality. To examine if the spatial distribution of lesions differs in patients with and without chronic kidney disease, we used quantitative coronary angiography to measure this in patients with acute coronary thromboses who were having angiography following acute myocardial infarction. Multivariable linear regression was used to adjust for differences in baseline characteristics. Among 82 patients with stage 3 or higher chronic kidney disease, 55.6% of lesions were located within 30 mm and 87.7% were within 50 mm of the coronary ostia. This compared to 34.7 and 71.8%, respectively, among 299 patients without significant kidney disease. Chronic kidney disease was independently and significantly associated with a 7.0 mm decrease in the distance from the coronary ostia to the problem lesion. Our study suggests that a causal link between a more proximal culprit lesion location in patients with chronic kidney disease and their high mortality rates after myocardial infarct is possible and may have important implications for interventions to prevent infarction.

Patients with chronic kidney disease (CKD) have high mortality following myocardial infarction (MI), but are less likely to undergo coronary angiography than those without CKD. Whether this phenomenon is explained by differences in the presentation of MI or by bias against performing coronary angiography in patients with CKD is unclear. We examined the clinical presentation of 1876 elderly patients who presented with MI and categorized them by estimated glomerular filtration rate: >60 ml/min (no/mild CKD), 30-60 ml/min (CKD Stage 3) or <30 ml/min (CKD Stage 4/5). Compared with patients with no/mild CKD, patients with CKD Stage 3 or Stage 4/5 had more comorbidity, greater prior nursing home use, and higher frequency of conduction abnormalities or anterior infarction. By contrast, peak creatinine kinase-MB fraction (CK-MB) concentrations were lower and ST-elevation MI was less common in patients with CKD Stage 3 or Stage 4/5. In univariate analyses, patients with CKD Stage 4/5 (odds ratio (OR)=0.34, 95% confidence interval (CI): 0.23-0.50) or Stage 3 (OR=0.57, 95% CI: 0.45-0.73) were markedly less likely to undergo angiography than subjects with no/mild CKD. After multivariable adjustment, the association of CKD Stage 3 with the use of coronary angiography was attenuated (OR=0.78, 95% CI: 0.60-1.03), but CKD Stage 4/5 remained strongly associated with lower use (OR=0.52, 95% CI: 0.34-0.80). Clinical features of MI are different in patients with and without CKD and may partly explain the low use of angiography in patients with CKD Stage 3. However, the clinical features of MI do not account for its underuse in MI patients with CKD Stages 4/5. Whether reduced use of angiography in patients with advanced CKD is justified must be evaluated in formal risk-benefit analyses.

BACKGROUND:Rates of restenosis following percutaneous coronary intervention with stent placement are high in patients with advanced renal failure. Whether mild to moderate chronic kidney disease (CKD) is associated with a similarly increased need for short or long-term target lesion revascularization (TLR) following coronary stenting is uncertain. METHODS:We analysed results from 1228 patients enrolled in four separate, randomized, controlled clinical trials who underwent elective coronary angioplasty with stenting and were prospectively followed for 5 years after the index procedure. Cox proportional hazards regression was used to correct for confounding and to estimate the short and long-terms risks of target lesion revascularization in patients with vs without mild to moderate CKD. RESULTS:During a median follow-up of 5 years, 205 patients (16.7%) required TLR with 59 (4.8%) requiring TLR after the first year. Mild (HR 1.07, 95% CI 0.74-1.53) and moderate (HR 0.95, 95% CI 0.552-1.64) CKD were not associated with an increase in the adjusted, overall-risk of TLR. However, mild to moderate CKD was associated with a non-significantly increased risk of late TLR (HR 1.40, 95% CI 0.73-2.69). CONCLUSIONS:Coronary stenting appears to be similarly effective in patients with mild to moderate CKD and patients with normal renal function. While target lesion revascularization is rarely needed beyond the first year after revascularization, long-term results of coronary stenting may be less-favourable in patients with CKD.