Remote ischemic preconditioning has a neutral effect on the incidence of kidney injury after coronary artery bypass graft surgery.

Acute kidney injury (AKI) is a frequent complication of cardiac surgery and usually occurs in patients with preexisting chronic kidney disease (CKD). Remote ischemic preconditioning (RIPC) may mitigate the renal ischemia-reperfusion injury associated with cardiac surgery and may be a preventive strategy for postsurgical AKI. We undertook a randomized controlled trial of RIPC to prevent AKI in 86 patients with CKD (estimated glomerular filtration rate under 60 ml/min per 1.73 m(2)) undergoing coronary artery bypass graft (CABG) surgery. Forty-three patients each were randomized to receive standard care with or without RIPC consisting of three 5-minute cycles of forearm ischemia followed by reperfusion. The primary end point was the development of AKI defined as an increase in serum creatinine concentration over 0.3 mg/dl within 48 h of surgery. Secondary end points included a comparison between the study and control groups of several serum biomarkers of renal injury including cystatin-C, neutrophil gelatinase-associated lipocalin (NGAL), and interleukin-18 (IL-18), and urinary biomarkers including NGAL, IL-18, and kidney injury molecule-1 measured at 6, 12, and 24 h after CABG, and the 72-h serum troponin T concentration area under the curve as a marker of myocardial injury. Clinical and operative characteristics were similar between the preconditioned and control groups. AKI developed in 12 patients in both groups within 48 h of CABG. There were no significant differences between the two groups in the concentrations of any of the serum or urinary biomarkers of renal or cardiac injury after CABG. Thus, RIPC induced by forearm ischemia-reperfusion had no effect on the frequency of AKI after CABG in patients with CKD.

The impact of acute kidney injury on midterm outcomes after coronary artery bypass graft surgery: a matched propensity score analysis.

BACKGROUND: The development of acute kidney injury (AKI) after coronary artery bypass graft (CABG) surgery is associated with increased short- and long-term mortality. Whether AKI has a causal relationship with subsequent mortality or whether the development of AKI simply occurs in patients with more comorbidity undergoing more complex procedures remains unresolved. METHODS AND RESULTS: This was an observational cohort study of prospectively collected data from 4694 patients discharged from the hospital after first-time CABG surgery at a tertiary cardiac center between 2003 and 2008. AKI was defined using the Risk, Injury, Failure, Loss, and End stage (RIFLE) criteria, which require at least a 50% increase in serum creatinine. The primary outcome measure was all-cause mortality determined via UK Office of National Statistics. A total of 562 (12.0%) of patients developed AKI after CABG surgery. Patients who developed AKI were older, more likely to be female, and had more comorbidity than patients who did not develop AKI. In a Cox multivariable analysis, the development of AKI was an independent predictor of midterm mortality (hazard ratio, 1.80; 95% confidence interval, 1.50-2.16). Subsequently, a comparison of 562 patients who sustained AKI with 562 propensity score-matched patients who did not sustain AKI was undertaken. After propensity matching, baseline clinical and operative characteristics were similar between both groups. After Cox multivariable analysis of the propensity-matched cohort, AKI remained an independent predictor of midterm mortality (hazard ratio, 1.52; 95% confidence interval, 1.19-1.93). CONCLUSIONS: The development of AKI after CABG is a serious event associated with worse midterm survival. This excess mortality cannot be explained simply by coexisting comorbidity and surgical complexity.

Impact of diabetes mellitus and renal insufficiency on 5-year mortality following coronary artery bypass graft surgery: a cohort study of 4869 UK patients.

OBJECTIVES: Diabetes mellitus (DM) and renal impairment (RI) are both independent predictors of mortality after coronary artery bypass graft surgery (CABG). The two conditions often coexist, yet the impact on long-term prognosis after CABG of each factor relative to the other and the two in combination is uncertain. METHODS: We undertook a prospective cohort study of 4869 patients who underwent CABG between 2003 and 2007. The cohort was divided into four groups according to preoperative diabetic status and renal function: patients without either DM or RI (reference group), patients with DM alone, patients with RI alone and patients with both DM and RI. Clinical outcomes were compared between groups. Patients receiving renal replacement therapy were excluded. The primary outcome was 5-year all-cause mortality. RESULTS: The crude 5-year all-cause mortality rate was 9.0% for patients in the reference group, 11.1% for patients with DM alone, 20.3% for patients with RI alone and 28.5% for patients with both DM and RI (P < 0.0001). Five-year survival adjusted for potential confounding factors was significantly worse for patients with DM (hazard ratio (HR) 1.30; 95% confidence interval (CI) 1.06-1.59), patients with RI (HR 1.32; 95% CI 1.08-1.61) and patients with both DM and RI (HR 2.04; 95% CI 1.65-2.53) when compared with patients with neither condition. CONCLUSIONS: Preoperative DM and RI were important predictors of 5-year mortality after CABG. Patients with RI alone had a higher mortality rate than patients with DM alone, but this difference was largely accounted for by age and other comorbidities. The combination of DM and RI doubled the 5-year mortality rate after CABG independently of potential confounding factors.

Diagnosis and management of patients with acute cardiac symptoms, troponin elevation and culprit-free angiograms.

Patients with acute cardiac symptoms, elevated cardiac troponin and culprit-free angiograms comprise a significant proportion of patients admitted with presumed acute coronary syndromes (ACS). International guidelines recommend that these patients receive lifelong secondary prevention under the presumption that angiographically undetectable coronary artery disease is the likeliest cause for their presentation. Recent studies using cardiac MRI suggest myocarditis to be the most common cause of these presentations. Emerging data also suggest that myocarditis presenting like an ACS may not be benign. In this article the current literature on patients presenting with acute cardiac symptoms, elevated cardiac troponins but culprit-free angiograms is reviewed, focusing on the diagnostic utility of cardiac MRI in this cohort, and the importance of diagnosing acute myocarditis. The development of higher sensitivity troponin assays will undoubtedly lead to an increase in the number of patients with presumed ACS but culprit free angiography. Robust management pathways including cardiac MRI are vital for cardiac centres dealing with these patients in order to achieve cost-effective, individualised patient care.