Predictors and outcomes of cardiac complications following elective coronary bypass grafting

Acute kidney injury and chronic kidney disease after cardiac surgery

Kidney dysfunction is common after cardiac surgery and predicts mortality risk and poorer long-term outcome, particularly when acute injury superimposes upon chronic kidney disease. Numerous insults contribute to perioperative renal impairment including major surgical trespass, procedure-specific interventions (eg, deep hypothermic circulatory arrest), and postoperative complications. Regardless of cause, evidence supports a role for renal impairment and accumulation of "uremic toxins" as direct contributors to adverse outcome. No one has yet characterized a loss of renal function small enough to be insignificant. Despite considerable research focus, progress in development of interventions aimed at perioperative renoprotection has been disappointing. However, practice modifications can influence the likelihood of acute kidney injury, and several recent advances provide hope for the future. We review pathophysiologic understanding of this disorder; evaluate the confusing relationship (causal v epiphenomena) among acute kidney injury, chronic kidney disease, and adverse outcome after cardiac surgery; and provide an evidence-based assessment of the conduct of cardiac surgery and renoprotection strategies.

A single health status question had important prognostic value among outpatients with chronic heart failure

OBJECTIVE

Health status is an important marker of the impact of disease on function among patients with chronic heart failure (CHF). However, the prognostic value of CHF-specific health status on long-term mortality has not been adequately evaluated. Our objective was to assess CHF-specific health status and 5-year mortality among outpatients with CHF.

STUDY DESIGN AND SETTING

We analyzed data from 494 Veterans Affairs outpatients with diagnoses of CHF and objective evidence of left ventricular dysfunction who enrolled in a quality improvement intervention. We extracted information about comorbid diagnoses, severity of illness (Charlson index), health care utilization, drug therapy, laboratory, and vital sign data along with generic and CHF-specific health status. We then identified multivariate correlates of subsequent mortality at 5 years.

RESULTS

Five-year mortality was 44%. Age (chi2=26.1, hazard ratio [HR]=1.63, confidence interval [CI]: 1.35, 1.97; P<0.0001) and Charlson index (chi2=12.9, HR=1.39, CI: 1.16, 1.67; P=0.0003) were significantly associated with 5-year mortality. Controlling for clinical, lab, medication, and administrative data, a single-item assessing change in CHF-specific health status was independently associated with 5-year mortality (chi2=11.4, HR=0.87, CI: 0.80, 0.94, P=0.0007).

CONCLUSIONS

Given the strength of the association with mortality, health care providers should routinely assess this single-item change in health status among outpatients with CHF to identify higher risk patients and guide therapy.

Value of prolonged QRS duration as a predictor of low cardiac output syndrome in patients with impaired left ventricular systolic function who undergo isolated coronary artery bypass grafting

This study determined whether prolonged QRS duration (QRSd; > or =120 ms) is an independent predictor of low cardiac output syndrome (LCOS) in patients with low left ventricular (LV) ejection fraction (EF) who underwent isolated coronary artery bypass grafting (CABG). Abnormal LV systolic function places patients at greater risk for developing LCOS after isolated CABG. In patients with this form of ventricular function impairment, prolonged QRSd is associated with adverse hemodynamic effects. Clinical, operative, and outcome data from 190 consecutive patients with LVEF <50% who underwent isolated CABG (mean 62 +/- 9 years of age) were retrospectively analyzed. For all patients, preoperative QRSd was determined. LCOS was the primary outcome investigated. Fifty-seven patients (30%) developed LCOS. Compared with the subgroup without LCOS, the subgroup with this syndrome had significantly larger proportions of patients with LVEF <30% and prolonged QRSd. In addition, the group that developed LCOS had a longer mean QRSd (117 +/- 25 vs 102 +/- 17 ms, respectively, p = 0.00003) and a significantly higher frequency of adverse postoperative outcomes. Hospital stay was significantly longer in the subgroup with LCOS than in the subgroup without. Multivariate logistic regression analysis identified prolonged QRSd as the most significant predictor of LCOS. LVEF <30%, diuretic therapy, and preoperative risk score (European System for Cardiac Operative Risk Evaluation) were also identified as independent predictors of LCOS. In conclusion, in patients with impaired LV systolic function, prolonged QRSd is a highly significant predictor of LCOS development after isolated CABG.

Evidence-based renal protection in cardiac surgery

Acute renal dysfunction is a common serious complication of cardiac surgery. Although a diversity of mechanisms exist by which the kidney can be damaged during cardiac surgery, atheroembolism, ischemia-reperfusion, and inflammation are believed to be primary contributors to perioperative renal insult. In addition, the high metabolic demands of active tubular reabsorption and the oxygen diffusion shunt characteristic of renal circulation make the kidney particularly vulnerable to ischemic injury. Remote effects of acute renal injury likely contribute to the strong association of this condition with other major postoperative morbidities and mortality and justify the search for renoprotective agents, even when dialysis is never required. Nonpharmacologic preventive strategies include procedure planning that is based on risk stratification, avoidance of nephrotoxins, and meticulous perioperative clinical care, including optimizing intravascular volume and attention to modifiable risk factors such as minimizing hemodilution. Although numerous pharmacologic interventions to prevent or treat acute renal injury have shown promise in animal models, randomized placebo-controlled clinical trials that have looked at measures of significant adverse outcomes such as death and dialysis have not confirmed a benefit.

Perioperative Stroke and Long-Term Survival After Coronary Bypass Graft Surgery

BACKGROUND

Stroke is a devastating complication of coronary artery bypass graft (CABG) surgery. In-hospital outcomes have been described, yet the long-term effect of stroke on mortality following CABG surgery has not been well studied.

METHODS

We examined the survival of 35,733 consecutive patients undergoing isolated CABG surgery in northern New England from 1992 through 2001. Stroke was defined as a new fixed neurologic defect that persisted at least 24 hours after surgery. Patient records were linked to the National Death Index to assess mortality. There were 147,931 person years of follow-up and 5,705 deaths. Cox proportional hazard regression was used to calculate the adjusted hazard ratios (HR) and 95% confidence intervals (95% CI). We identified the 5-year survival stratified by primary stroke mechanism, the patient's functional impact, and discharge location among a subset of patients who had strokes between 1992 and 2000.

RESULTS

Perioperative stroke occurred in 575 patients (1.61%). Patients who had strokes had more comorbidities. After adjustments for differences in baseline patient and clinical characteristics, patients who had perioperative stroke were at a significantly increased risk for death (HR, 3.20; 95% CI, 2.80 to 3.66; p < 0.0001). Survival for patients with stroke at 1, 5, and 10 years was 83.0%, 58.7%, and 26.9%, respectively. Five-year survival decreased among patients who had major functional limitations before discharge, among those who had hypoperfusion strokes, and among patients who were discharged to locations other than home or rehabilitation facilities.

CONCLUSIONS

Perioperative stroke is associated with a very substantial increased risk of postoperative death among CABG surgery patients. The greatest risk of death was noted within the first year after surgery. Survival after 1 year approximates that of patients who did not suffer a stroke.

Certificate of need and the quality of cardiac surgery

Historically, states have used Certificate of Need (CON) programs to review proposals for new construction and expanded services in an effort to control costs and to improve the quality of and promote access to health care services. Congressional funding for CON ended in 1987. However, today, 26 states use CON to regulate cardiac surgery. There has been little evidence of the impact of CON on the quality of services. Pennsylvania is in a unique position to study the impact of CON on the quality and outcomes of care because the state terminated CON in 1996 and has publicly reported quality and outcomes data on coronary bypass graft (CABG) surgeries since 1992. Using a statewide inpatient data-reporting system, the volumes and outcomes of CABG surgeries at all Pennsylvania hospitals were examined in the 3 years prior to and the 3 years after the termination of CON. In the 3 years following the elimination of CON, the number of open-heart surgery programs increased 25%, yet there was no significant increase in the number of CABG surgeries performed. Quality, as measured by mortality rate, was not impacted by the real-location of the relatively stable CABG volume in the short term; this may be due, in part, to itinerant surgeons and statewide public performance monitoring. The long-term implications of deregulation are unclear and deserve future study.