Imtiaz S. Ali

Coronary-Artery Bypass Surgery in Patients with Left Ventricular Dysfunction

BACKGROUND The role of coronary-artery bypass grafting (CABG) in the treatment of patients with coronary artery disease and heart failure has not been clearly established. METHODS Between July 2002 and May 2007, a total of 1212 patients with an ejection fraction of 35% or less and coronary artery disease amenable to CABG were randomly assigned to medical therapy alone (602 patients) or medical therapy plus CABG (610 patients). The primary outcome was the rate of death from any cause. Major secondary outcomes included the rates of death from cardiovascular causes and of death from any cause or hospitalization for cardiovascular causes. RESULTS The primary outcome occurred in 244 patients (41%) in the medical-therapy group and 218 (36%) in the CABG group (hazard ratio with CABG, 0.86; 95% confidence interval [CI], 0.72 to 1.04; P=0.12). A total of 201 patients (33%) in the medical-therapy group and 168 (28%) in the CABG group died from an adjudicated cardiovascular cause (hazard ratio with CABG, 0.81; 95% CI, 0.66 to 1.00; P=0.05). Death from any cause or hospitalization for cardiovascular causes occurred in 411 patients (68%) in the medical-therapy group and 351 (58%) in the CABG group (hazard ratio with CABG, 0.74; 95% CI, 0.64 to 0.85; P<0.001). By the end of the follow-up period (median, 56 months), 100 patients in the medical-therapy group (17%) underwent CABG, and 555 patients in the CABG group (91%) underwent CABG. CONCLUSIONS In this randomized trial, there was no significant difference between medical therapy alone and medical therapy plus CABG with respect to the primary end point of death from any cause. Patients assigned to CABG, as compared with those assigned to medical therapy alone, had lower rates of death from cardiovascular causes and of death from any cause or hospitalization for cardiovascular causes. (Funded by the National Heart, Lung, and Blood Institute and Abbott Laboratories; STICH ClinicalTrials.gov number, NCT00023595.).

Insights from the STICH trial: change in left ventricular size after coronary artery bypass grafting with and without surgical ventricular reconstruction.

OBJECTIVE The present analysis of the Surgical Treatment for Ischemic Heart Failure randomized trial data examined the left ventricular volumes at baseline and 4 months after surgery to determine whether any magnitude of postoperative reduction in end-systolic volume affected survival after coronary artery bypass grafting alone compared with bypass grafting plus surgical ventricular reconstruction. METHODS Of the 1000 patients randomized, 555 underwent an operation and had a paired imaging assessment with the same modality at baseline and 4 months postoperatively. Of the remaining 455 patients, 424 either died before the 4-month study or did not have paired imaging tests and were excluded, and 21 were not considered because they had died before surgery or did not receive surgery. RESULTS Surgical ventricular reconstruction resulted in improved survival compared with coronary artery bypass grafting alone when the postoperative end-systolic volume index was 70 mL/m(2) or less. However, the opposite was true for patients achieving a postoperative volume index greater than 70 mL/m(2). A reduction in the end-systolic volume index of 30% or more compared with baseline was an infrequent event in both treatment groups and did not produce a statistically significant survival benefit with ventricular reconstruction. CONCLUSIONS In patients undergoing coronary artery bypass grafting plus surgical ventricular reconstruction, a survival benefit was realized compared with bypass alone, with the achievement of a postoperative end-systolic volume index of 70 mL/m(2) or less. Extensive ventricular remodeling at baseline might limit the ability of ventricular reconstruction to achieve a sufficient reduction in volume and clinical benefit.

Preoperative atrial fibrillation decreases event-free survival following cardiac surgery

OBJECTIVE To investigate the relationship between preoperative atrial fibrillation and early and late clinical outcomes following cardiac surgery. METHODS A retrospective cohort including all consecutive coronary artery bypass graft and/or valve surgery patients between 1995 and 2005 was identified (n = 9796). No patient had a concomitant surgical AF ablation. The association between preoperative atrial fibrillation and in-hospital outcomes was examined. We also determined late death and cardiovascular-related re-hospitalization by linking to administrative health databases. Median follow-up was 2.9 years (maximum 11 years). RESULTS The prevalence of preoperative atrial fibrillation was 11.3% (n = 1105), ranging from 7.2% in isolated CABG to 30% in valve surgery. In-hospital mortality, stroke, and renal failure were more common in atrial fibrillation patients (all p < 0.0001), although the association between atrial fibrillation and mortality was not statistically significant in multivariate logistic regression. Longitudinal analyses showed that preoperative atrial fibrillation was associated with decreased event-free survival (adjusted hazard ratio 1.55, 95% confidence interval 1.42-1.70, p < 0.0001). CONCLUSIONS Preoperative atrial fibrillation is associated with increased late mortality and recurrent cardiovascular events post-cardiac surgery. Effective management strategies for atrial fibrillation need to be explored and may provide an opportunity to improve the long-term outcomes of cardiac surgical patients.

Impact of Preoperative Angiotensin-Converting Enzyme Inhibitor Use on Clinical Outcomes After Cardiac Surgery

BACKGROUND Controversy exists about whether preoperative angiotensin-converting enzyme inhibitor (ACEi) therapy is associated with adverse outcomes after coronary artery bypass grafting (CABG). METHODS We analyzed the outcomes of consecutive patients who underwent isolated CABG between 1998 and 2007 at a single institution. We used multivariable models to examine the association between preoperative ACEi therapy and in-hospital and long-term outcomes. RESULTS Of the 5946 patients undergoing isolated CABG during the study period, 3,262 (54.9%) were treated with an ACEi preoperatively and 2,684 (45.1%) were not. Median follow-up was 3.8 years. Patients treated with an ACEi preoperatively were more likely to have diabetes, hypertension, an ejection fraction of less than 40%, and recent myocardial infarction (all p<0.0001). They were less likely to have pre-existing renal failure (p=0.004) or require an urgent or emergent CABG (p=0.03). Postoperative use of an inotrope (26% vs 20%, p<0.0001) or intra-aortic balloon pump (1.8% vs 1.1%, p=0.03) was more frequent in patients treated preoperatively with an ACEi; however, preoperative ACEi use was not an independent predictor of in-hospital mortality (odds ratio [OR], 1.1; p=0.76), prolonged length of stay in the intensive care unit (OR, 0.9; p=0.09), or new-onset renal failure (OR, 0.7; p=0.09). Furthermore, preoperative use of an ACEi had no independent association with long-term survival (p=0.54) or freedom from acute coronary syndrome (p=0.07). However, it was associated with an increased risk of readmission for heart failure over time (hazard ratio, 1.2; p=0.007). CONCLUSIONS We found no association between preoperative ACEi therapy and adverse in-hospital outcomes or long-term survival after CABG. Preoperative ACEi therapy appears to be safe in patients undergoing CABG.

Ten-Year Outcomes After Coronary Artery Bypass Grafting According to Age in Patients With Heart Failure and Left Ventricular Systolic Dysfunction: An Analysis of the Extended Follow-Up of the STICH Trial (Surgical Treatment for Ischemic Heart Failure).

Background: Advancing age is associated with a greater prevalence of coronary artery disease in heart failure with reduced ejection fraction and with a higher risk of complications after coronary artery bypass grafting (CABG). Whether the efficacy of CABG compared with medical therapy (MED) in patients with heart failure caused by ischemic cardiomyopathy is the same in patients of different ages is unknown. Methods: A total of 1212 patients (median follow-up, 9.8 years) with ejection fraction ⩽35% and coronary disease amenable to CABG were randomized to CABG or MED in the STICH trial (Surgical Treatment for Ischemic Heart Failure). Results: Mean age at trial entry was 60 years; 12% were women; 36% were nonwhite; and the baseline ejection fraction was 28%. For the present analyses, patients were categorized by age quartiles: quartile 1, ⩽54 years; quartile, 2 >54 and ⩽60 years; quartile 3, >60 and ⩽67 years; and quartile 4, >67 years. Older versus younger patients had more comorbidities. All-cause mortality was higher in older compared with younger patients assigned to MED (79% versus 60% for quartiles 4 and 1, respectively; log-rank P=0.005) and CABG (68% versus 48% for quartiles 4 and 1, respectively; log-rank P<0.001). In contrast, cardiovascular mortality was not statistically significantly different across the spectrum of age in the MED group (53% versus 49% for quartiles 4 and 1, respectively; log-rank P=0.388) or CABG group (39% versus 35% for quartiles 4 and 1, respectively; log-rank P=0.103). Cardiovascular deaths accounted for a greater proportion of deaths in the youngest versus oldest quartile (79% versus 62%). The effect of CABG versus MED on all-cause mortality tended to diminish with increasing age (Pinteraction=0.062), whereas the benefit of CABG on cardiovascular mortality was consistent over all ages (Pinteraction=0.307). There was a greater reduction in all-cause mortality or cardiovascular hospitalization with CABG versus MED in younger compared with older patients (Pinteraction=0.004). In the CABG group, cardiopulmonary bypass time or days in intensive care did not differ for older versus younger patients. Conclusions: CABG added to MED has a more substantial benefit on all-cause mortality and the combination of all-cause mortality and cardiovascular hospitalization in younger compared with older patients. CABG added to MED has a consistent beneficial effect on cardiovascular mortality regardless of age. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00023595.

Impact of admission serum glucose level on in-hospital outcomes following coronary artery bypass grafting surgery

OBJECTIVE The impact of admission serum glucose (SG) level on outcomes in coronary artery bypass grafting (CABG) surgery is unknown. The present study sought to determine whether elevated admission SG level is associated with adverse outcomes following CABG surgery. METHODS Patients undergoing CABG surgery between January 2000 and December 2005 at a single centre were identified (n=2856). Admission SG levels of less than 9.2 mmol/L and 9.2 mmol/L or greater were chosen to divide patients into two groups based on the 75th percentile of SG distribution. A logistic regression model was generated to determine the impact of admission SG level on a composite outcome of any one or more of in-hospital mortality, stroke, perioperative myocardial infarction, sepsis, deep sternal wound infection, renal failure, requirement for postoperative inotropes and prolonged ventilation. RESULTS In total, 76.3% of patients had an admission SG level of less than 9.2 mmol/L (group A) and 23.7% had an admission SG level of 9.2 mmol/L or greater (group B). Group B patients were more likely to be female, have diabetes, have preoperative renal failure, have an ejection fraction of less than 40%, experience myocardial infarction within 21 days before surgery, and have triple vessel or left main disease (P<0.05). Univariate analysis revealed no difference in in-hospital mortality between group A (2.2%) and group B (3.2%) (P=0.12); however, the composite outcome was more likely to occur in group B (40.8%) versus group A (27.9%) (P=0.0001). After multivariable adjustment, admission SG level of 9.2 mmol/L or greater remained an independent predictor of composite outcome (OR=1.3, 95% CI 1.0 to 1.7, P=0.02, receiver operating characteristic = 78%). CONCLUSION Admission SG level of 9.2 mmol/L or greater is associated with significant morbidity in patients undergoing CABG surgery.

Angiographic coronary diffuseness and outcomes in dialysis patients undergoing coronary artery bypass grafting surgery

OBJECTIVE Pre-operative dialysis-dependent renal failure (DDRF) is a predictor of morbidity and mortality following coronary artery bypass grafting surgery (CABG). Whether this is due in part to a more diffuse coronary atherosclerotic burden in these patients is unknown. The purpose of this study was to compare coronary atherosclerotic disease burden in patients with and without pre-existing DDRF undergoing CABG. METHODS From a retrospective analysis of a single-centre cardiac surgical database, consecutive DDRF patients undergoing isolated CABG (n=35) were matched to 70 non-dialysis-dependent (NDD) patients without renal failure by procedure, age, sex, functional status, ejection fraction, number of diseased vessels, and diabetes. Pre-operative angiograms were analyzed by a single, blinded adjudicator using a modification of a previously published coronary diffuseness score (range: 0-45). Angiographic scores and baseline and outcome characteristics were compared using chi(2) tests, Fishers Exact tests, and t-tests as appropriate. RESULTS No statistical differences were found among pre-operative characteristics between the two groups. The mean angiographic coronary diffuseness scores for the dialysis and non-dialysis groups were 18.2 and 20.6, respectively (p=0.13). Transfusion was more frequent (77 vs. 23%, p<0.0001) and median length of stay longer (9 vs. 7 days, p=0.02) in the DDRF group. There were no differences in the number of distal anastomoses performed in the two groups. Low rates of peri-operative myocardial infarction, stroke, re-operation, and in-hospital mortality were observed in both groups. CONCLUSIONS Objective quantification revealed that patients with DDRF undergoing CABG did not have a greater coronary artery atherosclerosis disease burden than matched controls who did not have pre-operative DDRF. This may be due to pre-operative patient selection bias. The increased morbidity and mortality of CABG in patients with DDRF is more likely to be due to the multiple adverse systemic effects of renal failure and dialysis on the cardiovascular system as opposed to diffuseness of distal coronary disease.

The impact of sequential grafting on clinical outcomes following coronary artery bypass grafting

OBJECTIVES Sequential anastomoses in coronary artery bypass grafting (CABG) offer theoretical advantages including increased graft flow and more complete revascularisation. However, published studies concerning the safety and efficacy of this technique are not definitive. The objective of this study was to assess the effect of sequential anastomoses on outcomes following CABG. METHODS Perioperative data were prospectively collected on all patients with triple-vessel disease who underwent first-time, isolated, on-pump CABG between 1995 and 2005 at a single centre. Patients with a left internal mammary artery graft to the anterior wall and saphenous vein grafts to the lateral and posterior walls were included. RESULTS Compared to patients without sequential anastomoses (n=1108), patients with sequential anastomoses (n=1246) were more likely to have an ejection fraction (EF)<40% (14.9% vs 10.8%, p=0.004), a recent myocardial infarction (19.3% vs 14.3%, p=0.001) and an urgent/emergent operative status (19.6% vs 14.4%, p=0.0008). Median follow-up was 78 months. After adjusting for clinical covariates, sequential grafting was not an independent predictor of in-hospital adverse events (odds ratio (OR) 1.15, 95% confidence interval (CI) 0.88-1.50, p=0.31) or long-term mortality and/or readmission to hospital (hazard ratio (HR) 0.98, 95% CI 0.86-1.12, p=0.74). Sequential grafting was an independent predictor of receiving greater than three distal anastomoses (OR 9.26, 95% CI; 6.27-13.67, p<0.0001). CONCLUSIONS Patients undergoing sequential grafting presented with greater acuity and worse systolic function. After adjusting for baseline differences, sequential grafting was not found to be an independent predictor of adverse events. These results support the safety of sequential anastomoses in patients undergoing CABG.

Simple Techniques to Manage the Patent Internal Mammary Artery in Redo Cardiac Surgery

The presence of a patent internal mammary artery (IMA) represents a well-known technical challenge in redo cardiac surgery. Dissection of the IMA and controlling its flow during cardioplegic delivery has thus been considered essential steps. This maneuver however, is associated with the risk of damaging the IMA. Herein, we report a technique, which involves no attempts to dissect, or clamp the IMA in 44 consecutive redo cardiac surgery procedures. The results demonstrate that this technique is simple, safe, and reduces the chance of IMA injury.