Michael Yii

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.).

Age of Transfused Red Cells and Early Outcomes After Cardiac Surgery

BACKGROUND Red blood cells (RBC) undergo many changes during storage. Such changes are associated with reduced oxygen-carrying capacity and transfusion-related inflammatory reactions. The clinical significance of these changes in the cardiac surgical setting is unclear. This observational cohort study investigates the association between age of transfused RBC and early outcomes after cardiac surgery. METHODS The cardiac surgery database at St. Vincents Hospital Melbourne was cross-referenced with the Blood Transfusion Services database. In all, 670 consecutive patients who had nonemergency coronary artery bypass grafting or aortic valve replacement, or both, between June 2001 and June 2007 and had at least 2 RBC units transfused were studied. The storage variables studied were mean age of RBC, age of oldest RBC unit transfused, and transfusion of RBC stored longer than 30 days. Age of transfused blood was analyzed using logistic and linear regression analysis to determine an independent association with clinical outcomes: postoperative early mortality, renal failure, pneumonia, intensive care unit stay, and ventilation hours. Patient preoperative risk profile (EuroSCORE) and total number of RBC units transfused were adjusted for. RESULTS The storage age of RBC was not independently associated with any of the endpoints studied. The total quantity of RBC transfused was significantly associated with all studied endpoints. CONCLUSIONS Under current transfusion practice, the age of transfused RBC is not associated with early mortality and morbidity after cardiac surgery.

Contemporary Results Show Repeat Coronary Artery Bypass Grafting Remains a Risk Factor for Operative Mortality

BACKGROUND Reoperative coronary artery bypass grafting (redo CABG) shows improving outcomes, but with varying degrees of improvement. We assessed contemporary outcomes after redo CABG to determine if redo status is still a risk factor for early postoperative complications and midterm survival. METHODS Isolated CABG procedures (June 1, 2001 to May 31, 2008) within the Australasian Society of Cardiac and Thoracic Surgeons Cardiac Surgery Database were included. Redo status as a predictor for early outcomes was assessed with logistic regression analysis. Midterm survival was determined from the National Death Index. Effect of redo status on midterm survival was assessed using a Cox proportional hazards model. RESULTS Inclusion criteria were met by 13,436 patients, and 458 (3.4%) underwent redo CABG. Operative mortality was 4.8% for redo CABG and 1.8% for first-time CABG (p < 0.001). After adjustment, redo status remained a predictor for operative mortality (odds ratio [OR], 2.1; 95% confidence interval [CI], 1.3 to 3.6), myocardial infarction (OR, 2.8; 95% CI, 1.6 to 6.0), and prolonged ventilation (OR, 1.5; 95% CI, 1.1 to 2.0). Unadjusted survival was lower for the redo CABG group vs the first-time CABG group at up to 6 years (p = 0.01, log-rank test. After adjusting for differences in patient variables, redo status was not a predictor of midterm survival (OR, 1.03; 95% CI, 0.78 to 1.35; p = 0.85). CONCLUSIONS Early postoperative outcomes of redo CABG are encouraging. Midterm survival is excellent; however, redo remains a significant risk factor for operative mortality in contemporary practice.

An Australian risk prediction model for 30-day mortality after isolated coronary artery bypass: The AusSCORE

OBJECTIVE Our objective was to identify risk factors associated with 30-day mortality after isolated coronary artery bypass grafting in the Australian context and to develop a preoperative model for 30-day mortality risk prediction. SUMMARY BACKGROUND DATA Preoperative risk associated with cardiac surgery can be ascertained through a variety of risk prediction models, none of which is specific to the Australian population. Recently, it was shown that the widely used EuroSCORE model validated poorly for an Australian cohort. Hence, a valid model is required to appropriately guide surgeons and patients in assessing preoperative risk. METHODS Data from the Australasian Society of Cardiac and Thoracic Surgeons database project was used. All patients undergoing isolated coronary artery bypass grafting between July 2001 and June 2005 were included for analysis. The data were divided into creation and validation sets. The data in the creation set was used to develop the model and then the model was validated in the validation set. Preoperative variables with a P value of less than .25 in chi(2) analysis were entered into multiple logistic regression analysis to develop a preoperative predictive model. Bootstrap and backward elimination methods were used to identify variables that are truly independent predictors of mortality, and 6 candidate models were identified. The Akaike Information Criteria (AIC) and prediction mean square error were used to select the final model (AusSCORE) from this group of candidate models. The AusSCORE model was then validated by average receiver operating characteristic, the P value for the Hosmer-Lemeshow goodness-of-fit test, and prediction mean square error obtained from n-fold validation. RESULTS Over the 4-year period, 11,823 patients underwent cardiac surgery, of whom 65.9% (7709) had isolated coronary bypass procedures. The 30-day mortality rate for this group was 1.74% (134/7709). Factors selected as independent predictors in the preoperative isolated coronary bypass AusSCORE model were as follows: age, New York Heart Association class, ejection fraction estimate, urgency of procedure, previous cardiac surgery, hypercholesterolemia (lipid-lowering treatment), peripheral vascular disease, and cardiogenic shock. The average area under the receiver operating characteristic was 0.834, the P value for the Hosmer-Lemeshow chi(2) test statistic was 0.2415, and the prediction mean square error was 0.01869. CONCLUSION We have developed a preoperative 30-day mortality risk prediction model for isolated coronary artery bypass grafting for the Australian cohort.

The association of blood transfusion with mortality after cardiac surgery: cause or confounding? (CME)

BACKGROUND: Bleeding into the chest is a life‐threatening complication of cardiac surgery. Blood transfusion has been implicated as an important cause of harm associated with bleeding, based largely on studies demonstrating an independent association between transfusion and mortality. These studies did not, however, consider the possibility that bleeding may in itself be harmful, inasmuch as drains are inefficient at clearing blood from the chest and retained blood may compromise cardiac and lung function.

Differences in Myocardial Structure and Coronary Microvasculature Between Men and Women With Coronary Artery Disease

Women younger than 75 years with stable angina or acute coronary syndrome have higher cardiac mortality than similarly aged men, despite less obstructive coronary artery disease. To determine whether the myocardial structure and coronary microvasculature of women differs from that of men, we performed histological analysis of biopsies from nonischemic left ventricular myocardium from 46 men and 11 women undergoing coronary artery bypass graft surgery who did not have previous cardiac surgery, myocardial infarction, heart failure, atrial fibrillation, or furosemide therapy. The 2 patient groups had similar clinical characteristics, apart from a lower body surface area (BSA) in women (P=0.0015). Women had less interstitial fibrosis than men (P=0.019) but similar perivascular fibrosis. Arteriolar wall area/circumference ratio, a measure of arteriolar wall thickness, was 47% greater in women than men (P=0.012). Cardiomyocyte width and diffusion radius were positively correlated, and capillary length density was negatively correlated with BSA (P<0.05). Whereas cardiomyocyte width, capillary length density, diffusion radius, and cardiomyocyte width/BSA ratio were similar for men and women, women had a greater diffusion radius/BSA ratio (P=0.0038) and a greater diffusion radius/cardiomyocyte width ratio (P=0.027). Women also had lower vascular endothelial growth factor (VEGF) receptor-1 levels (P=0.048) and VEGF receptor-1/VEGF-A ratio (P=0.024) in plasma. We conclude that women with extensive coronary artery disease have greater arteriolar wall thickness and diffusion radius relative to BSA and to cardiomyocyte width than men, which may predispose to myocardial ischemia. Additional studies of larger numbers of women with less extensive coronary artery disease are required to confirm these findings.

Clinical characteristics and early mortality of patients undergoing coronary artery bypass grafting compared to percutaneous coronary intervention: Insights from the Australasian Society of Cardiac and Thoracic Surgeons (ASCTS) and the Melbourne Interventional Group (MIG) Registries

OBJECTIVES Controversy continues over the optimal revascularisation strategy for patients with multi-vessel coronary artery disease. Clinical characteristics, risk profile, and mortality of patients undergoing coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) are thought to differ but there are limited contemporary comparative data. METHODS We compared clinical characteristics, in-hospital and 30-day mortality of 3841 consecutive patients undergoing isolated CABG and 4417 undergoing PCI. Independent predictors of 30-day mortality were determined by multiple logistic regression analysis. RESULTS CABG patients were older (p<0.01). The CABG group had a higher incidence of diabetes, heart failure, left ventricular ejection fraction <45%, multi-vessel coronary artery, peripheral vascular and cerebro-vascular disease (all p<0.01). Patients undergoing PCI had a higher incidence of recent myocardial infarction (MI) as the indication for revascularisation (p<0.01). In-hospital and 30-day mortality was 1.8% and 1.7% in the CABG group, and 1.4% and 1.8% in the PCI group, respectively. Independent predictors of 30-day mortality after CABG were age (odds ratio 1.1 per year, 95% confidence interval 1.0-1.1), cardiogenic shock (4.10, 1.7-10.5) and previous CABG (6.6, 2.4-17.7). Predictors after PCI were diabetes (2.7, 1.4-5.1), female gender (3.0, 1.6-5.5), renal failure (3.2, 1.2-8.0), MI<24h (4.0, 2.2-7.6), left main intervention (5.4, 1.0-27.7), heart failure (6.0, 2.6-14.0) and cardiogenic shock (11.7, 5.4-25.2). CONCLUSIONS In contemporary clinical practice, CABG is preferred in patients with multi-vessel coronary and associated non-coronary vascular disease, while PCI is the dominant strategy for acute MI. Despite this, in-hospital and 30-day mortality rates were similar. Predictors of early mortality after CABG differ to those of PCI.

Diastolic Dysfunction of Aging Is Independent of Myocardial Structure but Associated with Plasma Advanced Glycation End-Product Levels

Background Heart failure is associated with abnormalities of myocardial structure, and plasma levels of the advanced glycation end-product (AGE) Nε-(carboxymethyl)lysine (CML) correlate with the severity and prognosis of heart failure. Aging is associated with diastolic dysfunction and increased risk of heart failure, and we investigated the hypothesis that diastolic dysfunction of aging humans is associated with altered myocardial structure and plasma AGE levels. Methods We performed histological analysis of non-ischemic left ventricular myocardial biopsies and measured plasma levels of the AGEs CML and low molecular weight fluorophores (LMWFs) in 26 men undergoing coronary artery bypass graft surgery who had transthoracic echocardiography before surgery. None had previous cardiac surgery, myocardial infarction, atrial fibrillation, or heart failure. Results The patients were aged 43–78 years and increasing age was associated with echocardiographic indices of diastolic dysfunction, with higher mitral Doppler flow velocity A wave (r = 0.50, P = 0.02), lower mitral E/A wave ratio (r = 0.64, P = 0.001), longer mitral valve deceleration time (r = 0.42, P = 0.03) and lower early diastolic peak velocity of the mitral septal annulus, e’ (r = 0.55, P = 0.008). However, neither mitral E/A ratio nor mitral septal e’ was correlated with myocardial total, interstitial or perivascular fibrosis (picrosirius red), immunostaining for collagens I and III, CML, and receptor for AGEs (RAGE), cardiomyocyte width, capillary length density, diffusion radius or arteriolar dimensions. Plasma AGE levels were not associated with age. However, plasma CML levels were associated with E/A ratio (r = 0.44, P = 0.04) and e’ (r = 0.51, P = 0.02) and LMWF levels were associated with E/A ratio (r = 0.49, P = 0.02). Moreover, the mitral E/A ratio remained correlated with plasma LMWF levels in all patients (P = 0.04) and the mitral septal e’ remained correlated with plasma CML levels in non-diabetic patients (P = 0.007) when age was a covariate. Conclusions Diastolic dysfunction of aging was independent of myocardial structure but was associated with plasma AGE levels.

Validation of Euroscore model in an Australian patient population.

Background:  The purpose of the present paper was to assess the performance of the European system for cardiac operative risk evaluation (EuroSCORE) model in an Australian adult cardiac surgical population.

Combined Proximal Endografting With Distal Bare-Metal Stenting for Management of Aortic Dissection

BACKGROUND Established endovascular treatments for aortic dissection often result in incomplete aortic repair, potentially leading to late complications involving the distal aorta. To address the problems of incomplete true lumen reconstitution and late aneurysmal change, we report the midterm results of combined proximal endografting with distal true lumen bare-metal stenting (STABLE: Staged Total Aortic and Branch vesseL Endovascular reconstruction) in Stanford type A and B aortic dissection. METHODS Between January 2003 and January 2010, 31 patients underwent staged total aortic and branch vessel endovascular reconstruction for management of acute (type A, 13; type B, 11) and chronic (type B, 7) aortic dissection. Proximal endografting was combined with bare-metal Z stent implantation in the distal true lumen. Patients with type A dissection underwent adjunctive treatment at operation. Computed tomography angiography was performed at baseline, 1 year, and annually thereafter to assess aortic remodelling. RESULTS Primary technical success was 97%. Thirty-day rates of death, stroke, and permanent paraplegia/paresis were 3% (n=1), 0%, and 0%, respectively. Mean follow-up was 57.3 months (range, 5 to 100 months). Overall survival was 60% at 100 months. Aortic-specific survival was 93%. Four patients (13%) underwent device-related reintervention. One (3%) late aortic-related death occurred. Thoracic (p=0.64) and abdominal (p=0.14) aortic dimensions were stable. The true lumen index increased significantly at follow-up. CONCLUSIONS Staged total aortic and branch vessel endovascular reconstruction is a feasible ancillary endovascular technique to address the problems of distal true lumen collapse, incomplete aortic remodelling, and late aneurysm formation in aortic dissection.