Impaired calcium handling mechanisms in atrial trabeculae of diabetic patients.

The aim of this study was to investigate cardiomyocyte Ca2+ handling and contractile function in freshly excised human atrial tissue from diabetic and non-diabetic patients undergoing routine surgery. Multicellular trabeculae (283 ± 20 µm in diameter) were dissected from the endocardial surface of freshly obtained right atrial appendage samples from consenting surgical patients. Trabeculae were mounted in a force transducer at optimal length, electrically stimulated to contract, and loaded with fura-2/AM for intracellular Ca2+ measurements. The response to stimulation frequencies encompassing the physiological range was recorded at 37°C. Myofilament Ca2+ sensitivity was assessed from phase plots and high potassium contractures of force against [Ca2+ ]i . Trabeculae from diabetic patients (n = 12) had increased diastolic (resting) [Ca2+ ]i (p = 0.03) and reduced Ca2+ transient amplitude (p = 0.04) when compared to non-diabetic patients (n = 11), with no difference in the Ca2+ transient time course. Diastolic stress was increased (p = 0.008) in trabeculae from diabetic patients, and peak developed stress decreased (p ≤ 0.001), which were not accounted for by reduction in the cardiomyocyte, or contractile protein, content of trabeculae. Trabeculae from diabetic patients also displayed diminished myofilament Ca2+ sensitivity (p = 0.018) compared to non-diabetic patients. Our data provides evidence of impaired calcium handling during excitation-contraction coupling with resulting contractile dysfunction in atrial tissue from patients with type 2 diabetes in comparison to the non-diabetic. This highlights the importance of targeting cardiomyocyte Ca2+ homeostasis in developing more effective treatment options for diabetic heart disease in the future.

Comparison of contemporary risk scores for predicting outcomes after surgery for active infective endocarditis.

Decision making regarding surgery for acute bacterial endocarditis is complex given its heterogeneity and often fatal course. Few studies have investigated the utility of operative risk scores in this setting. Endocarditis-specific scores have recently been developed. We assessed the prognostic utility of contemporary risk scores for mortality and morbidity after endocarditis surgery. Additive and logistic EuroSCORE I, EuroSCORE II, additive Society of Thoracic Surgeon's (STS) Endocarditis Score and additive De Feo-Cotrufo Score were retrospectively calculated for patients undergoing surgery for endocarditis during 2005-2011. Pre-specified primary outcomes were operative mortality, composite morbidity and mortality during follow-up. A total of 146 patients were included with an operative mortality of 6.8 % followed for 4.1 ± 2.4 years. Mean scores were additive EuroSCORE I: 8.0 ± 2.5, logistic EuroSCORE I: 13.2 ± 10.1 %, EuroSCORE II: 9.1 % ± 9.4 %, STS Score: 32.2 ± 13.5 and De Feo-Cotrufo Score: 14.6 ± 9.2. Corresponding areas under curve (AUC) for operative mortality 0.653, 0.645, 0.656, 0.699 and 0.744; for composite morbidity were 0.623, 0.625, 0.720, 0.714 and 0.774; and long-term mortality 0.588, 0.579, 0.686, 0.735 and 0.751. The best tool for post-operative stroke was EuroSCORE II: AUC 0.837; for ventilation >24 h and return to theatre the De Feo-Cotrufo Scores were: AUC 0.821 and 0.712. Pre-operative inotrope or intra-aortic balloon pump treatment, previous coronary bypass grafting and dialysis were independent predictors of operative and long-term mortality. In conclusion, risk models developed specifically from endocarditis surgeries and incorporating endocarditis variables have improved prognostic ability of outcomes, and can play an important role in the decision making towards surgery for endocarditis.

Long-term survival after isolated tricuspid valve replacement.

BACKGROUND: Isolated replacement of the tricuspid valve is rare, and the decision to operate is difficult. This study reviews the in-hospital mortality and long-term survival after tricuspid valve replacement in the absence of concomitant left sided valve surgery. It identifies predictors of poor outcome. METHODS: All patients who underwent tricuspid valve replacement between January 1995 and December 2011 were retrospectively reviewed. Patients having concomitant mitral or aortic valve surgery were excluded. Logistic regression was used to identify predictors of early and late death. RESULTS: Twenty-nine cases were identified. There were six in-hospital deaths (20.6%), and eight late deaths. Ascites was associated with in-hospital death (hazard ratio 16.96; p=0.0052). Higher dose of Frusemide was associated with late mortality (hazard ratio 1.157 per 20mg increase; p=0.0155). Frusemide dose and ascites were both significantly associated with death overall (p<0.01). Survival analysis estimated a 50% probability of surviving to 12.45 years. CONCLUSIONS: Isolated tricuspid valve replacement has a high peri-operative risk. Long-term survival in this study was consistent with other reports. Ascites and higher doses of Frusemide were associated with poor outcomes.

Valvular repair or replacement for mitral endocarditis: 7-year cohort study.

BACKGROUND: A few studies have compared mitral valve repair and replacement in the setting of infective endocarditis, with varying results. We compared the characteristics and outcomes of mitral repair and replacement in endocarditis patients. METHODS: All patients undergoing mitral valve repair or replacement for active mitral endocarditis during 2005-2011 were included. Operative and follow-up mortality, composite morbidity, recurrent endocarditis, and redo operations were prespecified endpoints for analyses. RESULTS: There were 25 and 35 patients undergoing mitral valve repair and replacement, respectively. They were followed-up for 3.9 ± 2.5 years. Valve replacement patients were older (p = 0.029), had a higher prevalence of intracardiac abscess (p = 0.035), previous endocarditis (p = 0.036), atrial fibrillation (p = 0.001), worse renal function (p = 0.013), higher risk scores (p = 0.004-0.020), and longer operation times (p < 0.001). Repair and replacement had similar rates of operative mortality (4.0% vs. 8.6%, p = 0.634), composite morbidity (16.0% vs. 28.6%, p = 0.357), survival (p = 0.564), recurrent endocarditis (p = 0.081), and redo operations (p = 0.813). Independent predictors of operative mortality were preoperative inotropic or intraaortic balloon pump support. The independent predictor of mortality during follow-up was dialysis. Independent predictors of composite morbidity were intracardiac abscess and hypercholesterolemia. The independent predictor of recurrent endocarditis was previous endocarditis, and the independent predictor of redo operation was previous stroke. CONCLUSION: Mitral valve replacement candidates had more baseline risk factors and higher raw rates of postoperative mortality and morbidity, which did not reach statistical significance.

Diagnosis of MI after CABG with high-sensitivity troponin T and new ECG or echocardiogram changes: relationship with mortality and validation of the universal definition of MI.

AIMS: Criteria for diagnosing myocardial infarction (MI) after coronary artery bypass grafting (CABG) are controversial. Uncertainties remain around the optimal threshold for biomarker elevation and the need for associated criteria. There are no studies of high-sensitivity troponin (hs-TnT) after CABG. We assessed whether using hs-TnT to define MI after CABG was associated with 30-day and medium-term mortality and evaluated the utility of adding to the troponin criteria new Q-waves or imaging evidence of new wall motion abnormality as suggested in the Universal Definition of MI. METHODS: Isolated CABG was performed in 818 patients from July 2010 to June 2012 and hs-TnT was measured 12-24 hours after CABG. Patients with rising baseline or missing troponins (n=258) were excluded. Thresholds of 140 ng/l (10-times 99th percentile upper reference limit) and 500 ng/l (10-times coefficient of variation of 10% for fourth-generation troponin T applied to hs-TnT) were prespecified. RESULTS: Mean follow up was 1.8±0.6 years. On multivariate analyses, isolated hs-TnT rise >140 ng/l (n=360) or >500 ng/l (n=162) were not associated with mortality. Additional ECG and/or echocardiographic criteria plus hs-TnT >140 ng/l was associated with 30-day mortality (hazard ratio, HR, 4.92, 95% CI 1.34-18.1; p=0.017) and medium-term mortality (HR 3.44, 95% CI 1.13-10.5; p=0.030), whereas ECG and/or echocardiographic abnormalities with hs-TnT >500 ng/l was not (p=0.281 and p=0.123 for 30-day and medium-term mortality, respectively). CONCLUSIONS: A definition for MI following CABG using hs-TnT with a cut point of 10-times 99th percentile upper reference limit and ECG and/or echocardiographic criteria predicts 30-day and medium-term mortality. These findings validate the Third Universal Definition of type 5 MI.

Penetrating cardiac injury: overcoming the limits set by Nature.

Repair of cardiac wounds was considered impossible little over 100 years ago. Despite progress, penetrating cardiac injury remains a highly lethal form of trauma today. Cardiac tamponade and exsanguination are the greatest immediate and life-threatening risks. Clinical presentation is extremely variable and diagnosis may be highly deceptive. Unlike other forms of trauma, resuscitation is of limited value and urgent operative intervention is the only meaningful treatment. Refinements in cardiothoracic surgery and the simultaneous evolution of trauma care systems have both contributed to saving lives. However, mortality rates for this condition have changed little in the last century, due largely to the rising proportion of more lethal injuries caused by gunshot wounds.

Monitoring risk-adjusted outcomes in congenital heart surgery: does the appropriateness of a risk model change with time?

BACKGROUND: Risk adjustment of outcomes in pediatric congenital heart surgery is challenging due to the great diversity in diagnoses and procedures. We have previously shown that variable life-adjusted display (VLAD) charts provide an effective graphic display of risk-adjusted outcomes in this specialty. A question arises as to whether the risk model used remains appropriate over time. METHODS: We used a recently developed graphic technique to evaluate the performance of an existing risk model among those patients at a single center during 2000 to 2003 originally used in model development. We then compared the distribution of predicted risk among these patients with that among patients in 2004 to 2006. Finally, we constructed a VLAD chart of risk-adjusted outcomes for the latter period. RESULTS: Among 1083 patients between April 2000 and March 2003, the risk model performed well at predicted risks above 3%, underestimated mortality at 2% to 3% predicted risk, and overestimated mortality below 2% predicted risk. There was little difference in the distribution of predicted risk among these patients and among 903 patients between June 2004 and October 2006. Outcomes for the more recent period were appreciably better than those expected according to the risk model. This finding cannot be explained by any apparent bias in the risk model combined with changes in case-mix. CONCLUSIONS: Risk models can, and hopefully do, become out of date. There is scope for complacency in the risk-adjusted audit if the risk model used is not regularly recalibrated to reflect changing standards and expectations.

Does the Aristotle Score predict outcome in congenital heart surgery?

OBJECTIVE: The Aristotle Score has been proposed as a measure of 'complexity' in congenital heart surgery, and a tool for comparing performance amongst different centres. To date, however, it remains unvalidated. We examined whether the Basic Aristotle Score was a useful predictor of mortality following open-heart surgery, and compared it to the Risk Adjustment in Congenital Heart Surgery (RACHS-1) system. We also examined the ability of the Aristotle Score to measure performance. METHODS: The Basic Aristotle Score and RACHS-1 risk categories were assigned retrospectively to 1085 operations involving cardiopulmonary bypass in children less than 18 years of age. Multiple logistic regression analysis was used to determine the significance of the Aristotle Score and RACHS-1 category as independent predictors of in-hospital mortality. Operative performance was calculated using the Aristotle equation: performance = complexity x survival. RESULTS: Multiple logistic regression identified RACHS-1 category to be a powerful predictor of mortality (Wald 17.7, p < 0.0001), whereas Aristotle Score was only weakly associated with mortality (Wald 4.8, p = 0.03). Age at operation and bypass time were also highly significant predictors of postoperative death (Wald 13.7 and 33.8, respectively, p < 0.0001 for both). Operative performance was measured at 7.52 units. CONCLUSIONS: The Basic Aristotle Score was only weakly associated with postoperative mortality in this series. Operative performance appeared to be inflated by the fact that the overall complexity of cases was relatively high in this series. An alternative equation (performance = complexity/mortality) is proposed as a fairer and more logical method of risk-adjustment.

Quality assurance in congenital heart surgery.

OBJECTIVE: The aim of this study was to develop a graphical method of risk-stratified outcome analysis in paediatric cardiac surgery to provide a means of continuous, prospective performance monitoring and allow real-time detection of change in outcomes. METHODS: Risk-adjusted survival following open-heart surgery was prospectively measured over a 15-month period (n=460). Outcomes were charted using variable life-adjusted display (VLAD) charts, which indicate the cumulative difference in observed minus expected survival against the cumulative number of cases performed. Risk stratification was based on RACHS-1 (risk adjustment in congenital heart surgery) risk category and age at surgery, using our previously published risk model. The probability of deviation in performance from the expected baseline level was determined using a mathematical model. RESULTS: By the end of the series, observed survival (443/460=96.3%) exceeded that predicted by the risk model (434.5/460=94.5%), equivalent to a one-third reduction in expected mortality. Mathematical modelling indicated a 1-5% likelihood that this difference would have occurred by random variation alone, suggesting the outcomes represented genuine improvement. CONCLUSIONS: VLAD charts provide an effective, easily visualised display of surgical performance and can be applied to paediatric cardiac surgery. Early detection of change, whether improvement or deterioration, is important for ongoing quality assurance within a cardiac surgery programme.

Extending the boundaries of the primary arterial switch operation in patients with transposition of the great arteries and intact ventricular septum.

BACKGROUND: We have previously suggested that the primary arterial switch operation is a feasible strategy for patients with transposition of the great arteries and intact ventricular septum (TGA-IVS) up to age 2 months. This study reports our current results with this approach and examines whether this policy could be extended beyond age 2 months. METHODS AND RESULTS: 380 patients who underwent arterial switch for TGA-IVS were reviewed. 275 patients were younger than 3 weeks at the time of surgery (early switch group); 105 patients were 3 weeks or older (range, 21 to 185 days) (late switch group). There was no difference in outcome in terms of in-hospital mortality (5.5% versus 3.8%) or need for mechanical circulatory support (3.6% versus 5.7%) between early and late switch groups. However, duration of postoperative ventilation (4.9 versus 7.1 days, P=0.012) and length of postoperative stay (12.5 versus 18.9 days, P<0.001) were significantly prolonged in the late switch group. Primary left ventricular failure resulting in death occurred in 2 patients in the late switch group, with no deaths in 9 patients aged 2 to 6 months. CONCLUSIONS: This experience confirms that in TGA-IVS, the left ventricle maintains the potential for systemic work well beyond the first month of life. Consequently, neonates at high risk or late referrals can benefit from delayed arterial switch, even beyond age 2 months. However, the need for mechanical support in some of the older patients may limit the widespread adoption of such a strategy.

Risk stratification in paediatric open-heart surgery.

OBJECTIVE: The aims of this study were to identify independent risk factors for mortality following paediatric open-heart surgery and to develop risk models for use in clinical audit based on identified risk factors. The study also tests the validity of the recently proposed Risk Adjustment in Congenital Heart Surgery (RACHS-1) method of risk stratification as applied to open-heart operations. METHODS: A multiple logistic regression analysis was performed on all patients less than 18 years of age undergoing open-heart surgery at a single institution over a 3-year period. Preoperative and operative variables included for analysis were age at operation, weight, sex, American Society of Anaesthesiology (ASA) grade, RACHS-1 risk category, preoperative haemoglobin, bypass time, temperature, cross-clamp time, circulatory arrest time, blood transfusion on bypass and surgeon. The outcome measure was in-hospital death. RESULTS: 1085 consecutive open-heart cases were identified. There were 51 in-hospital deaths (4.7%). Variables identified as being independently significant risk factors for in-hospital death were age (P = 0.0002), RACHS-1 risk category (P < 0.0001), and bypass time. Based on these three variables, a risk model was constructed to predict mortality. The area under the receiver-operating-characteristic (ROC) curve for this model was 0.86. A second model was constructed ignoring bypass time. In this model, the significance of the 'preoperative' risk factors was (P = 0.0003) for age and (P < 0.0001), for RACHS-1 risk category. The area under the ROC curve was 0.81 for the second model. CONCLUSIONS: This study identifies age at operation, RACHS-1 risk category and bypass time as highly significant risk factors for mortality after paediatric open-heart surgery. It validates the RACHS-1 risk stratification method as applied to the subset of open-heart surgery, whilst accepting the limitations of such a system. The risk models formulated permit risk prediction and allow for analysis of surgical results. Such risk-adjustment is important when assessing performance and comparing outcomes amongst individuals or institutions.

Circulatory arrest for repair of postcoarctation site aneurysm.

BACKGROUND: Aneurysm at previous coarctation repair may be seen more frequently as children operated for this condition survive into adulthood. We use deep hypothermic circulatory arrest to repair these aneurysms. METHODS: A case series was conducted using 12-year, single-institution, retrospective chart review. RESULTS: Twenty-one patients underwent left thoracotomy and repair of aneurysm at the site of previous coarctation repair. Three cases presented emergently as aortobronchial fistulas. The age range was 16 to 73 years (median, 26 years). The median circulatory arrest time was 33 minutes (range, 22 to 55 minutes). Repair involved interposition graft replacement. Six patients required additional tube graft replacement of the left subclavian artery. There was 1 operative mortality in a patient having a hypoxic brain injury secondary to an anaphylactic reaction to a plasma expander. There were no embolic strokes or paraplegia. One patient had a recurrent laryngeal nerve paresis. There was 1 case of Horner's syndrome after subclavian artery replacement. CONCLUSIONS: Circulatory arrest allows for the accurate repair of this difficult pathologic process and avoids the risk of clamp-related injuries. Follow-up out to 16 years demonstrates this technique of repair to be durable, with no late deaths or reoperations for recurrent aneurysm.