Kinetic analysis of cardiac troponin I release is no more accurate than a single 24-h measurement in predicting in-hospital outcome after cardiac surgery:

Myocardial protection in cardiac surgery: a comprehensive review of current therapies and future cardioprotective strategies

Cardiac surgery with cardiopulmonary bypass results in global myocardial ischemia-reperfusion injury, leading to significant postoperative morbidity and mortality. Although cardioplegia is the cornerstone of intraoperative cardioprotection, a number of additional strategies have been identified. The concept of preconditioning and postconditioning, despite its limited direct clinical application, provided an essential contribution to the understanding of myocardial injury and organ protection. Therefore, physicians can use different tools to limit perioperative myocardial injury. These include the choice of anesthetic agents, remote ischemic preconditioning, tight glycemic control, optimization of respiratory parameters during the aortic unclamping phase to limit reperfusion injury, appropriate choice of monitoring to optimize hemodynamic parameters and limit perioperative use of catecholamines, and early reintroduction of cardioprotective agents in the postoperative period. Appropriate management before, during, and after cardiopulmonary bypass will help to decrease myocardial damage. This review aimed to highlight the current advancements in cardioprotection and their potential applications during cardiac surgery.

THAP11 down-regulation may contribute to cardio-protective effects of sevoflurane anesthesia: Evidence from clinical and molecular evidence

This study aimed to explore the potential target of the cardio-protective effect induced by sevoflurane anesthesia based on evidence from clinical samples and in vitro model. Forty patients undergoing mitral valve replacement were randomly allocated to receive sevoflurane or propofol-based anesthesia. Atrial muscle specimens were collected from all patients, of which 5 were used to perform transcriptomics analysis. The cTn-I concentration was tested before, at the end of, and 24 h after surgery. In in vitro study, the expression level of the identified target gene, i.e., THAP11, was studied in H9C2 cells treated with sevoflurane or propofol. Then, we studied cell viability using CCK-8 staining, apoptosis by using flow cytometry, and cell death by lactic acid dehydrogenase (LDH) detection in H9C2 cells exposed to oxygen glucose deprivation/reoxygenation (OGD/R) injury. THAP11 was the most significantly down-regulated gene in the transcriptomics analysis (P < 0.001), as confirmed in validation samples (P = 0.006). THAP11 mRNA levels in atrial muscle specimens were positively associated with cTn-I levels at 24-h postoperatively (determination coefficient = 0.564; P < 0.001). Sevoflurane treatment down-regulated THAP11 in H9C2 cell models, which promoted cell viability, inhibited cell apoptosis, and death in the OGD/R injury cell model. Up-regulation of THAP11 reduced the protective effect of sevoflurane treatment against OGD/R injury. Sevoflurane anesthesia down-regulates the expression of THAP11, which contributes to a cardio-protective effect. THAP11 down-regulation promotes cell viability, and inhibits cell apoptosis and death, thereby protecting again myocardial injury; it may therefore be a novel target for perioperative cardio-protection.

Postoperative Cardiac Troponin I Thresholds Associated With 1-Year Cardiac Mortality After Adult Cardiac Surgery: An Attempt to Link Risk Stratification With Management Stratification in an Observational Study

OBJECTIVES

Cardiac troponin (cTn) concentrations are measured routinely in some centers after cardiac surgery as part of risk stratification, but there are no data on how increased cTn concentrations could change patients' management. The aim of this study was to estimate relevant cTnI thresholds and identify potential interventions (additional monitoring/therapeutic interventions) that could be part of management changes of patients with cTnI greater than relevant thresholds.

DESIGN

Retrospective, single-center, observational study.

SETTING

Bichat-Claude Bernard Hospital, Paris, France, between January 1, 2009, and December 31, 2012.

PARTICIPANTS

Consecutive adult patients undergoing cardiac surgery.

MEASUREMENTS AND MAIN RESULTS

cTnI was measured on the 20th postoperative hour. Causes of death and possible interventions were determined by analysis of individual medical records. cTnI thresholds for 1-year cardiac mortality with a specificity >80% were calculated. For this study, 3,228 procedures were analyzed; 129 deaths occurred (4%), 83 of which (2.6%) were cardiac deaths. Threshold cTnI values were 4.2 µg/L for coronary artery bypass grafting (95% confidence interval [CI] 3.9-4.5) and 10.7 µg/L for non-coronary artery bypass grafting (95% CI 10.0-11.3). In multivariable analysis, the EuroSCORE II (odds ratio 1.1 [95% CI 1.06-1.13]; p < 0.001) and cTnI concentrations greater than the thresholds (odds ratio 5.62 [95% CI 3.37-9.37]; p < 0.001) were associated with significantly increased risk of death. The additive and absolute Net Reclassification Index were 0.288% and 14.1%, respectively, for a logistic model including cTnI and EuroSCORE II (area under the curve C-index 0.82 [95% CI 0.77-0.87]) compared with a model including only EuroSCORE II (area under the curve C-index 0.80 [95% CI 0.75-0.84]). Fifty-three of the 83 patients who experienced cardiac death (64%) had a cTnI concentration greater than the threshold, and an intervention was deemed possible in 47 of those 53 (89%) (mostly patients with mild postoperative cardiac dysfunction). For noncardiac deaths, 28% of patients had a cTnI concentration greater than the threshold and no interventions were deemed possible.

CONCLUSIONS

In an attempt to evolve from risk to management stratification, this study's results identified a subgroup of patients with mild cardiac dysfunction and a cTnI concentration greater than the threshold who could be the target for interventions in future validation studies concerning changes in patient management.

Association of Troponin Trends and Cardiac Morbidity and Mortality After On-Pump Cardiac Surgery

BACKGROUND

Elevated, single-measure, postoperative troponin is associated with adverse events after cardiac surgery. We hypothesized that increases in troponin from the first to the second postoperative day are also associated with all-cause, 12-month mortality and major adverse cardiac events (MACE).

METHODS

This observational study included consecutive adults undergoing on-pump cardiac surgery with cardiac arrest. Troponin T was measured on the first and second postoperative day and was classified as "increasing" (>10%), "unchanged" (10% to -10%), or "decreasing" (<-10%). The primary endpoint was all-cause, 12-month mortality. Secondary endpoints were all-cause 12-month mortality or MACE and both outcomes at 30 days. The main analysis was by multivariable Cox regression.

RESULTS

Of 1,417 included patients, 99 (7.0%) died and 162 (11.4%) died or suffered MACE at 12 months. A significant interaction (p < 0.001) between first postoperative day troponin and the troponin trend from the first to the second postoperative day on 12-month, all-cause mortality precluded an analysis independent of first postoperative day troponin. Consequently, we stratified patients by their first postoperative day troponin (cutoff, 0.8 μg/L). Increasing troponin was associated with higher mortality in patients with first postoperative day troponin T ≥ 0.8 μg/L (hazard ratio, 1.98; 95% CI, 1.09 to 3.59; p = 0.025).

CONCLUSIONS

Troponin changes from the first to the second postoperative day should not be interpreted without consideration of the first postoperative day troponin concentration. For patients with a first postoperative day troponin ≥ 0.8 μg/L, an increase by more than 10% from the first to the second postoperative day was significantly associated with all-cause, 12-month mortality and other adverse events.

Rationale and design of the multicenter randomized trial investigating the effects of levosimendan pretreatment in patients with low ejection fraction (≤40 %) undergoing CABG with cardiopulmonary bypass (LICORN study)

Background

Patients with a left ventricular ejection fraction (LVEF) of less than 40 % are at high risk of developing postoperative low cardiac output syndrome (LCOS). Despite actual treatments (inotropic agents and/or mechanical assist devices), the mortality rate of such patients remains very high (13 to 24 %). The LICORN trial aims at assessing the efficacy of a preoperative infusion of levosimendan in reducing postoperative LCOS in patients with poor LVEF undergoing coronary artery bypass grafting (CABG).

Methods/Design

LICORN study is a multicenter, randomized double-blind, placebo-controlled trial in parallel groups. 340 patients with LVEF ≤40 %, undergoing CABG will be recruited from 13 French hospitals. The study drug will be started after anaesthesia induction and infused over 24 h (0.1 μg/kg/min).

The primary outcome (postoperative LCOS) is evaluated using a composite criterion composed of: 1) need for inotropic agents beyond 24 h following discontinuation of the study drug; 2) need for post-operative mechanical assist devices or failure to wean from these techniques when inserted pre-operatively; 3) need for renal replacement therapy. Secondary outcomes include: 1) mortality at Day 28 and Day 180; 2) each item of the composite criterion of the primary outcome; 3) the number of “ventilator-free” days and “out of intensive care unit” days at Day 28.

Discussion

The usefulness of levosimendan in the perioperative period has not yet been documented with a high level of evidence. The LICORN study is the first randomized controlled trial evaluating the clinical value of preoperative levosimendan in high risk cardiac surgical patients undergoing CABG.

Trial registration number

NCT02184819 (ClinicalTrials.gov).

A pilot study investigating the effects of remote ischemic preconditioning in high-risk cardiac surgery using a randomised controlled double-blind protocol

The efficacy of remote ischemic preconditioning (RIPC) in high-risk cardiac surgery is uncertain. In this study, 96 adults undergoing high-risk cardiac surgery were randomised to RIPC (3 cycles of 5 min of upper-limb ischemia induced by inflating a blood pressure cuff to 200 mmHg with 5 min of reperfusion) or control. Main endpoints were plasma high-sensitivity troponin T (hsTNT) levels at 6 and 12 h, worst post-operative acute kidney injury (AKI) based on RIFLE criteria, and noradrenaline duration. hsTNT levels were log-normally distributed and higher with RIPC than control at 6-h post cross-clamp removal [810 ng/ml (IQR 527-1,724) vs. 634 ng/ml (429-1,012); ratio of means 1.41 (99.17% CI 0.92-2.17); P=0.04] and 12 h [742 ng/ml (IQR 427-1,700) vs. 514 ng/ml (IQR 356-833); ratio of means 1.56 (99.17% CI 0.97-2.53); P=0.01]. After adjustment for baseline confounders, the ratio of means of hsTNT at 6 h was 1.23 (99.17% CI 0.88-1.72; P=0.10) and at 12 h was 1.30 (99.17% CI 0.92-1.84; P=0.05). In the RIPC group, 35/48 (72.9%) had no AKI, 5/48 (10.4%) had AKI risk, and 8/48 (16.7%) had either renal injury or failure compared to the control group where 34/48 (70.8%) had no AKI, 7/48 (14.6%) had AKI risk, and 7/48 (14.6%) had renal injury or failure (Chi-squared 0.41; two degrees of freedom; P = 0.82). RIPC increased post-operative duration of noradrenaline support [21 h (IQR 7-45) vs. 9 h (IQR 3-19); ratio of means 1.70 (99.17% CI 0.86-3.34); P=0.04]. RIPC does not reduce hsTNT, AKI, or ICU-support requirements in high-risk cardiac surgery.

[Cardiac biomarkers in perioperative risk stratification]

OBJECTIVES

The field of new cardiac biomarkers has triggered physicians' enthusiasm because of their potential diagnostic and prognostic values for routine clinical practice in the surgical setting. The objective of the present article is to review the role of new cardiac biomarkers and their potential additive clinical value in predicting short- and long-term risk following cardiac and non-cardiac surgery.

DATA SOURCES

A PubMed(®) database research in English and French languages published until June 2010. Keywords were cardiac biomarkers, troponins, cardiac troponin I (cTnI), natriuretic peptides, B-type natriuretic peptide (BNP), C-reactive protein (CRP), multiple markers approach, risk stratification, clinical risk scores.

DATA SYNTHESIS

Numerous publications deal with the diagnostic and prognostic values of new cardiac biomarkers in cardiac and non-cardiac surgical settings and provide an increasing evidence of their interest, validating different hierarchical steps which are mandatory before recommending a wide use of biomarkers for routine practice. Even if the first studies demonstrating an additional prognostic value of serum postoperative cTnI and/or preoperative BNP when compared with clinical predictive models are now available, we still lack data concerning an actual positive impact of new biomarkers measurements on clinical decision making or practice, as well as patient care and outcome.

CONCLUSIONS

While use of new cardiac biomarkers in the perioperative period appears to be a simple and objective tool for risk stratification at the bedside, we still need to remain cautious concerning their additional clinical value on existing predictive models for routine practice.

Biochemical injury markers and mortality after coronary artery bypass grafting: a systematic review

The strength of the association between cardiac biomarker release and prognosis is uncertain. We performed a systematic literature search to find articles regarding these markers and death after coronary surgical interventions, and evaluated the results with meta-analytic methods. We found 23 articles concerning 29,483 patients that reported the MB fraction of creatine kinase (CK-MB) and troponin T and I. Heterogeneity of existing studies prevented the pooling of the results of troponin studies. The pooled data of the CK-MB studies suggest that after coronary artery bypass grafting, CK-MB release of more than five to eight times the upper limit of the reference range is associated with an increased risk of death during the next 40 months.