Cardiac troponin I release after coronary artery bypass grafting operation: effects on operative and midterm survival

Elevated troponin I is associated with a worse long-term prognosis in patients undergoing beating-heart coronary surgery

OBJECTIVES

The impacts of elevated troponin I levels after coronary artery bypass grafting (CABG) on long-term outcomes were investigated.

METHODS

A total of 996 patients who underwent elective isolated CABG for stable or unstable angina were enrolled. Patients were divided into higher and lower groups based on 80th percentile postoperative peak troponin I (ppTnI) levels. The relationship between ppTnI and long-term clinical outcomes was analysed.

RESULTS

The median ppTnI was 1.55 (2.74) ng/ml and was significantly higher in the conventional CABG subgroup than in the beating-heart CABG subgroup: 4.04 (4.71) vs 1.24 (1.99) ng/ml, P < 0.001. The 80th percentile of ppTnI was 3.3 ng/ml in the beating-heart CABG subgroup and 8.9 ng/ml in the conventional CABG subgroup. In the conventional CABG subgroup (n = 150), 10-year overall survival showed no significant difference between the higher (≥8.9 ng/ml) and lower (<8.9 ng/ml) ppTnI groups: 71% (10%) vs 76% (5%), P = 0.316. However, the beating-heart CABG subgroup (n = 846) showed significantly worse 10-year overall survival in the higher ppTnI group (≥3.3 ng/ml) than in the lower ppTnI group (<3.3 ng/ml): 64% (6%) vs 73% (3%), P = 0.010. In the beating-heart CABG subgroup, multivariable analysis showed that ppTnI exceeding the 80th percentile was a risk factor for overall death (hazard ratio: 1.505, 95% confidence interval: 1.019-2.225, P = 0.040).

CONCLUSIONS

Higher ppTnI over the 80th percentile was associated with worse long-term survival in beating-heart CABG, but not in conventional CABG.

Plasma exosomes characterization reveals a perioperative protein signature in older patients undergoing different types of on-pump cardiac surgery

Although exosomes are extracellular nanovesicles mainly involved in cardioprotection, it is not known whether plasma exosomes of older patients undergoing different types of on-pump cardiac surgery protect cardiomyocytes from apoptosis. Since different exosomal proteins confer pro-survival effects, we have analyzed the protein cargo of exosomes circulating early after aortic unclamping. Plasma exosomes and serum cardiac troponin I levels were measured in older cardiac surgery patients (NYHA II-III) who underwent first-time on-pump coronary artery bypass graft (CABG; n = 15) or minimally invasive heart valve surgery (mitral valve repair, n = 15; aortic valve replacement, n = 15) at induction of anesthesia (T0, baseline), 3 h (T1) and 72 h (T2) after aortic unclamping. Anti-apoptotic role of exosomes was assessed in HL-1 cardiomyocytes exposed to hypoxia/re-oxygenation (H/R) by TUNEL assay. Protein exosomal cargo was characterized by mass spectrometry approach. Exosome levels increased at T1 (P < 0.01) in accord with troponin values in all groups. In CABG group, plasma exosomes further increased at T2 (P < 0.01) whereas troponin levels decreased. In vitro, all T1-exosomes prevented H/R-induced apoptosis. A total of 340 exosomal proteins were identified in all groups, yet 10% of those proteins were unique for each surgery type. In particular, 22 and 12 pro-survival proteins were detected in T1-exosomes of heart valve surgery and CABG patients, respectively. Our results suggest that endogenous intraoperative cardioprotection in older cardiac surgery patients is early mediated by distinct exosomal proteins regardless of surgery type.

Perioperative myocardial infarction diagnosis after coronary artery bypass grafting surgery using coupled electrocardiographic changes and cardiac troponin I

Purpose

Perioperative myocardial infarction (PMI) is one of the most common causes of prolonged intensive care unit (ICU) and hospital stay after coronary artery bypass grafting (CABG) and is associated with poor prognosis and increases postoperative mortality due to the lack of accurate diagnostic methods. This study examines the association between electrocardiography (ECG) ischemic changes and cardiac troponin I concentration.

Methods

In this cross-sectional study, the ECG of 100 patients was recorded before and 24 h after the surgery. The cardiac troponin I concentration was measured 24 h after the termination of the surgery.

Results

The average concentration of troponin I was 6.79 μg/L in the no-ECG-changes group, 11.69 μg/L in the ST depression group, 11.26 μg/L in the ST elevation group, and 27.54 μg/L in the new Q wave group. The mean troponin concentration was significantly higher in the ECG-changes group compared to no-ECG-changes group. Comparing the ECG-changes together showed significant differences between the new Q wave and the other changes. ST elevation and ST depression were not statistically significant.

Conclusion

The three ECG-changes groups had a higher risk of PMI after their CABG. The risk of PMI was at its highest value in the new Q wave group and at its lowest in the no-ECG-changes group.

Cardiac troponin I and creatine kinase-MB release after different cardiac surgeries

AIMS

To conduct a comparative study of cardiac troponin I (cTnI) and MB isoenzyme of serum creatine kinase (CK-MB) after different cardiac surgeries.

METHODS

Consecutive cardiac operations under cardiopulmonary bypass (200 adults, 144 men, 68 ± 11 years): 67 coronary artery bypass graft (CABG), 27 aortic valve surgery, 21 mitral valve surgery, 11 thoracic aorta surgery, and 74 combined surgery. Postoperative cTnI and CK-MB were measured on admission to the ICU and at fixed time until the fifth postoperative day.

RESULTS

Peak values of cTnI (median 5.8 ng/ml; interquartile range 3.6-11.9) and CK-MB (29.0 ng/ml; 15.6-60.4) were reached mainly within 18 h after the end of surgery (85% of cTnI and 95% of CK-MB highest determinations) without differences among groups. Cardiopulmonary bypass and cross-clamp time significantly correlated with markers' peak values. At multivariate analysis, mitral valve surgery showed greater cTnI, CK-MB, and their cumulative area under the curve than other isolated procedures. Thoracic aorta surgery showed lower cumulative area under the curve for both markers than CABG and combined surgery. Mitral valve surgery had significant later reduction of both markers in comparison with other procedures. No patient in mitral valve surgery group reached cTnI values in the normal laboratory range within 5 postoperative days.

CONCLUSION

Release pattern of cTnI and CK-MB after heart surgery depends on the type of procedure. Mitral valve surgery was characterized by highest and longest elevation of postoperative markers' concentration. Determinants of differences in myocardial injury biomarkers and their prognostic value after valve surgery should be accurately assessed.

Usefulness of colchicine to reduce perioperative myocardial damage in patients who underwent on-pump coronary artery bypass grafting

The objective of the present study was to test whether a perioperative course of colchicine, in patients who underwent standard coronary artery bypass grafting, would result in reduced postoperative increase of myocardial injury biomarker levels. Patients were prospectively randomized to colchicine or placebo starting 48 hours before scheduled coronary artery bypass grafting and for 8 days thereafter (0.5 mg twice daily). The primary outcome parameter was maximal high-sensitivity troponin T (hsTnT) concentration within 48 hours after surgery. Secondary outcome measures were maximal creatine kinase-myocardial brain fraction (CK-MB) levels and area under the curve (AUC) of hsTnT and CK-MB concentrations; 59 patients were included. Maximal hsTnT was 616 pg/ml (396 to 986) in the colchicine group versus 1,613 pg/ml (732 to 2,587) in controls (p = 0.002). Maximal CK-MB was 44.6 ng/ml (36.6 to 68.8) and 93.0 ng/ml (48.0 to 182.3), respectively (p = 0.002). The median AUC for hsTnT was 40,755 pg h/ml (20,868 to 79,176) in controls versus 20,363 pg h/ml (13,891 to 31,661) in the colchicine group (p = 0.002). AUCs for CK-MB were 2,552 ng h/ml (1,564 to 4,791) in controls and 1,586 ng h/ml (1,159 to 2,073) in the colchicine group (p = 0.003). The main complaints associated with colchicine were, as expected, gastrointestinal, with 5 patients (16.7%) in the colchicine group reporting diarrhea versus 1 control (3.4%) (p = 0.195). In conclusion, a short perioperative course of colchicine was effective in attenuating postoperative increases of hsTnT and CK-MB compared with placebo. This finding, which needs confirmation in a larger clinical trial powered to assess clinical endpoints, suggests a potential role for this agent in reducing cardiac surgery-related myocardial damage.

Consideration of a new definition of clinically relevant myocardial infarction after coronary revascularization: an expert consensus document from the Society for Cardiovascular Angiography and Interventions (SCAI)

Numerous definitions have been proposed for the diagnosis of myocardial infarction (MI) after coronary revascularization. The universal definition for MI designates post procedural biomarker thresholds for defining percutaneous coronary intervention (PCI)-related MI (type 4a) and coronary artery bypass grafting (CABG)-related MI (type 5), which are of uncertain prognostic importance. In addition, for both the MI types, cTn is recommended as the biomarker of choice, the prognostic significance of which is less well validated than CK-MB. Widespread adoption of a MI definition not clearly linked to subsequent adverse events such as mortality or heart failure may have serious consequences for the appropriate assessment of devices and therapies, may affect clinical care pathways, and may result in misinterpretation of physician competence. Rather than using an MI definition sensitive for small degrees of myonecrosis (the occurrence of which, based on contemporary large-scale studies, are unlikely to have important clinical consequences), it is instead recommended that a threshold level of biomarker elevation which has been strongly linked to subsequent adverse events in clinical studies be used to define a "clinically relevant MI." The present document introduces a new definition for "clinically relevant MI" after coronary revascularization (PCI or CABG), which is applicable for use in clinical trials, patient care, and quality outcomes assessment.

Myocardial damage following cardiac surgery: comparison between single-dose Celsior cardioplegic solution and cold blood multi-dose cardioplegia

Myocardial protection during cardiac surgery can be accomplished by different cardioplegic solutions. The aim of this study was to assess myocardial damage after heart valve surgery performed with myocardial protection of a single dose of Celsior cardioplegia or with repeated cold blood cardioplegia. After the stratification of 139 valvular patients by means of matching according to cross-clamp and cardiopulmonary bypass time, 32 patients were retained for comparison (16 patients received Celsior and 16 patients received cold blood cardioplegia). Creatine kinase-MB (CK-MB) and cardiac troponin I (cTnI) release were evaluated until six days after the operation. Pre-operative characteristics were similar in both groups. In the Celsior group, CK-MB and cTnI values were significantly higher from the first up to the sixth post-operative day. Peak cTnI values were 19.4 ± 13.4 and 9.7 ± 7 ng/mL (p=0.01) in the Celsior and the Cold Blood group, respectively. Peak CK-MB values were 79.6 ± 58.8 and 45.9 ± 20.6 U/L (p=0.07) in the Celsior and the Cold Blood group, respectively. Cold blood cardioplegia reduces perioperative myocardial damage compared to the Celsior solution in elective cardiac valve operations.

Prevalence and effect of myocardial injury after transcatheter aortic valve replacement

The incidence and prognostic implication of myocardial injury after transcatheter aortic valve replacement (TAVR) have not been consistently studied. We aimed to assess the incidence and extent of myocardial injury after TAVR performed using transfemoral and transapical approaches. The clinical data from patients with aortic stenosis who underwent TAVR were retrospectively analyzed. The myocardial necrosis markers cardiac troponin I and creatine kinase (CK)-MB were assessed during hospitalization. Of the 150 TAVR patients, 95% and 50% had an abnormally elevated cardiac troponin I and CK-MB level, respectively. The transapical patients had significantly greater elevations of both cardiac troponin I (13.8 ± 14.0 vs 2.5 ± 5.8 ng/ml, p <0.001) and CK-MB (28.4 ± 24.2 vs 7.4 ± 8.6 ng/ml, p ≤0.001). On receiver operating curve analysis, postprocedural CK-MB (twofold increase) had high predictive power for 30-day mortality (area under the curve 0.85, p <0.001). Patients with high CK-MB levels had greater rates of postprocedural kidney injury (22% vs 6%, p = 0.026), in-hospital (22% vs 0%, p <0.001), 30-day (27% vs 1.5%, p <0.001), and 1-year mortality (41% vs 18%, p = 0.01). Baseline renal failure and no β-blocker treatment on admission were independent predictors of an elevated postprocedural CK-MB level. In conclusion, a cardiac biomarker increase after TAVR was common and more frequent among transapical access patients. A twofold increase (>7 ng/ml) in CK-MB after transfemoral TAVR was a surrogate for poor long-term outcomes.

Cardioprotection during cardiac surgery

Coronary heart disease (CHD) is the leading cause of morbidity and mortality worldwide. For a large number of patients with CHD, coronary artery bypass graft (CABG) surgery remains the preferred strategy for coronary revascularization. Over the last 10 years, the number of high-risk patients undergoing CABG surgery has increased significantly, resulting in worse clinical outcomes in this patient group. This appears to be related to the ageing population, increased co-morbidities (such as diabetes, obesity, hypertension, stroke), concomitant valve disease, and advances in percutaneous coronary intervention which have resulted in patients with more complex coronary artery disease undergoing surgery. These high-risk patients are more susceptible to peri-operative myocardial injury and infarction (PMI), a major cause of which is acute global ischaemia/reperfusion injury arising from inadequate myocardial protection during CABG surgery. Therefore, novel therapeutic strategies are required to protect the heart in this high-risk patient group. In this article, we review the aetiology of PMI during CABG surgery, its diagnosis and clinical significance, and the endogenous and pharmacological therapeutic strategies available for preventing it. By improving cardioprotection during CABG surgery, we may be able to reduce PMI, preserve left ventricular systolic function, and reduce morbidity and mortality in these high-risk patients with CHD.

MASP-2 activation is involved in ischemia-related necrotic myocardial injury in humans

BACKGROUND/OBJECTIVES

Insufficient blood supply to the heart results in ischemic injury manifested clinically as myocardial infarction (MI). Following ischemia, inflammation is provoked and related to the clinical outcomes. A recent basic science study indicates that complement factor MASP-2 plays an important role in animal models of ischemia/reperfusion injury. We investigated the role of MASP-2 in human acute myocardial ischemia in two clinical settings: (1) Acute MI, and (2) Open heart surgery.

METHODS

A total of 187 human subjects were enrolled in this study, including 50 healthy individuals, 27 patients who were diagnosed of coronary artery disease (CAD) but without acute MI, 29 patients with acute MI referred for coronary angiography, and 81 cardiac surgery patients with surgically-induced global heart ischemia. Circulating MASP-2 levels were measured by ELISA.

RESULTS

MASP-2 levels in the peripheral circulation were significantly reduced in MI patients compared with those of healthy individuals or of CAD patients without acute MI. The hypothesis that MASP-2 was activated during acute myocardial ischemia was evaluated in cardiac patients undergoing surgically-induced global heart ischemia. MASP-2 was found to be significantly reduced in the coronary circulation of such patients, and the reduction of MASP-2 levels correlated independently with the increase of the myocardial necrosis marker, cardiac troponin I.

CONCLUSIONS

These results indicate an involvement of MASP-2 in ischemia-related necrotic myocardial injury in humans.

Early diagnosis of perioperative myocardial infarction after coronary bypass grafting: a study using biomarkers and cardiac magnetic resonance imaging

BACKGROUND

Myocardial injury related to coronary artery bypass grafting (CABG) is poorly characterized, and understanding the characteristic release of biomarkers associated with revascularization injury might provide novel therapeutic opportunities. This study characterized early changes in biomarkers after revascularization injury during on-pump CABG.

METHODS

This prospective study comprised 28 patients undergoing on-pump CABG and late gadolinium enhancement (LGE) cardiac magnetic resonance imaging (CMRI) who underwent measurements of cardiac troponin I (cTnI), creatine kinase-MB, and inflammatory markers (C-reactive protein, serum amyloid A, myeloperoxidase, interleukin 6, tumor necrosis factor-α, matrix metalloproteinase 9a, monocyte chemotactic protein-1, plasminogen activator inhibitor-1a) at baseline, at 1, 6, 12, and 24 hours, and at 1 week (inflammatory markers only) post-CABG. Biomarker results at 1 hour were studied for a relationship to new myocardial infarction as defined by CMRI-LGE, and the diagnostic utility of combining positive biomarkers was assessed.

RESULTS

All patients had an uneventful recovery, but 9 showed a new myocardial infarction demonstrated by new areas of hyperenhancement on CMR. Peak cTnI at 24 hours (ρ = 0.66, p < 0.001) and CK-MB (ρ = 0.66, p < 0.001) correlated with the amount of new LGE. At 1 hour, 3 biomarkers--cTnI, interleukin 6, and tumor necrosis factor-α--were significantly elevated in patients with vs those without new LGE. Receiver operating curve analysis showed cTnI was the most accurate at detecting new LGE at 1 hour: a cutoff of cTnI exceeding 5 μg/L at 1 hour had 67% sensitivity and 79% specificity for detecting new LGE.

CONCLUSIONS

Unexpected CABG-related myocardial injury occurs in a significant proportion of patients. A cTnI test at 1 hour after CABG could potentially differentiate patients with significant revascularization injury.

Cardioplegia and ventricular late potentials in cardiac surgical patients

BACKGROUND AND OBJECTIVE

Ventricular late potentials (LP) recording with signal-averaged electrocar- diogram allow identifying patients at risk of sudden death and ventricular tachycardia. Cardiac surgery with cardiopulmonary bypass (CPB) could predispose to the development of myocardial ischemia related to imperfect cardioplegia. To the best of our knowledge, no study investigated the protection of cardioplegia and CPB regarding the occurrence of LP in patients without previous myocardial infarction and undergoing cardiac surgery.

METHODS

In 61 elective patients scheduled for cardiac surgery involving CPB, signal-averaged electrocar- diogram was performed the day before and 24-48 h after the surgery. The electrodes were positioned according to Frank's orthogonal derivations. Twenty five patients were excluded because of poor quality signals, leaving 36 patients (age, 64 ± 14) available for the analyses. An abnormal signal-averaged electrocardiogram was considered when ≥2 of the recorded indexes were present. McNemar's tests were performed on the dichotomized values to investigate differences in pre-post scores.

RESULTS

The mean CPB duration was of 110 ± 57 min. Patients scheduled for cardiac surgery do not exhibited LP after CPB (no significant difference in pre-post CPB scores, P = NS). The probability of a patient with a negative score transitioning to a positive score was 0.23 (P = NS).

CONCLUSIONS

The present study in cardiac surgical patients suggests that cardioplegia associated to CPB has no significant impact on the occurrence of LP, irrespective of surgery performed.

Which troponometric best predicts midterm outcome after coronary artery bypass graft surgery?

BACKGROUND

Various troponin I measurements (troponometrics) have been used as surrogate markers of patient outcome after coronary artery bypass grafting (CABG). Our aim was to define the postoperative troponometric best able to predict in-hospital and late mortality.

METHODS

In 440 patients (seen from January 2000 to September 2004) undergoing isolated on-pump CABG with standardized anesthesia, perfusion, cardioplegia, and postoperative care, we followed all-cause mortality (census June 2009, 100% complete). Subjects underwent troponin I (cardiac troponin I [cTnI]) estimation at baseline and 6, 12, 24, 48, and 72 hours postoperatively, and individual time-point cTnI (T6, T12, T24, T48, T72), peak cTnI (Cmax), increase in cTnI between 6 and 12 hours (T↑6-12) and 6 and 24 hours (T↑6-24), cumulative area under the curve cTnI (CAUC24, CAUC48, and CAUC72), and cTnI≥13 ng·mL(-1) at any time point were each analyzed using univariate and multivariable Cox models to identify the probability of in-hospital and late death. Logistic EuroSCOREs and calculated creatinine clearance (CrCl) were also included. The Akaike information criterion (AIC) was used to determine goodness of fit.

RESULTS

There were 62 of 440 deaths after a median (interquartile range) follow-up period of 7.0 (5.7 to 8.1) years. Univariate Cox analysis demonstrated T12, T24, T48, T72, T↑6-12, T↑6-24, standardized CAUC24, CAUC48, and CAUC72 each to be predictors of midterm mortality. On Cox multivariable analysis in models incorporating both logistic EuroSCOREs and CrCl, both T72 (hazard ratio [HR], 95% confidence interval [CI], 1.10 [1.06 to 1.14]; p<0.001) and CAUC72 (1.45 [1.26 to 1.62], p<0.001) were identified as independent predictors of mortality. Of these, CAUC72 was superior based on the lowest AIC.

CONCLUSIONS

In myocardial protection studies, serial troponin I data should be collected until 72 hours postoperatively to calculate CAUC72, as this troponometric best predicts midterm mortality.

Biomonitors of cardiac injury and performance: B-type natriuretic peptide and troponin as monitors of hemodynamics and oxygen transport balance

Serum biomarkers, such as B-type natriuretic peptide and troponin, are frequently measured in the cardiac intensive care unit. A review of the evidence supporting monitoring of these biomarkers is presented.

DESIGN

A search of MEDLINE, PubMed, and the Cochrane Database was conducted to find literature regarding the use of B-type natriuretic peptide and troponin in the cardiac intensive care setting. Adult and pediatric data were considered.

RESULTS AND CONCLUSION

Both B-type natriuretic peptide and troponin have demonstrated utility in the intensive care setting but there is no conclusive evidence at this time that either biomarker can be used to guide inpatient management of children with cardiac disease. Although B-type natriuretic peptide and troponin concentrations can alert clinicians to myocardial stress, injury, or hemodynamic alterations, the levels can also be elevated in a variety of clinical scenarios, including sepsis. Observational studies have demonstrated that perioperative measurement of these biomarkers can predict postoperative mortality and complications.

RECOMMENDATION AND LEVEL OF EVIDENCE

(class IIb, level of evidence B): The use of B-type natriuretic peptide and/or troponin measurements in the evaluation of hemodynamics and postoperative outcome in pediatric cardiac patients may be beneficial.

Myocardial protection during aortic surgery: comparison between Bretschneider-HTK and cold blood cardioplegia

The ideal cardioplegic strategy in thoracic aorta operations requiring long cardiopulmonary bypass and cross-clamp time has not been established. Suboptimal myocardial protection may lead to myocardial damage and possible post-operative complications. We evaluate post-operative cardiac Troponin I (cTnI) release, low cardiac output syndrome (LCOS) and mortality, using a cold crystalloid single-dose intracellular or cold blood multidose cardioplegia in 112 elective or emergent thoracic aorta operation patients. Fifty-four patients (HTK group) received Custodiol® cardioplegic solution and 58 received cold blood cardioplegia (CB group). Cross-clamp time, cardiopulmonary bypass (CPB) time and cTnI peak release were similar in both groups. No differences were found for atrial and ventricular arrhythmias, inotropic support, LCOS and in-hospital mortality. Two-way ANOVA analysis revealed an interactive effect on cTnI peak (p=0.012) of cardioplegic solution type across the cross-clamp time quintile. In the fifth quintile, cross-clamp time patient (>160 min) cTnI peak value was higher in CB patients (p=0.044). HTK and CB cardioplegic solutions assure similar myocardial protection in patients undergoing thoracic aorta operations. In long cross-clamp times, the lower post-operative cTnI release detected using HTK may be indicative of a better myocardial protection in these extreme conditions.

Cardioprotective effects of electroacupuncture pretreatment on patients undergoing heart valve replacement surgery: a randomized controlled trial

BACKGROUND

Cardiac ischemia-reperfusion injury after cardiopulmonary bypass contributes to postoperative morbidity and mortality in patients with open-heart surgery. This randomized controlled trial was designed to address the protective effects of electroacupuncture (EA) pretreatment on myocardial injury in patients undergoing heart valve replacement surgery.

METHODS

Sixty patients with acquired heart valve disease were randomly allocated to the EA pretreatment group or the control group. Patients in the EA group received EA stimulus at bilateral Neiguan (PC 6), Lieque (LU 7), and Yunmen (LU 2) for 30 minutes each day for five consecutive days before surgery. Hemodynamic data, mechanical ventilation time, inotropic drug use in the intensive care unit, serum cardiac troponin I concentrations, morbidities, and mortalities were compared between the two groups. This trial is registered with ClinicalTrials.gov, number NCT00732459.

RESULTS

At 6 hours, 12 hours, and 24 hours after reperfusion, levels of serum cardiac troponin I were significantly decreased in the EA group (5.74 +/- 0.67, 6.22 +/- 0.66, and 5.21 +/- 0.58) compared with that in the control group (7.89 +/- 0.74, 8.34 +/- 1.08, and 7.57 +/- 0.89, p < 0.05). The EA pretreatment significantly reduced overall serum troponin I release at 6 hours, 12 hours, and 24 hours after aortic cross-clamp removal. Meanwhile, EA pretreatment also reduced the inotrope score at 12 hours, 24 hours, and 48 hours after the intensive care unit arrival and shortened intensive care unit stay time (p < 0.05).

CONCLUSIONS

The present study demonstrated that EA pretreatment may alleviate cardiac ischemia-reperfusion injury in adult patients undergoing heart valve replacements. This simple and convenient treatment has the potential to be used in the clinic for reducing myocardial injury in patients with heart valve replacement surgery.

Preoperative cardiac troponin I to assess midterm risks of coronary bypass grafting operations in patients with recent myocardial infarction

BACKGROUND

The optimal timing for coronary artery bypass grafting (CABG) in patients with recent acute myocardial infarction (AMI) is unclear. Cardiac troponin I (cTnI) is a widely accepted biomarker of myocardial damage. The objective of this study was to determine whether preoperative cTnI values could be used to determine risk stratification for CABG operations in patients with recent AMI.

METHODS

Evaluated were 184 patients who sustained an AMI within 21 days of undergoing nonurgent CABG operations. They were divided into two groups according to their preoperative cTnI values: 117 patients with cTnI of 0.15 ng/mL or less and 67 with cTnI exceeding 0.15 ng/mL. Associations between study variables and events were assessed with logistic regression modelling. Time from AMI to operation was evaluated to define preoperative cTnI variation.

RESULTS

Values of cTnI tended to decrease when the interval between AMI and the operation increased. Preoperative cTnI values were significantly associated with a higher incidence of major postoperative complications (low cardiac output syndrome, intraaortic balloon pump necessity, mechanical ventilation >72 hours, acute renal failure, in-hospital mortality). Perioperative myocardial damage was more pronounced in patients with cTnI exceeding 0.15 ng/mL. Multivariate analyses revealed cTnI exceeding 0.15 ng/mL was an independent predictor for 6-month mortality (odds ratio, 3.7; p = 0.043).

CONCLUSIONS

Preoperative cTnI exceeding 0.15 ng/mL in patients with recent AMI undergoing CABG is associated with higher postoperative myocardial damage and is a strong determinant of postoperative morbidity and mortality within the 6-month period.

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.

Troponin is superior to electrocardiogram and creatinine kinase MB for predicting clinically significant myocardial injury after coronary artery bypass grafting

AIMS

Cardiac biomarkers are routinely elevated after uncomplicated cardiac surgery to levels considered diagnostic of myocardial infarction in ambulatory populations. We investigated the diagnostic power of electrocardiogram (ECG) and cardiac biomarker criteria to predict clinically relevant myocardial injury using benchmarks of mortality and increased hospital length of stay (HLOS) in patients undergoing coronary artery bypass graft (CABG) surgery.

METHODS AND RESULTS

Perioperative ECGs, creatinine kinase MB fraction, and cardiac troponin I (cTnI) were assessed in 545 primary CABG patients. None of the ECG criteria for myocardial injury predicted mortality or HLOS. However, post-operative day (POD) 1 cTnI levels independently predicted 5-year mortality (hazard ratio = 1.42; 95% CI 1.14-1.76 for each 10 microg/L increase; P = 0.009), while adjusting for baseline demographic characteristics and perioperative risk factors. Moreover, cTnI was the only biomarker that significantly improved the prediction of 5-year mortality estimated by the logistic Euroscore (P = 0.02). Furthermore, the predictive value of cTnI for 5-year mortality was replicated in a separately collected cohort of 1031 CABG patients using cardiac troponin T.

CONCLUSION

Electrocardiogram diagnosis of post-operative myocardial injury after CABG does not independently predict an increased risk of 5-year mortality or HLOS. Conversely, cTnI is independently associated with an increased risk of mortality and prolonged HLOS.

Release of cardiac biochemical and inflammatory markers in patients on cardiopulmonary bypass undergoing coronary artery bypass grafting

BACKGROUND

Determination of cardiac markers can assess cardiac injury induced by cardiopulmonary bypass (CPB) during coronary artery bypass grafting (CABG). However, the markers and their release pattern are not well defined. This study was aimed at assessing the release and timing of cardiac biochemical and inflammatory markers in patients undergoing elective CABG with CPB.

METHODS

Forty patients undergoing elective CABG were included in this study. Blood samples were collected for biochemical measurements at the following time points: immediately prior to the induction of anesthesia, one, six, 12, and 24 hours after initiation of CPB.

RESULTS

Increased release of cardiac troponin I was observed one hour after initiation of CPB (p < 0.05) and reached the maximum at 12 hours after CPB (p < 0.01). Serum CK-MB enzyme activity and CK-MB mass both were highly elevated starting at one hour after initiation of CPB, peaked at six hours, and remained elevated until 24 hours after CPB. Both lactate and lactate dehydrogenase were highly elevated six hours after CPB and peaked at 12 hours after CPB (p < 0.01). Serum levels of interleukin-6 and tumor necrosis factor-alpha increased significantly one hour after initiation of CPB and peaked at six hours (p < 0.01), while serum high sensitivity C-reactive protein levels started to elevate 12 hours after CPB (p < 0.01).

CONCLUSION

Monitoring of these markers could help to determine implementation of protective interventions during CABG with CPB to prevent myocardial deterioration and to predict the risk and prognosis.

Troponin after cardiac surgery: a predictor or a phenomenon?

BACKGROUND

Increased cardiac troponin is observed after virtually every cardiac operation, indicating perioperative myocardial injury. The clinical significance of this elevation is controversial. This study aimed to correlate postoperative troponin levels with major adverse cardiac events (MACE).

METHODS

The study included 1918 consecutive patients undergoing adult cardiac operations, including 1515 isolated coronary procedures, 229 valvular operations, and 174 combined coronary/valve procedures. Peak troponin T (normal value < 0.1 microg/L) was measured at less than 24 hours postoperatively. Excluded were 506 patients with a recent myocardial infarction (< 30-days of operation). The primary outcome was a composite of death, electrocardiogram-defined infarction, and low output syndrome (MACE).

RESULTS

Mortality rates were 1.4%, 6.1%, and 7% in the coronary bypass, valve, and combined groups, respectively (p < 0.001). The rates of MACE were 17%, 35%, and 44% (p < 0.0001), and mean troponin T levels were 0.9 +/- 1.5, 1.2 +/- 2.9, and 1.3 +/- 1.2 microg/L (p < 0.001), in the coronary bypass, valve, and combined groups, respectively. All patients were divided into quintiles based on their peak postoperative troponin level (Q1, 0.0 to 0.39; Q2, 0.4 to 0.59; Q3, 0.6 to 0.79; Q4, 0.8 to 1.29; and Q5, > 1.3 microg/L). Adverse outcomes were similar and stable in the lower quintiles. A stepwise increase in adverse outcomes was observed in the higher quintiles. Receiver operating characteristic curve analysis revealed a troponin cutoff of 0.8 microg/L was the most discriminatory for MACE (area under the curve, 0.7). Multivariable analyses showed a troponin value of more than 0.8 microg/L was independently associated with MACE.

CONCLUSIONS

Moderate elevations in troponin are common after cardiac operations; troponin is a well-described predictor of outcomes. Troponin levels exceeding 0.8 microg/L are associated with increased MACE in patients without a history of preoperative myocardial infarction within 30 days of operation.

Elective cardiac surgery using Celsior or St. Thomas No. 2 solution: a prospective, single-center, randomized pilot study

OBJECTIVE

Celsior is a crystalloid solution specifically designed for solid-organ transplantation. Due to its advanced combination of solutes, we wanted to evaluate its safety, efficacy, and possible benefits when used as blood cardioplegia in elective cardiac surgery in a single-center, randomized, controlled clinical trial, comparing its performance with a well-established cardioplegic solution.

METHODS

Patients programmed for aortic valve replacement were randomized to receive either St. Thomas No. 2 or Celsior as blood cardioplegia with the same administration protocol. Intraoperative and postoperative variables concerning myocardial protection were registered and compared.

RESULTS

A total of 60 patients were enrolled and randomized (Celsior, 30; St. Thomas, 30). There were no significant differences in baseline and preoperative variables. Volume of cardioplegic solution, number of administrations needed and the amount of potassium added were similar in both groups. Patients in the Celsior group showed a higher incidence of spontaneous sinus rhythm after myocardial ischemia (77% vs 40%, p=0.004) and fewer patients required defibrillation (17% vs 43%, p=0.024) for ventricular reperfusion arrhythmias. Postoperatively, there were no significant differences in troponin I release, inotropic and vasopressor drug support, ICU stay, and postoperative evolution. There were no deaths in the study.

CONCLUSIONS

Celsior solution used as blood cardioplegia is effective and seems to be safe in elective aortic valve replacement when compared in this pilot study with a standard cardioplegic solution used worldwide. Fast return to sinus rhythm and lower incidence of reperfusion arrhythmias in the Celsior group may reflect a better myocardial protection during cardioplegic arrest. More investigation is needed to elucidate its performance in elective surgery.

Myocardial injury after off-pump coronary artery bypass grafting operation

OBJECTIVE

Perioperative myocardial ischemia is less pronounced in off-pump coronary artery bypass (OPCAB) compared to on-pump coronary artery bypass; however, the threshold over which the postoperative release of cardiac troponin I (cTnI) release and creatine kinase-MB (CK-MB) after OPCAB should be considered clinically relevant is unknown. The study was designated to evaluate if perioperative myocardial damage, measured by means of postoperative release of cTnI and CK-MB, has an influence on short- and mid-term outcome after OPCAB operations.

METHODS

Two hundred and sixty-one unselected patients undergoing OPCAB had cTnI and CK-MB measured preoperatively and nine times postoperatively. Postoperative peak values were evaluated and the 80th percentiles were used to segregate the population into two groups for each marker. The following cut-offs were used: 7.1 ng/dl for cTnI peak and 36.3 ng/dl for CK-MB peak.

RESULTS

Patients with cTnI>7.1 ng/ml (n=51) and CK-MB>36.3 ng/ml (n=48) had a longer mechanical ventilation and ICU length of stay. Nevertheless, hospital mortality did not differ between groups. Survival after 3 years was 92.8+/-2.3% and 81.8+/-6.2 for patients with postoperative cTnI peak<or=7.1 ng/ml and >7.1 ng/ml, respectively (p=0.003). It was 93+/-2.2% and 80+/-6.8% for patients with CK-MB<or=36.3 ng/ml and >36.3 ng/ml, respectively (p=0.005). Adjusted hazard ratios for mid-term mortality were HR 2.7 (CI 1-7.6), p=0.05 for cTnI>7.1 ng/dl and HR 3.1 (CI 1-9.1), p=0.04 for CK-MB>36.3 ng/ml.

CONCLUSION

Perioperative myocardial damage should not be considered an innocuous event following OPCAB operations since the survival rate over 3 years is significantly worse in patients with the highest postoperative peak release of cTnI and CK-MB.

Glucose-insulin-potassium and tri-iodothyronine individually improve hemodynamic performance and are associated with reduced troponin I release after on-pump coronary artery bypass grafting

BACKGROUND

Both glucose-insulin-potassium (GIK) and tri-iodothyronine (T3) may improve cardiovascular performance after coronary artery surgery (CABG) but their effects have not been directly compared and the effects of combined treatment are unknown.

METHODS AND RESULTS

In 2 consecutive randomized double-blind placebo-controlled trials, in patients undergoing first time isolated on-pump CABG between January 2000 and September 2004, 440 patients were recruited and randomized to either placebo (5% dextrose) (n=160), GIK (40% dextrose, K+ 100 mmol.L(-1), insulin 70 u.L(-1)) (0.75 mL.kg(-1) h(-1)) (n=157), T3 (0.8 microg.kg(-1) followed by 0.113 microg.kg(-1) h(-1)) (n=63) or GIK+T3 (n=60). GIK/placebo therapy was administered from start of operation until 6 hours after removal of aortic cross-clamp (AXC) and T3/placebo was administered for a 6-hour period from removal of AXC. Serial hemodynamic measurements were taken up to 12 hours after removal of AXC and troponin I (cTnI) levels were assayed to 72 hours. Cardiac index (CI) was significantly increased in both the GIK and GIK/T3 group in the first 6 hours compared with placebo (P<0.001 for both) and T3 therapy (P=0.009 and 0.029, respectively). T3 therapy increased CI versus placebo between 6 and 12 hours after AXC removal (P=0.01) but combination therapy did not. Release of cTnI was lower in all treatment groups at 6 and 12 hours after removal of AXC.

CONCLUSIONS

Treatment with GIK, T3, and GIK/T3 improves hemodynamic performance and results in reduced cTnI release in patients undergoing on-pump CABG surgery. Combination therapy does not provide added hemodynamic effect.