Cardiac troponin T for prediction of short- and long-term morbidity and mortality after elective open heart surgery

Postoperative Troponin Levels in Children Undergoing Open Heart Surgery With and Without Coronary Intervention

We aimed to characterize the ranges, temporal trends, influencing factors, and prognostic significance of postoperative troponin levels after congenital heart surgery. This single-center retrospective study included patients from 2006 to 2021 who had ≥ 1 postoperative troponin-T measurement collected within 96 h of congenital heart surgery (CHS). Patients were grouped as Anomalous Aortic Origin of the Coronary Artery-"AAOCA repair," or congenital heart surgery with "Other Coronary Interventions" other than AAOCA repair, or "No Coronary Intervention." In each group, information on concomitant surgery requiring one or more of the following-atriotomy, ventriculotomy, right ventricular muscle bundle resection, and/or septal myectomy-was collected. Clinical correlates of troponin values were analyzed in three postoperative windows: < 8, 8-24, and 24-48 h. The highest median [range] troponin levels (ng/mL) for the samples were 0.34 [0.06, 1.32] at < 8 h for "AAOCA repair," 1.35 [0.14, 12.0] at < 8 h for those undergoing CHS with "Other Coronary Interventions," and 0.87 [0.06, 25.1] at 8-24 h for those undergoing CHS with "No Coronary Interventions." Atriotomy was associated with higher median troponin levels in the AAOCA group at < 8 h (0.40 [0.31, 0.77] vs. 0.29 [0.17, 0.54], P = 0.043) and in the Other Coronary Intervention group at 8-24 h (1.67 [1.04, 2.63] vs. 0.40 [0.19, 1.32], P = 0.002). Patients experiencing major postoperative complications (vs. those who did not) had higher troponin levels in the AAOCA group as early as 8-24 h (0.36 [0.24, 0.57] vs. 0.21 [0.14, 0.33], P = 0.03). Similar findings were noted in the Coronary Intervention (2.20 [1.34, 3.90] vs. 1.11 [0.51, 2.90], P = 0.028) and No Coronary Intervention (2.2 [1.49, 15.1] vs. 0.74 [0.40, 2.34], P = 0.027) groups but earlier at < 8 h. In the AAOCA group, 2/18 (11%) troponin outliers experienced cardiac arrest in comparison to 0/80 (0%) non-outliers (P = 0.032). In the Other Coronary Intervention group, troponin outliers had longer median times to ICU discharge (10 vs. 4 days) and hospital discharge (21 vs. 10 days) (both P < 0.001). Postoperative troponin levels depend on a multitude of factors and may have prognostic value in patients undergoing congenital heart surgery with coronary interventions.

Risk factors for postoperative myocardial injury-related cardiogenic shock in patients undergoing cardiac surgery

BACKGROUND

Myocardial injury-related cardiogenic shock (MICS) is significantly associated with poor outcomes in patients after cardiac surgery. Herein, we aimed to investigate the risk factor for postoperative MICS.

METHODS

We performed a case-control study on 792 patients undergoing cardiac surgery from 2016 to 2019, including 172 patients with postoperative MICS and 620 age- and sex-matched controls. MICS was defined as composite criteria: a cardiac index of < 2.2 L/m²/min, arterial lactate levels of > 5 mmol/L at the end of the surgery, a vasoactive-inotropic score of > 40 at the end of the surgery, and a cardiac troponin T (cTnT) level of > 0.8 µg/L on postoperative day 1 (POD1) with an increase of > 10% on POD 2.

RESULTS

A total of 4671 patients who underwent cardiac surgery in our hospital between 2016 and 2019 were included; of these, 172 (3.68%) had MICS and the remaining 4499 did not. For investigating the risk factors, we selected 620 age- and sex-matched controls. In the univariate analysis, MICS was significantly associated with death (P < 0.05), extracorporeal membrane oxygenation (P < 0.05), continuous renal replacement therapy (P < 0.01), and ventricular arrhythmias (P < 0.05). Multivariable logistic regression analysis revealed that diabetes mellitus (OR:8.11, 95% CI: 3.52-18.66, P < 0.05) and a cardiopulmonary bypass (CPB) time of > 2 h (OR: 3.16, 95% CI: 1.94-5.15, P < 0.05) were associated with postoperative MICS. Moreover, long-time administration of preoperative calcium channel blocker (CCB) was associated with a less incidence of MICS (OR: 0.11, 95% CI: 0.05-0.27, P < 0.05).

CONCLUSIONS

Postoperative MICS is significantly associated with poor outcomes. Diabetes mellitus and long CPB time are associated with MICS. Preoperative CCB administration is associated with less incidence of MICS.

The low-dose colchicine in patients after non-CABG cardiac surgery: a randomized controlled trial

BACKGROUND

Recent high-quality trials have shown that the anti-inflammatory effects of colchicine reduce the risk of cardiovascular events in patients suffering post-myocardial infarction and chronic coronary disease. The effect of colchicine in patients undergoing non-coronary artery bypass grafting (non-CABG) with cardiopulmonary bypass remains unclear. We aim to evaluate the effect of colchicine on myocardial protection in patients who underwent non-CABG cardiac surgery.

METHOD

Patients were randomly assigned to colchicine or placebo groups starting 72 h before scheduled cardiac surgery and for 5 days thereafter (0.5 mg daily).The primary outcome was the level of cardiac troponin T (cTnT) at postoperative 48 h. The secondary outcomes included troponin I (cTnI) and creatine kinase-MB (CK-MB), inflammatory biomarkers (procalcitonin and interleukin-6, etc.), and adverse events (30-day mortality, stroke, ECMO and IABP use, etc.).

RESULTS

A total of 132 patients underwent non-CAGB cardiac surgery, 11were excluded because of diarrhea (n = 6) and long aortic cross-clamp time > 2 h (n = 5), 59 were assigned to the colchicine group and 62 to the placebo group. Compared with the placebo group, cTnT (median: 0.3 μg/L, IQR 0.2-0.4 μg/L vs. median: 0.4 μg/L, IQR 0.3-0.6 μg/L, P < 0.01), cardiac troponin I (median: 0.9 ng/ml, IQR 0.4-1.7 ng/ml vs. median: 1.3 ng/ml, IQR 0.6-2.3 ng/ml, P = 0.02), CK-MB (median: 1.9 ng/ml, IQR 0.7-3.2 ng/ml vs. median: 4.4 ng/ml, IQR 1.5-8.2 ng/ml, P < 0.01), and interleukin-6 (median: 73.5 pg/ml, IQR 49.6-125.8 pg/ml vs. median: 101 pg/ml, IQR 57.5-164.7 pg/ml, P = 0.048) were significantly reduced in colchicine group at postoperative 48 h. For safety evaluation, the colchicine (n = 65) significantly decreased post-pericardiotomy syndrome (3.08% vs. 17.7%, P < 0.01) and increased the rate of diarrhea (9.23% vs. 0, P = 0.01) compared with the placebo group (n = 62). No significant difference was observed in other adverse events between the two groups.

CONCLUSION

A short perioperative course of low-dose colchicine was effective to attenuate the postoperative biomarkers of myocardial injury and inflammation, and to decrease the postoperative syndrome compared with the placebo. Trial registration ChiCTR2000040129. Registered 22nd Nov. 2020. This trial was registered before the first participant was enrolled. http://www.chictr.org.cn/showproj.aspx?proj=64370 .

Effect of aortic cross-clamp time on late survival after isolated aortic valve replacement

OBJECTIVES

Longer aortic cross-clamp (ACC) time is associated with decreased early survival after cardiac surgery. Because maximum follow-up in previous studies on this subject is confined to 28 months, it is unknown whether this adverse effect is sustained far beyond this term. We aimed to determine whether longer ACC time was independently associated with decreased late survival after isolated aortic valve replacement in patients with severe aortic stenosis during 25 years of follow-up.

METHODS

In this retrospective cohort study, multivariable analysis was performed to identify possible independent predictors of decreased late survival, including ACC and cardiopulmonary bypass (CPB) time, in a cohort of 456 consecutive patients with severe aortic stenosis, who had undergone isolated aortic valve replacement between 1990 and 1993.

RESULTS

Mean follow-up was 25.3 ± 2.7 years. Median (interquartile range) and mean ACC times were normal: 63.0 (20.0) and 64.2 ± 16.1 min, respectively. Age, operative risk scores and New York Heart Association class were similar in patients with ACC time above, versus those with ACC time below the median. Longer ACC time was independently associated with decreased late survival: hazards ratio (HR) 1.01 per minute increase of ACC time (95% confidence interval [CI] 1.00-1.02; P = 0.012). Longer CPB time was not associated with decreased late survival (HR 1.00 per minute increase of CPB time [95% CI 1.00-1.00; P = 0.30]).

CONCLUSIONS

Longer ACC time, although still within normal limits, was independently associated with decreased late survival after isolated aortic valve replacement in patients with severe aortic stenosis.

Prognostic Value of High-Sensitivity Troponin T After On-Pump Coronary Artery Bypass Graft Surgery

INTRODUCTION

High-sensitivity troponin T (hs-TnT), as a single or serial measurement to predict postoperative mortality and morbidity, appears to be attractive due to its direct relationship in assessing myocardial damage and the widespread availability of hs-TnT testing. Therefore, this study aimed to identify any prognostic value of hs-TnT in predicting in-hospital outcomes after coronary artery bypass graft (CABG) surgery.

METHOD

We identified all consecutive patients who underwent on-pump CABG between July 2011 and December 2018. To evaluate the prognostic value of hs-TnT after CABG, we assessed the probability and odds ratio (OR) of adverse events concerning the maximum value of postoperative hs-TnT (measured within 24 hrs). TnT was routinely collected at 0, 6, 12 and 72 hours postoperatively. Values were categorised into intervals of 200 for analysis. A fully Bayesian logistic regression of the adverse event with the troponin T interval (0-200) as the reference level was used. A subgroup analysis was performed in patients with normal and elevated preoperative hs-TnT (< or ≥30 ng/L). The pre-specified primary outcome was a major adverse cardiac or cerebrovascular event (MACCE), defined as a composite of death within 30 days of operation for any cause, myocardial infection (MI), or stroke.

RESULTS

1,318 people underwent on-pump CABG during this period. One hundred and twenty-three (123) (9.3%) experienced MACCE, 14 (1.1%) experienced death within 30 days, 105 (8.0%) experienced MI and 14 (1.1%) experienced stroke. Compared to the reference category (hs-TnT ≤200 ng/L) we found there was an increase in OR with increasing level of hs-TnT for MACCE (p<0.001), 30-day mortality (p=0.003), MI (p<0.001) and ICU stay >48 hours (p<0.001). However, there was no statistically significant association present between hs-TnT and stroke, readmission to the intensive care unit (ICU), return to theatre for bleeding, or new-onset renal dysfunction.

CONCLUSION

Peak hs-TnT level, greater than 400 ng/L, measured within 24 hours after CABG surgery is associated with MACCE, 30-day mortality, MI and ICU stay >48 hours. Prospectively designed trials, with clear prognostic and outcome variables, may provide further insight into the prognostic value of hs-TnT post-CABG.

Effects of peak time of myocardial injury biomarkers on mid-term outcomes of patients undergoing OPCABG

BACKGROUND

With the development of cardiac surgery techniques, myocardial injury is gradually reduced, but cannot be completely avoided. Myocardial injury biomarkers (MIBs) can quickly and specifically reflect the degree of myocardial injury. Due to various reasons, there is no consensus on the specific values of MIBs in evaluating postoperative prognosis. This retrospective study was aimed to investigate the impact of MIBs on the mid-term prognosis of patients undergoing off-pump coronary artery bypass grafting (OPCABG).

METHODS

Totally 564 patients undergoing OPCABG with normal courses were included. Cardiac troponin T (cTnT) and creatine kinase myocardial band (CK-MB) were assessed within 48 h before operation and at 6, 12, 24, 48, 72, 96 and 120 h after operation. Patients were grouped by peak values and peak time courses of MIBs. The profile of MIBs and clinical variables as well as their correlations with mid-term prognosis were analyzed by univariable and multivariable Cox regression models.

RESULT

Continuous assessment showed that MIBs increased first (12 h after surgery) and then decreased. The peak cTnT and peak CK-MB occurred within 24 h after operation in 76.8% and 67.7% of the patients respectively. No significant correlation was found between CK-MB and mid-term mortality. Delayed cTnT peak (peak cTnT elevated after 24 h after operation) was correlated with lower creatinine clearance rate (69.36 ± 21.67 vs. 82.18 ± 25.17 ml/min/1.73 m²), body mass index (24.35 ± 2.58 vs. 25.27 ± 3.26 kg/m²), less arterial grafts (1.24 ± 0.77 vs. 1.45 ± 0.86), higher EuroSCORE II (2.22 ± 1.12 vs.1.72 ± 0.91) and mid-term mortality (26.5 vs.7.9%). Age (HR: 1.067, CI: 1.006-1.133), left ventricular ejection fraction (HR: 0.950, CI: 0.910-0.993), New York Heart Association score (HR: 1.839, CI: 1.159-2.917), total venous grafting (HR: 2.833, CI: 1.054-7.614) and cTnT peak occurrence within 24 h (HR: 0.362, CI: 0.196-0.668) were independent predictors of mid-term mortality.

CONCLUSION

cTnT is a better indicator than CK-MB. The peak value and peak occurrence of cTnT are related to mid-term mortality in patients undergoing OPCABG, and the peak phases have stronger predictive ability.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR2000033850. Registered 14 June 2020, http://www.chictr.org.cn/edit.aspx?pid=55162&htm=4 .

Association of early elevated cardiac troponin I concentration and longitudinal change after off-pump coronary artery bypass grafting and adverse events: a prospective cohort study

Background

The elevation of troponin after coronary artery bypass grafting (CABG) is common This study aimed to investigate the association between very early cardiac troponin I (cTnI) concentration and its longitudinal change within 24 hours after CABG and 30-day adverse events.

Methods

This study prospectively enrolled 633 patients who underwent isolated off-pump CABG from January 2019 to May 2019. Serum cTnI levels were measured in all patients at two examinations within 24 hours postoperatively (1 hour and 12–18 hours), and a proportional hazards model was used to determine the association between cTnI levels and their change with adverse events, which were defined as a composite of 30-day mortality, stroke, heart failure, myocardial infarction (MI), and ventricular fibrillation.

Results

cTnI levels of the two examinations and absolute change of cTnI levels were significantly higher in the event group than in the non-event group (P<0.01, both). Earlier and later cTnI concentrations were associated with 30-day complications [adjusted hazard ration (HR) 1.598, 95% confidence interval (CI), 1.158–2.204 and HR 1.499, 95% CI, 1.228–1.831, respectively]. With regard to longitudinal change in cTnI levels, participants with persistently high levels of cTnI and those with progression from a low level to high level concentration experienced a significantly increased risk of adverse events than did participants who had a trend of persistently low cTnI levels (HR 3.105, 95% CI, 1.748–5.517 versus HR 2.944, 95% CI, 1.488–5.824).

Conclusions

Longitudinal change in cTnI levels within 24 hours and early cTnI concentrations, even less than 1 hour after CABG, are associated with adverse events. These data will be useful in identifying patients at an increased risk of complications.

Markers of Poor Prognosis in Patients Requiring Continuous Renal Replacement Therapy After Cardiac Surgery

OBJECTIVE

Acute kidney injury requiring renal replacement therapy after cardiac surgery has an incidence of 2% to 15%, and mortality in affected patients approximates 50%. The authors aimed to study the determinants of poor prognosis in patients receiving continuous renal replacement therapy (CRRT) after cardiac surgery.

DESIGN

Retrospective, observational single-center study.

SETTING

Tertiary care, university hospital.

PARTICIPANTS

Cardiac surgery patients admitted to the intensive care unit (ICU) needing postoperative CRRT between January 1, 2010, and September 31, 2019.

INTERVENTIONS

Predictors of mortality were examined using groupwide comparisons between ICU survivors versus nonsurvivors and univariate and multivariate Cox proportional hazards models.

RESULTS

During the study period, 67 cardiac surgery patients without prior maintenance dialysis required CRRT postoperatively. ICU mortality was 47.7% and 90-day mortality was 58.2%. Only 37.3% of patients were alive at 1 year after surgery. Blood lactate at the start of dialysis was the most significant predictor of ICU and overall mortality. Eighty-seven percent of patients with lactate >3 mmol/L died in the ICU compared with 27.3% of patients with lactate ≤3 mmol/L (p < 0.0001). In patients with lactate exceeding 5.3 mmol/L, ICU mortality was 100%. In a stepwise multivariate Cox proportional hazards model, the association with mortality remained significant for lactate at the start of CRRT (per 1 mmol/L, hazard ratio [HR] 1.19 [95% confidence interval {CI} 1.11-1.28], p < 0.0001), troponin T on the first postoperative morning (per 0.1 µg/L, HR 1.004 [95% CI 1.001-1.008], p = 0.01), and 72-hour fluid balance (per 1000 mL, HR 1.12 [95% CI 1.04-1.21], p = 0.005).

CONCLUSION

Blood lactate at the start of dialysis was the most significant predictor of ICU and overall mortality in patients with CRRT after cardiac surgery.

Heparin-binding protein measurement improves the prediction of myocardial injury-related cardiogenic shock

Background

Heparin-binding protein (HBP), a potent inducer of increased vascular permeability, is a potentially useful biomarker for predicting outcomes in patients with postoperative myocardial injury-related cardiogenic shock (MIRCS). We aimed to evaluate and validate HBP as a prognostic biomarker for postoperative MIRCS.

Methods

We performed a case-control study in 792 patients undergoing cardiac surgery from January 1, 2016, to August 1, 2019, including 172 patients with postoperative MIRCS and 620 age- and sex-matched controls. The association between HBP and MIRCS was determined by multivariate logistic regression analysis. Receiver operating characteristic curves (ROCs) with area under the curve (AUC) were performed to calculate the cut-off value, sensitivity and specificity. The association between HBP and cardiac troponin T (cTnT) was determined by multivariable linear regression analysis. Blood samples were drawn from the coronary sinus and arterial line of the cardiopulmonary bypass (CPB) before aortic cross-clamping (time point 1) and 5 min after aortic declamping (time point 2).

Results

Before aortic cross-clamping, coronary sinus HBP (HBP_CS1) showed no differences between the two groups. However, after declamping, the MIRCS group had a significantly higher sinus HBP level (HBP_CS2) than did the control group. HBP_CS2 predicted MIRCS with an AUC of 0.85 (95% CI: 0.81–0.89, cut-off: 220 ng/ml, sensitivity: 92% and specificity: 70%). After adjusting for confounding factors, we found that HBP was an independent risk factor for MIRCS (OR: 7.65, 95% CI: 4.86–12.06, P < 0.01) and was positively associated with cTnT (β > 0, P < 0.01).

Conclusions

Elevated levels of coronary sinus HBP were useful biomarkers for predicting MIRCS after cardiac surgery.

Troponin elevation in the setting of exercise-induced rhabdomyolysis in an athletic teenager

Troponin levels are often obtained when chest pain is evaluated in the paediatric emergency department. Elevations in troponin levels can be due to different causes, and it is important to fully understand all of these possible causes to help streamline further evaluation and therapy. We present the case of a teenager who had two episodes of troponin elevation in the setting of rhabdomyolysis.

Single-center experience with the combination of Cardioplexol™ cardioplegia and MiECC for isolated coronary artery bypass graft procedures

Background

Cardioplexol™ with its low volume (100 mL) was originally conceived as cardioplegic solution for MiECC procedures. Introduced in its current form in 2008 in our clinic, it has immediately demonstrated attractive advantages including the easy and rapid administration by the surgeon him/herself, the almost immediate cardiac arrest and a prolonged delay before a second dose is necessary. We report here the results of our initial experience with this simple solution.

Methods

Single centre, retrospective observational analysis of prospectively collected data of isolated coronary artery bypass graft (CABG) procedures performed with a MiECC.

Results

Of 7,447 adult cardiac surgical operations performed during a 76 months period, 2,416 were isolated CABG-MiECC procedures. Patients were 81.3% males, 66.2±9.7 years old and had a median logistic EuroSCORE of 3.2. In average 3.2±0.8 vessels were bypassed. Median cross-clamp time was 45 minutes and more than 75% of the patients received only one 100 mL dose of Cardioplexol™. At reperfusion more than 90% of the hearts spontaneously recovered a rhythmic activity. Maximal value of troponin T during the first hours following myocardial reperfusion was 0.9±4.5 ng/mL (median =0.4 ng/mL). Mortality at 30 days was 0.9%.

Conclusions

Cardioplexol™ seems very promising. It appears especially efficient and safe when used for CABG procedures performed with a MiECC.

Clinical Relevance of Troponin T Profile Following Cardiac Surgery

Background: Peak post-operative cardiac troponin T (cTnT) independently predicts mid- and long-term outcome of cardiac surgery patients. A few studies however have reported two peaks of cTnT over the first 48–72 h following myocardial reperfusion. The aim of the current study was to better understand underlying reasons of these different cTnT profiles and their possible relevance in terms of clinical outcome.

Methods: All consecutive adult cardiac surgical procedures performed with an extra-corporeal circulation during a >6 years period were retrospectively evaluated. Patients with a myocardial infarction (MI) < 8 days were excluded. cTnT profile of patients with at least one value ≥1 ng/mL value were categorized according to the time occurrence of the peak value. Univariable and multivariable analysis were performed to identify factors influencing early vs. late increase of cTnT values, and to verify the correlation of early vs. late increase with clinical outcome.

Results: Data of 5,146 patients were retrieved from our prospectively managed registry. From 953 with at least one cTnT value ≥1 ng/mL, peak occurred ≤ 6 h (n = 22), >6 to ≤ 12 h (n = 366), >12 to ≤ 18 h (n = 176), >18 to ≤ 24 h (171), >24 h (218). Age (OR: 1.023; CI: 1.016–1.030) and isolated CABG (OR: 1.779; CI: 1.114–2.839) were independent predictors of a late increase of cTnT over a limit of 1 ng/ml (p < 0.05), whereas isolated valve procedures (OR: 0.685; CI: 0.471–0.998) and cross-clamp duration (OR: 0.993; CI: 0.990–0.997) independently predicted an early elevation (p < 0.05). Delayed elevation as opposed to early elevation correlated with a higher rate of post-operative complications including MI (19.8 vs. 7.2%), new renal insufficiency (16.3 vs. 6.7%), MACCE (32.0 vs. 15.5%), or death (7.4 vs. 4.4%).

Conclusion: Profile of cTnT elevation following cardiac surgery depends on patients' intrinsic factors, type of surgery and duration of cross-clamp time. Delayed increase is of higher clinically relevance than prompt post-operative elevation.

High-sensitivity troponin T release profile in off-pump coronary artery bypass grafting patients with normal postoperative course

BACKGROUND

The aim of the study was to investigate the high-sensitivity troponin T (hs-TnT) release profile in off-pump coronary artery bypass grafting (OPCABG) patients with normal postoperative course.

METHODS

From January 2015 to October 2016, 398 consecutive OPCABG patients who had normal postoperative courses were enrolled. Blood samples for hs-TnT were collected at several time points and the comparisons among different time points grouped by various factors were further analyzed.

RESULTS

There were 317 male and 81 female patients, with a median age of 64. For 66.1% of the patients, peak hs-TnT occurred at the 24th hour after OPCABG, regardless of the groups divided by different factors. In total, the hs-TnT values were much higher in male group (P = 0.035), in patients who need 5 or more bypass grafts (P = 0.035) and in patients with high-risk EuroSCORE II assessment (P = 0.013). However, we failed to find any significant differences between different age groups (P = 0.129) or among different coronary heart disease classifications (P = 0.191).

CONCLUSIONS

The hs-TnT values were affected by various factors and culminated around the first 24 h following OPCABG. It may provide some useful information for future clinical studies of myocardial biomarkers after OPCABG.

Postoperative interleukin-8 levels are related to the duration of coronary artery bypass grafting surgery and predict in-hospital postsurgical complications

Introduction: The magnitude of the very early coronary artery bypass grafting (CABG)-related inflammatory response has been shown to influence post-CABG outcomes. However, the dynamics of the systemic inflammatory response to CABG beyond the very early postoperative phase and its relevance to clinical outcomes are not fully understood.

Methods: Circulating levels of several inflammatory markers were determined in 30 consecutive patients undergoing elective isolated on-pump CABG one day prior (D0-1), and 2 (D2) and 5 days post-CABG.

Results: CABG was associated with a significant increase in all studied inflammatory marker levels (all p<0.05 for D2 versus D0-1). D2 post-CABG IL-6 and IL-8 levels were both significantly positively correlated with extracorporeal circulation (ECC) and aortic clamping (AC) times (all p<0.05), whereas a weaker correlation was observed between D2 post-CABG IL-8 levels and total surgery time (r=0.42, p=0.02). In multiple regression analysis, D2 IL-8 levels independently predicted post-CABG kidney (p= 0.02) and liver (p = 0.04) dysfunction, as well as a sum of post-CABG major complications ≥2 (p = 0.04).

Conclusions: In this prospective study, longer duration of cardiopulmonary bypass caused a larger post-CABG inflammatory surge, whereas the duration of total CABG surgery had a less significant effect. IL-8 hyperresponders had greater risk of developing kidney and liver dysfunction and presented more major post-CABG complications. These data suggest that targeting the IL-8 pathway using antiinflammatory agents, or simply by shortening the duration of cardiopulmonary bypass could improve the in-hospital post-CABG outcomes in this population.

Remote Ischemic Preconditioning has a Cardioprotective Effect in Children in the Early Postoperative Phase: A Meta-Analysis of Randomized Controlled Trials

In this updated meta-analysis, we assessed the cardioprotective effect of remote ischemic preconditioning (RIPC) in pediatric patients undergoing congenital heart surgery. A total of 9 randomized controlled trials (RCTs) involving 793 pediatric patients under 18 years old were identified. RIPC obviously reduced the release of troponin I at 6 h after surgery [standard mean difference (SMD) -0.59, 95% confidence interval (CI) -1.14 to -0.04; p = 0.03], mitigated the inotropic scores within 4-6 h (SMD -0.43, 95% CI -0.72 to -0.14; p = 0.004) and within 12 h (SMD -0.26, 95% CI -0.50 to -0.02; p = 0.03) and shortened the ventilator support time (SMD -0.28, 95% CI -0.49 to -0.07; p = 0.01) as well as the duration of intensive care unit (ICU) stay (SMD -0.21, 95% CI -0.35 to -0.06; p = 0.004). Our meta-analysis determined that RIPC had cardioprotective effects in the early postoperative phase. Additional RCTs focused on the cardiac benefits from RIPC in pediatric patients are warranted.

Prognostic Value of Early Postoperative Troponin T in Patients Undergoing Coronary Artery Bypass Grafting

BACKGROUND

Cardiac troponin T (cTnT) is elevated after coronary artery bypass grafting surgery. The aim of this study was to determine the association between cTnT elevations between 6 and 12 hours after coronary artery bypass grafting and in-hospital outcome.

METHODS AND RESULTS

We prospectively studied 1722 patients undergoing isolated coronary artery bypass grafting. We assessed the association between conventional cTnT (749 patients) and high-sensitivity cTnT (hs-cTnT; 973 patients) 6 to 12 hours postoperatively with in-hospital major adverse cardiac or cerebrovascular events (MACCE), a composite of all-cause death, myocardial infarction, or stroke. The prespecified secondary outcome was a safety composite of MACCE, resuscitation, intensive care unit readmission or admission ≥48 hours, inotrope or vasopressor use ≥24 hours, or new-onset renal insufficiency. Among patients with a conventional cTnT measurement, 92 experienced a MACCE (12%) and 146 experienced a safety composite event (19%). Likewise, for hs-cTnT, 114 experienced a MACCE (12%) and 153 experienced a safety composite event (16%). Compared with cTnT ≤200 ng/L, each 200-ng/L increment in cTnT was associated with a monotonous increase in the odds of MACCE and the safety composite outcome. Conventional and hs-cTnT demonstrated moderate discrimination for MACCE (areas under the fitted receiver operating characteristics curve, 0.72 and 0.77 for conventional and hs-cTnT, respectively) and the safety composite outcome (areas under the fitted receiver operating characteristics curve, 0.66 and 0.74 for conventional and hs-cTnT, respectively) and resulted in improved prognostic performance when added to the EuroSCORE. At a cutoff of 800 ng/L, conventional and hs-cTnT provided clinically relevant power to rule in MACCE and the safety composite outcome.

CONCLUSIONS

cTnT levels assessed between 6 and 12 hours after coronary artery bypass grafting identify patients at increased risk of MACCE or other complications.

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.

Postoperative High-Sensitivity Troponin and Its Association With 30-Day and 12-Month, All-Cause Mortality in Patients Undergoing On-Pump Cardiac Surgery

BACKGROUND

Troponin T is a predictor of cardiac morbidity and mortality after cardiac surgery with most data examining fourth generational troponin T assays. We hypothesize that postoperative high-sensitivity troponin T (hsTnT) measured in increments of the upper limit of the norm independently predicts 30-day all-cause mortality.

METHODS

We included consecutive patients undergoing on-pump cardiac surgery from February 2010 to March 2012 in a prospective cohort that measured hsTnT at 0600 of the first and second postoperative day. Our primary end point was 30-day, all-cause mortality. The secondary end point was 12-month, all-cause mortality in patients surviving the first 30 days. We divided hsTnT into 5 predetermined categorizes based on the upper limit of the norm (ULN). We used Cox regression to examine an association of hsTnT independent of the EuroSCORE II at both 30 days as well as at 12 months in patients surviving the first 30 days. We assessed the area under the receiver operating characteristics curve and the net reassignment improvement for examining the benefit of adding of hsTnT to the EuroSCORE II for prognostication and restratification of 30-day, all-cause mortality.

RESULTS

We included 1122 of 1155 eligible patients (75% male; mean age 66 ± 11 years). We observed 58 (5.2%) deaths at 30 days and another 35 (3.4%) deaths at 12 months in patients surviving 30 days. HsTnT categorized by ULN exhibited a graded response for the mortality. Furthermore, hsTnT remained an independent predictor of all-cause mortality at 30 days (adjusted hazard ratio 1.019 [1.014-1.024] per 10-fold increase in ULN) as well as at 12 months (adjusted hazard ratio 1.019 [1.007-1.032]) in patients surviving the first 30 days. The addition of hsTnT to the EuroSCORE II significantly increased the area under the receiver operating characteristics curve (area under curve: 0.816 [95% confidence interval, 0.754-0.878] versus area under curve: 0.870 [95% confidence interval, 0.822-0.917], respectively; P = .012). Finally, adding hsTnT to the EuroSCORE II improved restratification by the net reassignment improvement, primarily by improving rule-out of events.

CONCLUSIONS

This analysis suggests that, similar to previous assays, higher postoperative concentrations of hsTnT are independently associated with all-cause mortality in patients undergoing on-pump cardiac surgery.

Heart-Type Fatty Acid Binding Protein and Ischemia-Modified Albumin for Detection of Myocardial Infarction After Coronary Artery Bypass Graft Surgery

BACKGROUND

Heart-type fatty acid binding protein (hFABP) and ischemia-modified albumin (IMA) have been put forward as novel biomarkers to detect myocardial injury shortly after onset of ischemia. We compared hFABP and IMA with cardiac troponin I (cTnI) for speed and reliability in the diagnosis of perioperative myocardial infarction (PMI) after coronary artery bypass graft surgery (CABG).

METHODS

In all, 210 consecutive patients undergoing isolated CABG with cardiopulmonary bypass were enrolled in a prospective study. Blood samples were taken perioperatively and throughout the first 72 hours after surgery; clinical data and events were recorded. In cohort A, serum concentrations of hFABP and cTnI were measured using a combined quantitative bedside assay. In cohort B, IMA and cTnI serum concentrations were measured using an albumin cobalt binding test. Perioperative myocardial infarction was defined using a cTnI cutoff of greater than 10.5 ng/mL occurring within 24 hours of CABG or new electrocardiographic changes.

RESULTS

In cohort A, 14 patients were identified with PMI (group 1), whereas 94 had no PMI and served as controls (group 2). Both hFABP and cTnI were increased in group 1 as compared with group 2 (p < 0.001). Although cTnI did not differ before 12 hours, hFABP diverged much earlier, at 1 hour postoperatively (p < 0.001). An hFABP concentration of 20 μg/mL at 1 hour detected PMI with an area under the curve of 77.1%. In cohort B, 18 patients were identified with PMI (group 3), and 84 patients served as controls (group 4). No difference in cTnI values could be observed between the groups until 12 hours postoperatively. Ischemia-modified albumin failed to differentiate at any postoperative time point; the low discriminative power of IMA was confirmed with an area under the curve of 53.3% at 1 hour, 48.5% at 6 hours, and 39.3% at 12 hours postoperatively.

CONCLUSIONS

Heart-type fatty acid binding protein is a sensitive and rapid biomarker that detected PMI reliably at 1 hour after CABG, much earlier than cTnI. The diagnostic value of IMA for detection of PMI appears to be very limited in this setting.

Remote Ischemic Conditioning: A Clinical Trial’s Update

Coronary artery disease (CAD) is the leading cause of death and disability worldwide, and early and successful restoration of myocardial reperfusion following an ischemic event is the most effective strategy to reduce final infarct size and improve clinical outcome. This process can, however, induce further myocardial damage, namely acute myocardial ischemia-reperfusion injury (IRI) and worsen clinical outcome. Therefore, novel therapeutic strategies are required to protect the myocardium against IRI in patients with CAD. In this regard, the endogenous cardioprotective phenomenon of “ischemic conditioning,” in which the heart is put into a protected state by subjecting it to one or more brief nonlethal episodes of ischemia and reperfusion, has the potential to attenuate myocardial injury during acute IRI. Intriguingly, the heart can be protected in this manner by applying the “ischemic conditioning” stimulus to an organ or tissue remote from the heart (termed remote ischemic conditioning or RIC). Furthermore, the discovery that RIC can be noninvasively applied using a blood pressure cuff on the upper arm to induce brief episodes of nonlethal ischemia and reperfusion in the forearm has greatly facilitated the translation of RIC into the clinical arena. Several recently published proof-of-concept clinical studies have reported encouraging results with RIC, and large multicenter randomized clinical trials are now underway to investigate whether this simple noninvasive and virtually cost-free intervention has the potential to improve clinical outcomes in patients with CAD. In this review article, we provide an update of recently published and ongoing clinical trials in the field of RIC.

Esmolol before cardioplegia and as cardioplegia adjuvant reduces cardiac troponin release after cardiac surgery. A randomized trial

Background:

Cardioplegic solutions are the standard in myocardial protection during cardiac surgery, since they interrupt the electro-mechanical activity of the heart and protect it from ischemia during aortic cross-clamping. Nevertheless, myocardial damage has a strong clinical impact. We tested the hypothesis that the short-acting beta-blocker esmolol, given immediately before cardiopulmonary bypass and as a cardioplegia additive, would provide an extra protection to myocardial tissue during cardiopulmonary bypass by virtually reducing myocardial activity and, therefore, oxygen consumption to zero.

Materials and methods:

This was a single-centre, double-blind, placebo-controlled, parallel-group phase IV trial. Adult patients undergoing elective valvular and non-valvular cardiac surgery with end diastolic diameter >60 mm and ejection fraction <50% were enrolled. Patients were randomly assigned to receive either esmolol, 1 mg/kg before aortic cross-clamping and 2 mg/kg with Custodiol® crystalloid cardioplegia or equivolume placebo. The primary end-point was peak postoperative troponin T concentration. Troponin was measured at Intensive Care Unit arrival and at 4, 24 and 48 hours. Secondary endpoints included ventricular fibrillation after cardioplegic arrest, need for inotropic support and intensive care unit and hospital stay.

Results:

We found a reduction in peak postoperative troponin T, from 1195 ng/l (690–2730) in the placebo group to 640 ng/l (544–1174) in the esmolol group (p=0.029) with no differences in Intensive Care Unit stay [3 days (1-6) in the placebo group and 3 days (2-5) in the esmolol group] and hospital stay [7 days (6–10) in the placebo group and 7 days (6–12) in the esmolol group]. Troponin peak occurred at 24 hours for 12 patients (26%) and at 4 hours for the others (74%). There were no differences in other secondary end-points.

Conclusions:

Adding esmolol to the cardioplegia in high-risk patients undergoing elective cardiac surgery reduces peak postoperative troponin levels. Further investigation is necessary to assess esmolol effects on major clinical outcomes.

microRNA assays for acute coronary syndromes

microRNAs are promising biomarkers for diverse cardiovascular diseases. While quantification of the small non-coding RNAs is routinely performed in the research laboratory, clinical-grade assessment of microRNAs in central laboratory environments or point-of-care testing is still in its infancy. In this review, we provide an overview on microRNAs as biomarkers for acute coronary syndromes and highlight promising technical approaches for microRNA-based assays systems.

Predictive value of high-sensitivity troponin T in addition to EuroSCORE II in cardiac surgery

OBJECTIVES

Plasma troponins, measured by fourth-generation assays, are associated with increased mortality and morbidity after cardiac surgery. They also offer predictive information in addition to EuroSCORE, a widely used risk model after cardiac surgery. However, preoperatively measured troponin has provided no additional information to postoperative values. Whether these facts hold true also for the high-sensitivity fifth-generation troponin assay and the better calibrated risk model, EuroSCORE II, is unknown. We hypothesized that preoperative and/or postoperative high-sensitivity troponin T (hs-TnT) would increase the predictive value of EuroSCORE II.

METHODS

Consecutive coronary artery bypass grafting (CABG) and other cardiac surgical patients were prospectively enrolled in a university hospital. Plasma samples and EuroSCORE II variables were collected. The primary and secondary end-points were 180-day mortality and any major adverse event within 30 days, and 961-day mortality. The data were analysed by Kaplan-Meier survival curves, regression analyses, receiver operator characteristic curves and decision curve analysis.

RESULTS

Mortality rates in 180 days were 3.5% (15/428) in CABG and 6.4% (14/220) in other cardiac surgical patients. Survival curves differed only in patients with not only high postoperative hs-TnT value (>500 ng/l), but also high preoperative hs-TnT value (>14 ng/l), compared with patients with both hs-TnT values low. Adding hs-TnT to EuroSCORE II improved the prediction of 180-day mortality in other cardiac surgical patients (maximum net benefit of 1.5%), but not in CABG patients. Regarding major adverse events, adding hs-TnT to EuroSCORE II improved the prediction in both CABG patients and other cardiac surgical patients (maximum net benefits of 3 and 7%).

CONCLUSIONS

Elevated postoperative hs-TnT was predictive of mortality only when combined with elevated preoperative hs-TnT. Hs-TnT measurements added information to the EuroSCORE II regarding major adverse events in all cardiac surgical patients and regarding 180-day mortality in non-CABG patients.

Kinetics of Highly Sensitive Troponin T after Cardiac Surgery

Perioperative myocardial infarction (PMI) confers a considerable risk in cardiac surgery settings; finding the ideal biomarker seems to be an ideal goal. Our aim was to assess the diagnostic accuracy of highly sensitive troponin T (hsTnT) in cardiac surgery settings and to define a diagnostic level for PMI diagnosis. This was a single-center prospective observational study analyzing data from all patients who underwent cardiac surgeries. The primary outcome was the diagnosis of PMI through a specific level. The secondary outcome measures were the lengths of mechanical ventilation (LOV), stay in the intensive care unit (LOSICU), and hospitalization. Based on the third universal definition of PMI, patients were divided into two groups: no PMI (Group I) and PMI (Group II). Data from 413 patients were analyzed. Nine patients fulfilled the diagnostic criteria of PMI, while 41 patients were identified with a 5-fold increase in their CK-MB (≥120 U/L). Using ROC analysis, a hsTnT level of 3,466 ng/L or above showed 90% sensitivity and 90% specificity for the diagnosis of PMI. Secondary outcome measures in patients with PMI were significantly prolonged. In conclusion, the hsTnT levels detected here paralleled those of CK-MB and a cut-off level of 3466 ng/L could be diagnostic of PMI.

A retrospective analysis of myocardial preservation techniques during coronary artery bypass graft surgery: are we protecting the heart?

Background

Retrograde perfusion into coronary sinus during coronary artery bypass graft (CABG) surgery reduces the need for cardioplegic interruptions and ensures the distribution of cardioplegia to stenosed vessel territories, therefore enhancing the delivery of cardioplegia to the subendocardium. Peri-operative myocardial injury (PMI), as measured by the rise of serum level of cardiac biomarkers, has been associated with short and long-term clinical outcomes. We conducted a retrospective analysis to investigate whether the combination of antegrade and retrograde techniques of cardioplegia delivery is associated with a reduced PMI than that observed with the traditional methods of myocardial preservation.

Methods

Fifty-four consecutive patients underwent CABG surgery using either antegrade cold blood cardioplegia (group 1, n = 28) or cross-clamp fibrillation (group 2, n = 16) or antegrade retrograde warm blood cardioplegia (group 3, n = 10). The study primary end-point was PMI, evaluated with total area under the curve (AUC) of high-sensitivity Troponin-T (hsTnT), measured pre-operatively and at 6, 12, 24, 48 and 72 hours post-surgery. Secondary endpoints were acute kidney injury (AKI) and inotrope scores, length of intensive care unit (ICU) and hospital stay, new onset atrial fibrillation (AF) and clinical outcomes at 6 weeks (death, non-fatal myocardial infarction, coronary artery revascularization, stroke).

Results

There was evidence that mean total AUC of hsTnT was different among the three groups (P = 0.050). In particular mean total AUC of hsTnT was significantly lower in group 3 compared to both group 1 (-16.55; 95% CI: -30.08, -3.01; P = 0.018) with slightly weaker evidence of a lower mean hsTnT in group 3 when compared to group 2 (-15.13; 95% CI -29.87, -0.39; P = 0.044). There was no evidence of a difference when comparing group 2 to group 1 (-1.42,; 95% CI: -12.95, 10.12, P = 0.806).

Conclusions

Our retrospective analysis suggests that, compared to traditional methods of myocardial preservation, antegrade retrograde cardioplegia may reduce PMI in patients undergoing first time CABG surgery.

Electronic supplementary material

The online version of this article (doi:10.1186/s13019-014-0184-7) contains supplementary material, which is available to authorized users.

Changes of cardiac troponin I and operative mortality of coronary artery bypass

Background

Recently, cardiac troponin I has been used to detect myocardial injury because of its superior cardiac specificity. However, there has been debate about the appropriate timing and cutoff level of cardiac troponin I to detect perioperative myocardial injury after coronary artery bypass grafting. The objective of this study was to define the relationship between operative mortality and changes in cardiac troponin I after isolated coronary artery bypass.

Patients and methods

A retrospective analysis was carried out on data of 218 isolated coronary artery bypass patients who were operated on between June 2009 and February 2012. All patients followed an institutional perioperative management protocol that included 6 cardiac troponin I measurements (preoperatively and 0, 12, 24, 36, and 48 h after coronary artery bypass). According to the patterns of cardiac troponin I, the patient cohort was divided into 2 groups. Group 1 was patients in whom cardiac troponin I levels decreased 24 h after the operation, and group 2 comprised the patients with cardiac troponin I levels that did not decrease or even increased after 24 h.

Results

The operative mortality was 4.1% (9/218). Group 2 showed significantly higher mortality (5/25, 20%) than group 1 (4/193, 2.1%).

Conclusion

An elevated cardiac troponin I level is common after coronary artery bypass. A persistently high level of cardiac troponin I after 24 h is an important predictor of operative mortality after coronary artery bypass surgery.

The role of remote ischemic preconditioning in organ protection after cardiac surgery: a meta-analysis

BACKGROUND

Remote ischemic preconditioning (RIPC) appears to protect distant organs from ischemia-reperfusion injury. We undertook meta-analysis of clinical studies to evaluate the effects of RIPC on organ protection and clinical outcomes in patients undergoing cardiac surgery.

METHODS

A review of evidence for cardiac, renal, and pulmonary protection after RIPC was performed. We also did meta-regressions on RIPC variables, such as duration of ischemia, cuff pressure, and timing of application of preconditioning. Secondary outcomes included length of hospital and intensive care unit stay, duration of mechanical ventilation, and mortality at 30 days.

RESULTS

Randomized control trials (n = 25) were included in the study for quantitative analysis of cardiac (n = 16), renal (n = 6), and pulmonary (n = 3) protection. RIPC provided statistically significant cardiac protection (standardized mean difference [SMD], -0.77; 95% confidence interval [CI], -1.15, -0.39; Z = 3.98; P < 0.0001) and on subgroup analysis, the protective effect remained consistent for all types of cardiac surgical procedures. However, there was no evidence of renal protection (SMD, 0.74; 95% CI, 0.53, 1.02; Z = 1.81; P = 0.07) or pulmonary protection (SMD, -0.03; 95% CI, -0.56, 0.50; Z = 0.12; P = 0.91). There was no statistical difference in the short-term clinical outcomes between the RIPC and control groups.

CONCLUSIONS

RIPC provides cardiac protection, but there is no evidence of renal or pulmonary protection in patients undergoing cardiac surgery using cardiopulmonary bypass. Larger multicenter trials are required to define the role of RIPC in surgical practice.

Early troponin T and prediction of potentially correctable in-hospital complications after coronary artery bypass grafting surgery

Background

Peak levels of troponin T (TnT) reliably predict morbidity and mortality after cardiac surgery. However, the therapeutic window to manage CABG-related in-hospital complications may close before the peak is reached. We investigated whether early TnT levels correlate as well with complications after coronary artery bypass grafting (CABG) surgery.

Methods

A 12 month consecutive series of patients undergoing elective isolated CABG procedures (mini-extra-corporeal circuit, Cardioplegic arrest) was analyzed. Logistic regression modeling was used to investigate whether TnT levels 6 to 8 hours after surgery were independently associated with in-hospital complications (either post-operative myocardial infarction, stroke, new-onset renal insufficiency, intensive care unit (ICU) readmission, prolonged ICU stay (>48 hours), prolonged need for vasopressors (>24 hours), resuscitation or death).

Results

A total of 290 patients, including 36 patients with complications, was analyzed. Early TnT levels (odds ratio (OR): 6.8, 95% confidence interval (CI): 2.2-21.4, P=.001), logistic EuroSCORE (OR: 1.2, 95%CI: 1.0-1.3, P=.007) and the need for vasopressors during the first 6 postoperative hours (OR: 2.7, 95%CI: 1.0-7.1, P=.05) were independently associated with the risk of complications. With consideration of vasopressor use during the first 6 postoperative hours, the sum of specificity (0.958) and sensitivity (0.417) of TnT for subsequent complications was highest at a TnT cut-off value of 0.8 ng/mL.

Conclusion

Early TnT levels may be useful to guide ICU management of CABG patients. They predict clinically relevant complications within a potential therapeutic window, particularly in patients requiring vasopressors during the first postoperative hours, although with only moderate sensitivity.

Hyperkalemic cardioplegia for adult and pediatric surgery: end of an era?

Despite surgical proficiency and innovation driving low mortality rates in cardiac surgery, the disease severity, comorbidity rate, and operative procedural difficulty have increased. Today's cardiac surgery patient is older, has a "sicker" heart and often presents with multiple comorbidities; a scenario that was relatively rare 20 years ago. The global challenge has been to find new ways to make surgery safer for the patient and more predictable for the surgeon. A confounding factor that may influence clinical outcome is high K(+) cardioplegia. For over 40 years, potassium depolarization has been linked to transmembrane ionic imbalances, arrhythmias and conduction disturbances, vasoconstriction, coronary spasm, contractile stunning, and low output syndrome. Other than inducing rapid electrochemical arrest, high K(+) cardioplegia offers little or no inherent protection to adult or pediatric patients. This review provides a brief history of high K(+) cardioplegia, five areas of increasing concern with prolonged membrane K(+) depolarization, and the basic science and clinical data underpinning a new normokalemic, "polarizing" cardioplegia comprising adenosine and lidocaine (AL) with magnesium (Mg(2+)) (ALM™). We argue that improved cardioprotection, better outcomes, faster recoveries and lower healthcare costs are achievable and, despite the early predictions from the stent industry and cardiology, the "cath lab" may not be the place where the new wave of high-risk morbid patients are best served.

Remote ischemic preconditioning: the surgeon's perspective

Since cardiac surgery began, surgeons have aimed to find methods of minimizing myocardial injury resulting from ischemia and reperfusion. The concept of somehow conditioning the heart in order to attenuate ischemia and reperfusion-related injury has evolved in cardiovascular research over decades, from ischemic preconditioning and postconditioning to, more recently, remote ischemic preconditioning (and postconditioning). Although many strategies have proven to be beneficial in the experimental arena, a few have been successfully translated into clinical practice. Remote ischemic preconditioning, with the use of brief episodes of ischemia and reperfusion of vascular territories remote from the heart, has been shown convincingly to decrease myocardial injury. To date, the translation of this powerful innate mechanism of myocardial and/or multiorgan protection from the animal lab to the operating theatre, using transient occlusion of blood flow to the upper limb with a blood-pressure cuff before cardiac surgery, has shown promising results, with several proof-of-principle and first randomized controlled clinical trials reporting benefits for patients undergoing cardiac surgery. If the efficacy of remote ischemic preconditioning can be conclusively proven, the clinical applications in cardiac surgery could be almost infinite, providing multiorgan protection in various surgical scenarios.

The emerging application of remote ischemic conditioning in the clinical arena

Remote ischemic conditioning (RIC) is an intervention, in which intermittent episodes of ischemia and reperfusion in an organ or tissue distant from the target organ requiring protection, provide armour against lethal ischemia-reperfusion injury. Although the exact mechanisms underlying the protection mediated through RIC have not been clearly established, the release of humoral factors and the activation of neural pathways have been implicated. There is now clinical evidence suggesting that this form of protection can be induced by a simple, noninvasive, and cost-effective procedure such as inflation and deflation of a blood pressure cuff and that this intervention provides increased organ protection in a variety of clinical scenarios, for example, in myocardial infarction. Here we provide an overview of the history and evolution of RIC, the potential mechanisms underlying its protective effects, and published randomized clinical trials in cardiovascular procedures.

Troponin T is a better predictor than creatine kinase-MB of long-term mortality after coronary artery bypass graft surgery

BACKGROUND

Elevations of creatine kinase-MB (CK-MB) and cardiac troponin T (cTnT) have an uncertain long-term prognostic value after coronary artery bypass graft (CABG) surgery. We aimed to test the hypothesis that CK-MB and cTnT are predictors of long-term survival after CABG and to assess which of these 2 biomarkers is the better predictor.

METHODS

A total of 1,350 consecutive patients undergoing isolated on-pump CABG had CK-MB and cTnT measured at 7, 20, and 44 hours, postoperatively. The end point was all-cause mortality, and during the median follow-up time of 6.1 years, 207 patients (15.3%) died.

RESULTS

Both peak CK-MB and peak cTnT independently predicted long-term mortality (hazard ratio [HR] 1.003, 95% confidence interval [CI] 1.001-1.005, P = .007, and HR 1.31, 95% CI 1.17-1.46, P <.001, respectively) when analyzed in separate multivariate Cox models, adjusting for baseline demographic characteristics and perioperative risk factors. However, when analyzed simultaneously in the same Cox model, cTnT was a significant predictor (HR 1.31, 95% CI 1.13-1.51, P <.001), whereas CK-MB was not (P = .99). Similar results were found when the biomarkers were analyzed together in a Cox model adjusting for European System for Cardiac Operative Risk Evaluation. The differences in mortality between the biomarker groups were consistent also when analyzing strict quartiles of peak values of CK-MB and cTnT (P = .81 and P = .001, respectively).

CONCLUSIONS

Both CK-MB and cTnT are predictors of mortality after CABG surgery; however, our data suggest that cTnT is a better predictor of long-term mortality after CABG surgery than CK-MB.

A review of troponins in ischemic heart disease and other conditions

Measuring cardiac troponin (cTn) I and T levels is currently considered to be a cornerstone for making the diagnosis of acute coronary syndrome (ACS).Based on current literature, cTnI and cTnT are known to be very sensitive and specific for myocardial damage, regardless of the underlying cause. Lately, it has been found that cTns can be elevated and reflect worse prognoses in many situations where ACS is excluded. Such information can affect the validity of cTns as markers for ACS without classic symptoms. This may call for a revision of the troponin cutoff values to make a diagnosis of ACS. Furthermore, it opens a new field of study to determine appropriate management of patients with elevated cTn levels in whom ACS has been excluded.

Early elevation of cardiac troponin I is predictive of short-term outcome in neonates and infants with coronary anomalies or reduced ventricular mass undergoing cardiac surgery

OBJECTIVE

The present study aimed to assess the usefulness of routine monitoring of cardiac troponin I concentrations within 24 hours of surgery (cTn-I<24h) in neonates and infants undergoing cardiac surgery.

METHODS

The added predictive ability of a high peak cTn-I<24h (within the upper quintile per procedure) for a composite outcome, including 30-day mortality and severe morbidity, was assessed retrospectively. The predicted risk for the composite outcome was estimated from a logistic regression model including preoperative and intraoperative variables. Adding a high peak cTn-I<24h to the risk model resulted in reclassification of the predicted risk. It also allowed quantification of the improvement in reclassification and discrimination by the difference between c-indexes, the Net Reclassification and the Integrated Discrimination Indexes (NRI and IDI).

RESULTS

Overall, 1023 consecutive patients were included. Adding a high peak cTn-I<24h to the model resulted in no improvement in reclassification or discrimination in the overall population (difference between c-indexes: 0.011 [-0.004 to 0.029], NRI = 0.06, P = .22, IDI = 0.02, P = .06), except in a subgroup of patients undergoing the arterial switch operation with or without ventricular septal defect closure and/or aortic arc repair, anomalous origin of the left coronary artery from the pulmonary artery repair, truncus arteriosus repair, Norwood procedure, and Sano modification, in whom NRI = 0.23 (P = .005) and IDI = 0.05 (P < .001).

CONCLUSIONS

Patients with coronary anomalies and patients with reduced ventricular mass should benefit from the routine monitoring of cTn-I concentrations after surgery for congenital cardiac disease.

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.

Effect of remote ischemic preconditioning on clinical outcomes in patients undergoing coronary artery bypass graft surgery (ERICCA): rationale and study design of a multi-centre randomized double-blinded controlled clinical trial

BACKGROUND

Novel cardioprotective strategies are required to improve clinical outcomes in high risk patients undergoing coronary artery bypass graft (CABG) ± valve surgery. Remote ischemic preconditioning (RIC), in which brief episodes of non-lethal ischemia and reperfusion are applied to the arm or leg, has been demonstrated to reduce perioperative myocardial injury following CABG ± valve surgery. Whether RIC can improve clinical outcomes in this setting is unknown and is investigated in the effect of remote ischemic preconditioning on clinical outcomes (ERICCA) trial in patients undergoing CABG surgery. (ClinicalTrials.gov Identifier: NCT01247545).

METHODS

The ERICCA trial is a multicentre randomized double-blinded controlled clinical trial which will recruit 1,610 high-risk patients (Additive Euroscore ≥ 5) undergoing CABG ± valve surgery using blood cardioplegia via 27 tertiary centres over 2 years. The primary combined endpoint will be cardiovascular death, non-fatal myocardial infarction, coronary revascularization and stroke at 1 year. Secondary endpoints will include peri-operative myocardial and acute kidney injury, intensive care unit and hospital stay, inotrope score, left ventricular ejection fraction, changes of quality of life and exercise tolerance. Patients will be randomized to receive after induction of anesthesia either RIC (4 cycles of 5 min inflation to 200 mmHg and 5 min deflation of a blood pressure cuff placed on the upper arm) or sham RIC (4 cycles of simulated inflations and deflations of the blood pressure cuff).

IMPLICATIONS

The findings from the ERICCA trial have the potential to demonstrate that RIC, a simple, non-invasive and virtually cost-free intervention, can improve clinical outcomes in higher-risk patients undergoing CABG ± valve surgery.

Failure to recapture cardioprotection with high-dose atorvastatin in coronary artery bypass surgery: a randomised controlled trial

The acute administration of atorvastatin has been reported to reduce myocardial infarct size in animal studies. However, this cardioprotective effect is lost with the chronic administration of atorvastatin, although it can be recaptured by administering an acute high-dose of atorvastatin. We hypothesised that pre-treatment with high-dose atorvastatin, on a background of chronic standard 'statin' therapy, would reduce myocardial injury in patients undergoing elective coronary artery bypass graft (CABG) surgery. One hundred and one consenting patients undergoing elective CABG surgery at a single tertiary cardiac centre were recruited into two randomised controlled, single-blinded clinical studies. Study 1: 45 patients were randomised to receive either 160 mg of atorvastatin 2 h preoperatively and 24 h following surgery or their standard statin therapy. Study 2: 56 patients were randomised to receive either 160 mg of atorvastatin 12 h preoperatively and 24 h following surgery or their standard statin therapy. Blood samples for troponin T and creatine kinase were taken prior to surgery and then at 6, 12, 24, 48 and 72 h post-surgery. Cardiac enzyme levels at each time point and the total area-under curve (AUC) were calculated. The group characteristics and surgical methods were well matched. High-dose atorvastatin was not associated with any significant side effects. There was no significant difference in serum troponin T or creatine kinase in either study at each time point or over 72 h. Study 1: AUC, troponin T: atorvastatin 29.6 ± 34.8 μg/L versus control 25.0 ± 22.0 μg/L:P > 0.05. Creatine kinase: atorvastatin 33,544 ± 20,063 IU/L versus control 30,620 ± 10,776 IU/L:P > 0.05. Study 2: AUC, troponin T: atorvastatin 21.8 ± 14.3 μg/L versus control 20.9 ± 8.7 μg/L:P > 0.05. Creatine kinase: atorvastatin 36,262 ± 28,821 IU/L versus control 33,448 ± 14,984:P > 0.05. There were no differences in postoperative outcomes. We report that the administration of high-dose atorvastatin to low risk patients undergoing elective CABG surgery, who are already on standard dose 'statin' therapy is safe, but does not further reduce perioperative myocardial injury.

The therapeutic potential of ischemic conditioning: an update

Novel approaches are required to improve clinical outcomes in patients with coronary heart disease (CHD). Ischemic conditioning--the practice of applying brief episodes of nonlethal ischemia and reperfusion to confer protection against a sustained episode of lethal ischemia and reperfusion injury--is one potential therapeutic strategy. Importantly, the protective stimulus can be applied before (ischemic preconditioning) or after (ischemic perconditioning) onset of the sustained episode of lethal ischemia, or even at the onset of myocardial reperfusion (ischemic postconditioning). Furthermore, the protective stimulus can be applied noninvasively by placing a blood-pressure cuff on an upper or lower limb to induce brief episodes of nonlethal ischemia and reperfusion (remote ischemic conditioning), a finding that has greatly facilitated the translation of ischemic conditioning to various clinical settings. In addition to mechanical approaches, elucidation of the signal-transduction pathways underlying ischemic conditioning has identified several novel targets for pharmacological conditioning. This Review highlights findings from proof-of-concept clinical studies conducted in the past 5-6 years, in which the therapeutic potential of ischemic and pharmacological conditioning has been realized. Large, randomized, controlled trials are now required to determine whether pharmacological and ischemic conditioning improve clinical end points and outcomes in patients with CHD.