Myocardial injury after off-pump coronary artery bypass grafting operation

Factors causing prolonged mechanical ventilation and peri-operative morbidity after robot-assisted coronary artery bypass graft surgery

Robot-assisted coronary artery bypass graft [robot-assisted (coronary artery bypass grafting (CABG)] surgery is the latest treatment for coronary artery disease. However, the surgery extensively affects cardiac and pulmonary function, and the risk factors associated with peri-operative morbidity, including prolong mechanical ventilation (PMV), have not been fully examined. In this retrospective cohort study, a total of 382 patients who underwent robot-assisted internal mammary artery harvesting with mini-thoracotomy direct-vision bypass grafting surgery (MIDCABG) from 2005 to 2012 at our tertiary care hospital were included. The definition of PMV was failure to wean from mechanical ventilation more than 48 h after the surgery. Risk factors for PMV, and peri-operative morbidity and mortality were analyzed with a multivariate logistic regression model. Forty-three patients (11.3%) developed PMV after the surgery, and the peri-operative morbidity and mortality rates were 38 and 2.6%, respectively. The risk factors for PMV were age, left ventricular ejection fraction (LVEF), the duration of one-lung ventilation for MIDCABG (beating time), and peak airway pressure at the end of the surgery. Furthermore, age and anesthesia time were found to be independent risk factors for peri-operative morbidity, whereas age, LVEF, and anesthesia time were the risk factors for peri-operative mortality. These findings may help physicians to properly choose patients for this procedure, and provide more attention to patients with higher risk after surgery to achieve better clinical outcomes.

The impact of off-pump surgery in end-organ function: practical end-points

Most surgeons perform coronary bypass surgery with the aid of cardiopulmonary bypass, which inflicts a massive systemic inflammatory response to the body leading to adverse clinical outcome. In an attempt to make CABG less invasive, interest have been diverted to the off pump technique.The current review attempts to bring an insight onto the last ten years knowledge on the off-pump impact in end organ function, with an aim to draw some clear conclusions in order to allow practitioners to reflect on the subject.

The Effectiveness of Preoperative Trimetazidine on Myocardial Preservation in Coronary Artery Bypass Graft Patients: A Systematic Review and Meta-Analysis

Background: Coronary artery bypass grafting (CABG) is a key and effective surgical treatment modality for coronary artery disease. Unfortunately, ischemia-reperfusion injury during and after CABG can lead to reversible and irreversible myocardial damage. Trimetazidine [1-(2,3,4-trimethoxybenzyl)piperazine dihydrochloride] is a metabolic anti-ischemic agent with demonstrated cardioprotective effects; however, its effects with respect to myocardial preservation in CABG patients remain unclear. Methods: We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to investigate the effectiveness of myocardial preservation of preoperative trimetazidine therapy in CABG patients by assessing the postoperative levels of several blood-based biochemical markers of myocardial injury, including creatine kinase (CK), creatine kinase-muscle and brain (CK-MB), creatine phosphokinase (CPK), troponin T (TnT) and troponin I (TnI). The RCTs were classified into two subgroup analyses by the timing of sample collection (either ≤12 or >12 h after CABG). Results: Six RCTs were finally included in the meta-analysis. The pooled effect sizes showed significantly lower postoperative levels of CK, CK-MB, TnT and TnI in the trimetazidine-treated CABG patients relative to control CABG patients. However, there were no significant differences in the postoperative CPK levels between trimetazidine-treated CABG patients relative to control CABG patients. In both the ≤12 and >12 h post-CABG subgroup analyses, significant differences in CK, CK-MB, TnT and TnI were detected between the trimetazidine-treated CABG patients relative to control CABG patients. Conclusions: Preoperative trimetazidine therapy appears to have a positive effect on myocardial preservation in CABG patients.

Protective effect of dexmedetomidine in coronary artery bypass grafting surgery

The aim of this study was to observe the impact of dexmedetomidine on postoperative myocardial injury in patients undergoing off-pump coronary artery bypass (OPCAB) grafting. One hundred and sixty-two patients who were undergoing OPCAB surgery were randomly divided into control and dexmedetomidine groups (groups C and Dex, respectively). Following the first vascular anastomosis grafting, the patients in group Dex received a continuous intravenous infusion of 0.2–0.5 μg/kg/h dexmedetomidine, until they were transferred to the Cardiac Surgery intensive care unit (ICU) for 12 h. Patients in group C received physiological saline intraoperatively and an intravenous infusion of 2–4 mg/kg/h isopropylphenol for postoperative sedation. Invasive arterial pressure and heart rate were continuously monitored for 5 min subsequent to entry into the operating theatre (T0), immediately following surgery (T1), 12 h post-surgery (T2), 24 h post-surgery(T3), 48 h post-surgery(T4) and 72 h post-surgery (T5). Blood samples were taken to determine the plasma levels of cardiac troponin I (cTnI) and creatine kinase-MB (CK-MB) at each time point. At 72 h post-surgery, a dynamic electrocardiogram was monitored. The blood pressure, heart rate, levels of cTnI, CK-MB, norepinephrine and cortisol, and postoperative arrhythmic events in the patients in group Dex all decreased compared with those in group C. The duration of mechanical ventilation and ICU residence time were also shorter than those in the control group (P<0.05). Dexmedetomidine reduced post-surgical myocardial injury in patients who had undergone OPCAB surgery.

Effects of remote ischemic preconditioning with postconditioning in patients undergoing off-pump coronary artery bypass surgery--randomized controlled trial

BACKGROUND

Myocardial injury is associated with an adverse outcome after off-pump coronary artery bypass graft surgery (OPCAB). The authors conducted a randomized controlled trial to evaluate whether remote ischemic preconditioning (RIPC) with remote ischemic postconditioning (RIPostC) reduces myocardial injury in patients undergoing OPCAB.

METHODS AND RESULTS

Seventy patients scheduled for OPCAB were randomly assigned to an RIPC+RIPostC group (n=35) or a control group (n=35). In the RIPC+RIPostC group, 4 cycles of 5-min ischemia and 5-min reperfusion were done on a lower limb before anastomoses (RIPC) and after anastomoses (RIPostC). RIPC+RIPostC significantly reduced postoperative serum troponin I levels (P=0.001). The area under the curve for postoperative troponin I was 48.7% lower in the RIPC+RIPostC group (median [interquartile range], 21.3 h·ng⁻¹·ml⁻¹, 16.5-53.1 h·ng⁻¹·ml⁻¹ vs. 41.5 h·ng⁻¹·ml⁻¹, 24.6-90.2 h·ng⁻¹·ml⁻¹, P=0.020). There was no significant difference in creatinine levels and PaO₂/F(i)O₂ ratios between the 2 groups.

CONCLUSIONS

RIPC+RIPostC by lower limb ischemia decreased postoperative myocardial enzyme elevation by almost half postoperatively in patients undergoing OPCAB.

The effect of remote ischaemic preconditioning on myocardial injury in patients undergoing off-pump coronary artery bypass graft surgery

In several recent clinical trials on cardiac surgery patients, remote ischaemic preconditioning (RIPC) showed a powerful myocardial protective effect. However the effect of RIPC has not been studied in patients undergoing off-pump coronary artery bypass graft surgery. We evaluated whether RIPC could induce myocardial protection in off-pump coronary artery bypass graft surgery patients. Patients undergoing elective off-pump coronary artery bypass graft surgery were randomly allocated to the RIPC (n = 65) or control group (n = 65). After induction of anaesthesia, RIPC was induced by four cycles of five-minute ischaemia and reperfusion on the upper limb using a pneumatic cuff. Anaesthesia was maintained with sevoflurane, remifentanil and vecuronium. Myocardial injury was assessed by troponin I before surgery and 1, 6, 12, 24, 48 and 72 hours after surgery. There were no statistical differences in troponin I levels between RIPC and control groups (P = 0.172). Although RIPC reduced the total amount of troponin I (area under the curve of troponin increase) by 26%, it did not reach statistical significance (RIPC group 53.2 +/- 72.9 hours x ng/ml vs control group 67.4 +/- 97.7 hours x ng/ml, P = 0.281). In this study, RIPC by upper limb ischaemia reduced the postoperative myocardial enzyme elevation in off-pump coronary artery bypass graft surgery patients, but this did not reach statistical significance. Further study with a larger number of patients may be needed to fully evaluate the clinical effect of RIPC in off-pump coronary artery bypass graft surgery patients.

Predictors of cardiac troponin release after mitral valve surgery

OBJECTIVES

Although cardiac troponin I (cTnI) measurement is used extensively as a marker of perioperative myocardial injury, limited knowledge exists in noncoronary artery bypass graft surgery.

DESIGN

Observational study.

SETTING

Single-center intensive care unit.

INTERVENTION

None.

PARTICIPANTS

One hundred eighty-five consecutive adult patients undergoing mitral valve surgery for predominant mitral regurgitation were enrolled and underwent measurement of cTnI at 24 hours after surgery.

MEASUREMENTS AND MAIN RESULTS

CTnI release after mitral valve surgery was significantly associated with an adverse outcome. The optimal cTnI value for predicting adverse outcomes was 14 ng/mL. Univariate preoperative predictors of cTnI release were prior use of diuretics (p = 0.04) or a rheumatic (p = 0.006), ischemic (p = 0.004), or myxomatous (p = 0.005) etiology to mitral disease, whereas intraoperative variables predictive of cTnI release were cross-clamp time (p = 0.005), cardiopulmonary bypass time (p < 0.001), need for mitral valve replacement (p = 0.024), number of electrical cardioversions (p = 0.03), patent foramen ovale closure (p = 0.03), tricuspid valve repair (p = 0.04), need for epinephrine/norepinephrine (p = 0.004) or intra-aortic balloon pump (p = 0.03) in the operating room; and, finally, the surgeon who performed the surgery (p = 0.014). There were no postoperative predictors of excessive cTnI release. In multivariate analysis, the only predictors of cTnI release were the cardiopulmonary bypass time (odds ratio, 1.42; confidence intervals, 1.019-1.064; p = 0.001) and the infusion of epinephrine/norepinephrine in the operating room (odds ratio, 4.002; confidence intervals, 1.238-12.929; p = 0.02).

CONCLUSIONS

After mitral surgery, the need for epinephrine/norepinephrine perioperatively and the cardiopulmonary bypass time independently predict a cTnI release significantly related to an adverse outcome.

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.