Postoperative troponin I values: insult or injury?

Postoperative cardiac troponin I as an indicator of surgical outcomes: A systematic review

INTRODUCTION

Cardiac surgeries are generally associated with high morbidity and mortality. To prevent any adverse outcomes, it is crucial to identify patients at risk of developing postoperative complications and initiate relevant therapeutic interventions. Several biomarkers are used to determine postoperative myocardial injury but they either lack sensitivity and specificity or are elevated for a short time. In this systematic review, we evaluate postoperative troponin I as a predictor of postoperative myocardial infarction, mortality, and hospital and Intensive Care Unit stay.

METHODS

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. A thorough literature search was conducted over PubMed, clinicaltrials. gov, and the Cochrane library from inception till May 24, 2022 using relevant keywords, and only articles that met the pre-defined criteria were recruited.

RESULTS

Following a comprehensive literature search, a total of 359 articles were obtained. Following a rigid screening and full-length review, only 13 studies met our inclusion criteria and were included. The recruited studies evaluated data from a total of 12,483 individuals and assessed troponin I as a predictor of at least one outcome.

CONCLUSION

Troponin I has the potential to be used as a stand-alone predictor of surgical outcomes following coronary artery bypass grafting and valvular surgeries. However, supplementing it with other markers and scores offers the best chance at timely diagnosing any complications.

Myocardial Injury After Temporary Transvenous Cardiac Pacing

INTRODUCTION

Temporary transvenous cardiac pacing (TTCP) can lead to potential penetration and occasional perforation of the right ventricular wall. No study to date has analyzed the effect of TTCP on myocardial injury by cardiac troponin (cTn) measurement. The present study was designed to investigate perioperative myocardial injury in elective TTCP in noncardiac surgical settings.

PATIENTS AND METHODS

This retrospective study investigated the data collected from August 2018 through March 2020 from 22 eligible patients who underwent elective TTCP for noncardiac procedures. The patients had a median age of 66 (50-83) years; six (27.3%) of them were women, and all of them had a baseline cTn <1 upper reference limit (URL). Cardiac biomarker assays were performed before and after TTCP, and their results were compared.

RESULTS

After TTCP, cTn > 1 URL was detected in 20 (91%, N=22) patients. Among these 22 patients, paired t-test comparing assay results before and after TTCP lead insertion showed a mean cTn elevation of 3.599 URL (95% CI: 1.566 to 5.632, P<0.01), and a mean creatine kinase-MB isoform elevation of 0.1550 URL (95% CI: -0.01239 to 0.3224, P>0.05).

CONCLUSION

The study demonstrates a high incidence of myocardial injury associated with TTCP, which should be a matter of concern for the involved physicians.

Does really previous stenting affect graft patency following CABG? A 5-year follow-up: The effect of PCI on graft survival

The aim of this study was to compare the graft patency rates among patients who had a previous history of percutaneous coronary intervention (PCI) followed by coronary artery bypass grafting surgery (CABG) with the patients who had experienced CABG surgery alone. The 69 patients who were included in the study had a history of bare metal stent implantation prior to CABG (group 1). The coronary angiography results were compared with 69 patients who had a previous history of CABG (group 2). Graft patency rates of the left anterior descending artery and circumflex anastomoses are statistically significant for both groups, whereas the right coronary artery anastomoses are not statistically significant (p = 0.008; 0.009; 0.2). Graft patency rate of LIMA-LAD anastomoses was 43.9 ± 10.8 % in group 1 and 86.2 ± 6 % in group 2 for means of 60 months (p = 0.0001) and circumflex coronary artery anastomosis is 28.9 ± 0.9 % in group 1, 65.7 ± 10.8 % in group 2 (p = 0.0001) and the right coronary artery anastomosis is 37.2 ± 13.6 % in group 1, 56.4 ± 8.9 % in group 2 (p = 0.0001). The graft patency rates of coronary arteries without previous stent implantation were higher than the patients with previous stent implantation and experienced CABG. The results suggest that prior PCI may induce atherosclerotic events in the vessel that can adversely affect graft patency after surgery.

Prognostic value of troponin I levels for predicting adverse cardiovascular outcomes in postmenopausal women undergoing cardiac surgery

BACKGROUND

Adverse cardiac events that follow cardiac surgery are an important source of perioperative morbidity and mortality for women. Troponin I provides a sensitive measure of cardiac injury, but the levels after cardiac surgery may vary between sexes. Our purpose in this study was to evaluate the prognostic value of troponin I levels for predicting cardiovascular complications in postmenopausal women undergoing cardiac surgery.

METHODS

The cohort of this study were women enrolled in a previously reported clinical trial evaluating the neuroprotective potential of 17beta-estradiol in elderly women. In that study, 175 postmenopausal women not receiving estrogen replacement therapy and scheduled to undergo coronary artery bypass graft (with or without valve surgery) were prospectively randomized to receive 17beta-estradiol or placebo in a double-blind manner beginning the day before surgery and continuing for 5 days postoperatively. Serial 12-lead electrocardiograms were performed and serum troponin I concentrations were measured before surgery, after surgery on arrival in the intensive care unit, and for the first four postoperative days. The primary end-point of the present study was major adverse cardiovascular events (MACE) defined as a Q-wave myocardial infarction, low cardiac output state or death within 30 days of surgery. The diagnosis of Q-wave myocardial infarction was made independently by two physicians blinded to treatment and patient outcomes with the final diagnosis requiring consensus. Low cardiac output state was defined as cardiac index <2.0 L x min(-1) x m(-2) for >8 h regardless of treatment.

RESULTS

Troponin I levels on postoperative day 1 were predictive of MACE (area under the receiver operator curve = 0.862). A cutoff point for troponin I of >7.6 ng/mL (95% confidence interval, 6.4-10.8) provided the optimal sensitivity and specificity for identifying patients at risk for MACE. The negative predictive value of a troponin I level for identifying a patient with a composite cardiovascular outcome was high (96%) and the positive predictive value moderate (40%). Postoperative troponin I levels were not different between women receiving perioperative 17beta-estradiol treatment compared with placebo and the frequency of MACE was not influenced by 17beta-estradiol treatment.

CONCLUSIONS

In postmenopausal women, elevated troponin I levels on postoperative day 1 are predictive of MACE. Monitoring of perioperative troponin I levels might provide a means for stratifying patients at risk for adverse cardiovascular events.

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.

Indications for angiography subsequent to coronary artery bypass grafting

BACKGROUND

Postoperative myocardial infarction is a rare, but potentially severe complication after coronary artery bypass grafting (CABG). Early markers for coronary bypass graft failure or native vessel occlusion are required, because immediate intervention could prevent major myocardial damage.

METHODS

One thousand patients with coronary artery disease consecutively underwent CABG. Postoperative coronary angiography was performed in 40 patients with suspected myocardial ischemia. Creatine kinase (CK), CK-MB, leukocyte count, C-reactive protein (CRP), lactate dehydrogenase (LDH), and glutamate-oxalacetate transaminase (GOT) were assessed at 0, 6, 12, 24, 48, and 72 hours after CABG as well as 12-lead standard electrocardiography (ECG).

RESULTS

Postoperative angiography of 40 patients with suspected myocardial infarction revealed graft failure or occluded native vessels in 13 (32.5%) individuals. Patients with graft or vessel occlusion presented elevated (P < .005) leukocyte counts (17,215 +/- 6632 vs 10,773 +/- 3902 G/L) immediately after CABG. CK-MB concentrations differed ( P < .05) at 6 hours after CABG (54 +/- 48 vs 30 +/- 18 U/L). CK, CRP, LDH, and GOT did not show any differences between both groups. Frequency of ECG ST-segment elevation was increased (P < .05) in ischemic patients (69.2% vs 29.6%).

CONCLUSIONS

Common signs of myocardial ischemia usually allow to diagnose unstable angina or myocardial infarction under native conditions. In contrast, these criteria frequently fail after CABG. Combined diagnostic criteria of elevated leukocytes (>14,000 G/L, at hour 0) and either ST elevation or CK-MB concentrations >35 U/L (at hour 6) at least seem to be very useful in detecting myocardial infarction after bypass grafting. In parallel, CK-MB elevation (>70 U/L, at hour 6) alone seems to predict ischemia. Both criteria should indicate angiography and potential revascularization. If these conditions were not fulfilled, the risk of perioperative myocardial infarction appears to be moderate.

Determination of Troponin I Release After CABG Surgery

BACKGROUND

Troponin I is used to diagnose myocardial infarction (MI). Its use and pattern of elevation is not well defined in coronary artery bypass graft (CABG) surgery. This study assessed the timing of troponin I elevation in patients undergoing urgent CABG.

METHOD

Patients undergoing urgent isolated-CABG with cardiopulmonary bypass were studied prospectively. Blood samples were taken to measure CK, CK-MB, and troponin I: preoperatively, 7 hours postoperatively, 14 to 18 hours postoperatively, 30 to 48 hours postoperatively, and on postoperative day 4. Electrocardiograms and in-hospital course were recorded. Perioperative MI (PMI) was defined by either (i) ECG criteria of new Q-waves in the presence of CK-MB elevation >50 microg/L or (ii) CK-MB > 100 microg/L.

RESULTS

Of the 50 patients studied, 6 met the criteria for PMI (12%); 2 by criteria (i) and 4 by criteria (ii). In patients not meeting the criteria for MI the troponin I level peaked at 7 hour post-op with a mean of 20.97 microg/L (95% CI, 17.11 to 24.83). At this time, patients who met the criteria for MI had a mean troponin I level of 46.85 microg/L (95% CI, 36.40 to 57.30). Of variables investigated for the 44 patients who did not meet MI criteria, only preoperative troponin I level impacted peak postoperative troponin I.

CONCLUSIONS

CABG elevates troponin I far beyond current diagnostic benchmarks without the clinical occurrence of a MI and appears to peak during the second postoperative day. An elevated preoperative troponin I may predict an elevated peak postoperative troponin I in patients who do not have a PMI.

Diagnosis of myocardial injury by biochemical markers: problems and promises

The role of biochemical markers in the diagnosis of acute coronary syndromes has increased considerably in the past decade. The World Health Organization previously defined acute myocardial infarction as a combination of at least 2 of 3 components: symptoms consistent with acute myocardial infarction, electrocardiogram changes diagnostic of acute myocardial infarction, and an enzyme pattern with classic rise and fall. Measurement of creatine kinase and its MB fraction by various assays was the gold standard for the diagnosis. Troponins are more specific and sensitive markers for myocardial injury, and their increasing utilization has resulted in a broadening of the definition of acute myocardial infarction to incorporate high-risk acute coronary syndromes. Previously, traditional enzyme evaluation left patients with small amounts of cellular death undiagnosed; these patients were categorized as having unstable angina or, worse, noncardiac chest pain. Newer markers now identify these patients as a subgroup at high risk for cardiac death or cardiac events. Newer therapeutic interventions and a more invasive strategy have been shown to improve outcomes in this high-risk subgroup. Increased specificity has also reduced the number of patients who undergo extensive, expensive, and invasive evaluations for noncardiac syndromes due to false elevations of traditional markers. This article comprehensively reviews the evolution of biochemical markers for the diagnosis of acute myocardial infarction, addressing their promise for improving delivery of care and outcomes and their technical and diagnostic pitfalls.

Revascularization during acute myocardial infarction: risks and benefits revisited

BACKGROUND

Indication for immediate revascularization during acute myocardial infarction (MI) is debated. Drug-resistant crescendo angina, as well as hemodynamic compromise, however, often requires acute operation. In this study the differential risks of acute coronary artery bypass grafting with and without MI were stratified.

METHODS

Five hundred eighteen patients undergoing isolated coronary artery bypass grafting were investigated. Thirty-nine patients underwent acute revascularization because of enzyme-proven or electrocardiogram-proven MI accompanied by crescendo angina, hemodynamic compromise, or both. They were compared with 33 emergent, 63 urgent, and 383 elective patients without MI. Preoperative risk factors for early mortality and necessity of continuous venovenous hemofiltration were analyzed by means of logistical regression analysis. Perioperative data were compared.

RESULTS

Early mortality of the MI cohort was 15.4%, in contrast to 15.2% in emergent, none in urgent, and 2.1% in elective patients. Left internal thoracic artery was used in 87% of MI, 97% of emergent, 94% of urgent, and 97% of elective patients. Intraaortic balloon pump was necessary in 50% of MI patients, 27% of emergent, 6.3% of urgent, and 3.1% of elective cases. Continuous venovenous hemofiltration was performed in 29% of MI patients, 15% of emergent, 4.9% of urgent, and 3.4% of elective patients. Hemodynamic instability significantly increased the odds ratio for early mortality and continuous venovenous hemofiltration.

CONCLUSIONS

Patients undergoing acute revascularization carried an elevated risk to die early notwithstanding the presence or absence of acute MI. Liberal use of left internal thoracic artery grafts was not detrimental in acute patients whereas liberal use of intraaortic balloon pump was beneficial. In almost 30% of MI patients, continuous venovenous hemofiltration was not necessary, implying a severely impaired perioperative hemodynamic condition. Immediate revascularization in the presence of acute MI is therefore indicated although it may be addressed as a separate high-risk group.

A comparison of cardiac troponin T and creatine kinase-MB for patient evaluation after cardiac surgery

OBJECTIVES

The aim of this study was to assess the role of serum markers of myocardial necrosis after cardiac surgery.

BACKGROUND

The role of serum troponin T (TnT) and creatine kinase-MB (CK-MB) for the risk stratification of patients after cardiac surgery remains undefined.

METHODS

Serum levels of TnT and CK-MB were measured from 224 patients every 8 h after cardiac surgery. The results of serum cardiac marker testing were correlated with adverse events, including new myocardial infarction (MI), cardiogenic shock or death. Univariable analysis identified factors predictive of complications, while stepwise logistic regression identified independent predictors of postoperative complications.

RESULTS

Cardiac marker elevation was universal after cardiac surgery. At all time points measured, compared with those patients without complications, the TnT levels from patients with complications were more significantly elevated (all: p < 0.0005). In contrast, among identically timed specimens, the levels of CK-MB from complicated patients were less reliably discriminatory. Multivariable analysis suggested that a TnT level in the highest quintile (> or = 1.58 ng/ml) was the strongest predictor of complications, including death (post-op, odds ratio [OR] = 31.0, 95% confidence interval [CI] = 3.67 to 263.1, p = 0.002) or shock (post-op: OR = 18.9, 95% CI = 2.29 to 156.1, p = 0.006; 18 h to 24 h: OR = 30.7, 95% CI = 3.75 to 250.7, p = 0.001), as well as the composite end points of death/MI (18 h to 24 h: OR = 60.1, 95% CI = 7.34 to 492.1, p < 0.0005), shock/MI (post-op: OR = 23.3, 95% CI = 2.82 to 191.4, p = 0.003; 18 h to 24 h: OR = 37.8, 95% CI = 4.66 to 307.3, p = 0.001) or death/shock/MI (post-op: OR = 20.0, 95% CI = 2.81 to 142.0, p = 0.003; 18 h to 24 h: OR = 67.4, 95% CI = 6.96 to 652.3, p < 0.0005). In contrast, in the presence of TnT, the results of CK-MB measurement added no independent prognostic information.

CONCLUSIONS

Troponin T is superior to CK-MB for the prediction of impending complications after cardiac surgical procedures.