Troponin I and myocardial injury in the ICU

Myocardial Injury on Admission as a Risk in Critically Ill COVID-19 Patients: A Retrospective in-ICU Study

OBJECTIVE

The aim of this study was to investigate the incidence, clinical presentation, cardiovascular (CV) complications, and mortality risk of myocardial injury on admission in critically ill intensive care unit (ICU) inpatients with COVID-19.

DESIGN

A single-center, retrospective, observational study.

SETTING

A newly built ICU in Tongji hospital (Sino-French new city campus), Huazhong University of Science and Technology, Wuhan, China.

PARTICIPANTS

Seventy-seven critical COVID-19 patients.

INTERVENTIONS

Patients were divided into a myocardial injury group and nonmyocardial injury group according to the on-admission levels of high-sensitivity cardiac troponin I.

MEASUREMENTS AND MAIN RESULTS

Demographic data, clinical characteristics, laboratory tests, treatment, and clinical outcome were evaluated, stratified by the presence of myocardial injury on admission. Compared with nonmyocardial injury patients, patients with myocardial injury were older (68.4 ± 10.1 v 62.1 ± 13.5 years; p = 0.02), had higher prevalence of underlying CV disease (34.1% v 11.1%; p = 0.02), and in-ICU CV complications (41.5% v 13.9%; p = 0.008), higher Acute Physiology and Chronic Health Evaluation II scores (20.3 ± 7.3 v 14.4 ± 7.4; p = 0.001), and Sequential Organ Failure Assessment scores (7, interquartile range (IQR) 5-10 v 5, IQR 3-6; p < 0.001). Myocardial injury on admission increased the risk of 28-day mortality (hazard ratio [HR], 2.200; 95% confidence interval [CI] 1.29 to 3.74; p = 0.004). Age ≥75 years was another risk factor for mortality (HR, 2.882; 95% CI 1.51-5.50; p = 0.002).

CONCLUSION

Critically ill patients with COVID-19 had a high risk of CV complications. Myocardial injury on admission may be a common comorbidity and is associated with severity and a high risk of mortality in this population.

Prognostic Value of Cardiac Troponin I and T on Admission in Mortality of Multiple Trauma Patients Admitted to the Emergency Department: a Prospective Follow-up Study

Introduction:

The relationship between increased levels of cardiac troponins and morbidity and mortality of traumatic patients is not still well recognized.

Aim:

The aim of this study was to investigate the prognostic value of cardiac troponin I and T on admission in mortality of multiple trauma patients admitted to the emergency department.

Methods:

In this prospective follow-up study, the cardiac troponin I and T levels were measured in patients with multiple trauma referring to the emergency department (ED) between March 2014 and February 2015 at Imam Khomeini Hospital, Sari, Iran. Patients were followed prospectively until discharge from hospital or death.

Results:

The levels of cardiac troponins I and T in patients with multiple trauma were significantly associated with their mortality, especially at the level of 0.5 and 1.2 μg/dl (p<0.05). Multivariate regression analysis showed association of level of cardiac troponin I and T with patients’ mortality, after controlling for patients’ age, vital signs and GCS on admission. The sensitivity and specificity of troponin I at levels greater than 0.4 μg/dl in predict mortality in this study were as 65.5% and 55.3%, while the values for troponin T were 65.1% and 54.9%, respectively.

Conclusion:

Elevated cardiac troponin I and T levels provide excellent prognostic information regarding mortality in patients with multiple-trauma, independent of age, hemodynamic variables and GCS score.

Myocardial infarction in intensive care units: A systematic review of diagnosis and treatment

INTRODUCTION

Patients in the intensive care unit are vulnerable to myocardial injury from a variety of causes, both ischaemic and non-ischaemic. It is challenging for ICU clinicians to apply the conventional guidance concerning diagnosis and treatment. We conducted this review to examine the evidence concerning diagnosis and treatment of myocardial infarction in the ICU.

METHODS

A systematic review was performed to identify relevant studies.

RESULTS

19 studies concerning use of ECG, cardiac enzymes, echocardiography and angiography were identified. 4 studies considered treatment of myocardial infarction.

CONCLUSIONS

Regular 12 lead ECG or 12 lead ECG monitoring is more sensitive than 2 lead monitoring, regular measurement of cardiac enzymes is more sensitive than when provoked by symptoms. Coronary angiography rarely identifies treatable lesions, without regional wall motion abnormality on echocardiography. Evidence relating to treatment was limited. A potential strategy to diagnose myocardial infarctions in the ICU is proposed.

Use of Admission Troponin in Critically Ill Medical Patients

Serum troponin I (TnI) is a sensitive marker of cardiac injury. A relation between elevated TnI and mortality has been suggested. In this retrospective chart review of 221 patients admitted to the medical intensive care unit (MICU) during a 6-month period, the authors studied the use of admission TnI levels in predicting mortality in MICU-admitted patients. Data retrieved included demographics, admission diagnosis, troponin, electrocardiogram, Acute Physiology and Chronic Health Evaluation (APACHE) II score, echocardiogram, requirements for mechanical ventilation and vasopressor support, development of multiorgan failure, mortality, and discharge disposition. There were 132 patients for whom TnI level was sent within 24 hours of admission; these patients comprised the study group. The median age was 70 years; 59% were female. The mean APACHE II score was 22. Troponin I was positive in 31% of patients (median level, 0.4 Ug/L; range 0-358 Ug/L). The hospital mortality was 39%. Positive TnI showed a weak association with intensive care unit (ICU) mortality ( P= .049) but not with overall mortality. There was no significant correlation between admission TnI concentration and APACHE II score ( P= .33), administration of vasopressor medications ( P= .115), or development of multiorgan failure ( P= .64). The authors concluded that there is no benefit in obtaining a routine admission troponin level in MICU patients when an acute coronary event is not suspected.

Cardiac Troponins in Dogs and Cats

Cardiac troponins are sensitive and specific markers of myocardial injury. The troponin concentration can be thought of as a quantitative measure of the degree of injury sustained by the heart, however, it provides no information on the cause of injury or the mechanism of troponin release. Conventionally, the cardiac troponins have been used for diagnosis of acute myocardial infarction in humans and have become the gold standard biomarkers for this indication. They have become increasingly recognized as an objective measure of cardiomyocyte status in both cardiac and noncardiac disease, supplying additional information to that provided by echocardiography and ECG. Injury to cardiomyocytes can occur through a variety of mechanisms with subsequent release of troponins. Independent of the underlying disease or the mechanism of troponin release, the presence of myocardial injury is associated with an increased risk of death. As increasingly sensitive assays are introduced, the frequent occurrence of myocardial injury is becoming apparent, and our understanding of its causes and importance is constantly evolving. Presently troponins are valuable for detecting a subgroup of patients with higher risk of death. Future research is needed to clarify whether troponins can serve as monitoring tools guiding treatment, whether administering more aggressive treatment to patients with evidence of myocardial injury is beneficial, and whether normalizing of troponin concentrations in patients presenting with evidence of myocardial injury is associated with reduced risk of death.

Prediction of long-term outcome by measurement of serum concentration of cardiac troponins in critically ill dogs with systemic inflammation

BACKGROUND

Myocardial injury, detected by cardiac troponin I and T (cTnI and cTnT), has been associated with long-term death in the noncardiac human intensive care unit (ICU).

HYPOTHESIS

Presence of myocardial injury predicts 1-year case fatality in critically ill dogs with systemic inflammation.

ANIMALS

Thirty-eight dogs with evidence of systemic inflammation and no primary cardiac disease.

METHODS

Prospective cohort study. In dogs admitted to the ICU with evidence of systemic inflammation, blood samples were obtained at ICU admission for measurement of cTnI and cTnT, and cTnI was measured once daily during ICU hospitalization. Receiver operating characteristic (ROC) curves were used to examine prognostic capacity of admission cTnI, admission cTnT, and peak cTnI concentrations.

RESULTS

One-year case fatality rate was 47% (18/38 dogs). Admission cTnI concentrations were (median [range]) 0.48 [0.004-141.50] ng/mL, and peak cTnI concentrations were 1.21 [0.021-141.50] ng/mL. Admission cTnT concentrations were 15 [<13-3744] ng/L. For each marker, non-survivors had significantly higher concentrations than survivors (P = .0082-.038). ROC analyses revealed areas under curves [95% CI] of 0.707 [0.537-0.843] for peak cTnI and 0.739 [0.571-0.867] for admission cTnT, respectively. At the optimal cut-off, concentrations were 1.17 ng/mL (peak cTnI) and 23 ng/L (admission cTnT), sensitivities were 72% and 72%, and specificities were 70% and 80%, respectively.

CONCLUSIONS AND CLINICAL IMPORTANCE

While peak cTnI and admission cTnT are significantly related to 1-year case fatality in critically ill dogs with systemic inflammation, low sensitivities and specificities prevent their prediction of long-term outcome in individual patients. Troponins might play a role in identification of dogs at long-term risk of death.

Prognostic importance of myocardial injury in critically ill dogs with systemic inflammation

BACKGROUND

In noncardiac critical disease in humans, myocardial injury as detected by cardiac troponin I and T (cTnI and cTnT) has been linked to high intensive care unit (ICU) death independent of prognostic composite scoring.

HYPOTHESIS

Presence of myocardial injury predicts short-term death in critically ill dogs with systemic inflammation and provides additional prognostic information when combined with established canine prognostic composite scores.

ANIMALS

Forty-two dogs admitted to the ICU with evidence of systemic inflammation and no primary cardiac disease.

METHODS

Prospective cohort study. Blood samples were obtained at ICU admission for the measurement of cTnI and cTnT, C-reactive protein, and several cytokines. The acute patient physiologic and laboratory evaluation (APPLE) score and the survival prediction index were calculated within the first 24 hours of admission. Receiver operating characteristic (ROC) curves were used to examine the prognostic capacity of each biomarker and severity score. Multiple logistic regression analysis was performed to evaluate whether cardiac markers significantly contributed to severity scores.

RESULTS

Twenty-eight day case fatality rate was 26% (11/42 dogs). cTnI concentrations were (median [range]) 0.416 [0.004-141.5] ng/mL and cTnT concentrations were 13.5 [<13-3,744] ng/L. cTnI, cTnT, and the APPLE score were all significant prognosticators with areas under the ROC curves [95% CI] of 0.801 [0.649; 0.907], 0.790 [0.637; 0.900], and 0.776 [0.621; 0.889], respectively. cTnI significantly contributed to the APPLE score in providing additional prognostic specificity (P = .025).

CONCLUSIONS AND CLINICAL IMPORTANCE

Markers of myocardial injury predict short-term death in dogs with systemic inflammation and cTnI significantly contributes to the APPLE score.

Increased blood troponin levels in ICU patients

PURPOSE OF REVIEW

Cardiac troponins in serum have become the biomarkers of choice for the diagnosis of myocardial infarction. Yet, troponin can also be elevated by a multitude of causes in the absence of overt myocardial ischemia. Such nonspecific elevations are particularly common in the critically ill. This article aims to provide information on the significance of troponin elevations in unselected critically ill patients and in patients with sepsis or septic shock.

RECENT FINDINGS

Recent studies reconsider the possible association of troponin elevations with myocardial infarction in unselected critically ill patients. There are also more data on the prognostic significance of troponin in this population. In patients with sepsis, recent studies suggest that troponin may be a reliable index of sepsis-induced myocardial dysfunction, although the implications of this finding in the management of sepsis remain unclear for the time being. Troponin also appears to be a predictor of short and possibly also long-term outcome in septic patients. The advent of newer assays with even higher sensitivity, may lead to further redefinition of the role of troponin in the ICU.

SUMMARY

Troponin is frequently elevated in critically ill patients. More research is needed on the diagnostic and prognostic significance and possible clinical applications of troponin measurements in patients with sepsis and critical illness.

Cardiac biomarkers in the critically ill

Cardiac biomarkers have well-established roles in acute coronary syndrome and congestive heart failure. In many instances, the detection of cardiac biomarkers may aid in the diagnosis and risk assessment of critically ill patients. Despite increasing interest in the use of cardiac biomarkers in noncardiac critical illness, no clear consensus exists on how and in which settings markers should be measured. This article briefly describes what constitutes an ideal biomarker and focuses on those that have been most well studied in critical illness, specifically troponin, the natriuretic peptides, and heart-type fatty acid-binding protein.

Bench-to-bedside review: the value of cardiac biomarkers in the intensive care patient

The use of cardiac biomarkers in the intensive care setting is gaining increasing popularity. There are several reasons for this increase: there is now the facility for point-of-care biomarker measurement providing a rapid diagnosis; biomarkers can be used as prognostic tools; biomarkers can be used to guide therapy; and, compared with other methods such as echocardiography, the assays are easier and much more affordable. Two important characteristics of the ideal biomarker are disease specificity and a linear relationship between the serum concentration and disease severity. These characteristics are not present, however, in the majority of biomarkers for cardiac dysfunction currently available. Those clinically useful cardiac biomarkers, which naturally received the most attention, such as troponins and B-type natriuretic peptide, are not as specific as was originally thought. In the intensive care setting, it is important for the user to understand the degree of specificity of these biomarkers and that the interpretation of the results should always be guided by other clinical information. The present review summarizes the available biomarkers for different cardiac conditions. Potential biomarkers under evaluation are also briefly discussed.

Troponin I in the intensive care unit setting: from the heart to the heart

When measured in the plasma, cardiac troponins T (cTnT) and I (cTnI) are considered to be highly specific markers of myocardial cell damage; however, research has demonstrated that troponin elevation may associated with causes other than coronary artery disease. In the intensive care unit (ICU) setting, increased cTnI levels are quite common findings and when documented, even on admission, intensivists should bear in mind that this laboratory finding holds a prognostic role independent of the reason for ICU admission. The mechanism(s) (such as demand ischemia, myocardial strain, etc.) and not simply the cause (i.e., renal failure) of the increment in serum cTnI should be investigated to better tailor the therapeutical regimen in the single patient. In this review, we therefore consider the nonthrombotic causes of troponin elevation in the critical setting.

Use and Misuse of Cardiac Troponins in Clinical Practice

Cardiac troponins are very sensitive and specific markers of myocardial injury. Elevated troponin levels in the setting of acute coronary syndrome are diagnostic of acute myocardial infarction and provide guidance to clinicians with regard to appropriate use of intensive medical and revascularization therapies. However, elevated troponin levels are commonly seen in several noncoronary ischemia presentations and create considerable confusion among clinicians in these settings. In this review article, we discuss the utility of troponins in various clinical settings and present a "common sense" approach to interpreting troponin elevation outside the setting of acute coronary syndrome.

Reliability of electrocardiogram interpretation in critically ill patients

OBJECTIVE

To assess the intrarater and interrater reliability of electrocardiogram (ECG) interpretation in critically ill patients and to assess the effect of knowledge of cardiac troponin values on these reliability estimates.

DESIGN

Prospective cohort study.

SETTING

Fifteen-bed medical-surgical intensive care unit.

PATIENTS

Consecutive adults admitted over a 2-month period.

MEASUREMENTS AND RESULTS

All consecutive 12-lead ECGs were interpreted independently by two raters for the presence of myocardial ischemia or infarction and secondarily for specific ischemic ECG abnormalities. The ECGs were first interpreted blinded to the patient's troponin levels and reinterpreted on two separate occasions, blinded and unblinded to the troponin values. Results are reported using chance-independent agreement (phi) with associated 95% confidence intervals. For the presence of ischemia or infarction, the intrarater reliability ranged from fair to moderate (phi = 0.35 [95% confidence interval = 0.16, 0.52] and 0.59 [0.33, 0.77] for the two raters, respectively); interrater reliability was slight when blinded to troponin levels (phi = 0.18 [0.03, 0.32]) and increased to moderate when the raters were unblinded to troponin values (phi = 0.52 [0.33, 0.66], p value for the difference = .004). For specific ECG changes, the intrarater and interrater reliability were low for T-wave flattening, whereas detection of a left bundle branch block showed high reliability.

CONCLUSIONS

ECG interpretation in critically ill patients for the presence of myocardial ischemia or infarction showed moderate reliability at best; however, there was high reliability for specific ECG changes. Knowledge of the patient's troponin values increased the reliability for all studied ECG changes and resulted in a statistically significant increase in the interrater reliability for diagnosing myocardial ischemia or infarction. Additional studies assessing the appropriate methods of diagnosing myocardial ischemia and infarction and assessing the reliability of these diagnostic tests in critically ill patients are required.

Elevated Cardiac Troponin Levels in Critically Ill Patients: Prevalence, Incidence, and Outcomes

• Background Levels of cardiac troponin, a sensitive and specific marker of myocardial injury, are often elevated in critically ill patients.

• Objectives To document elevated levels of cardiac troponin I in patients in a medical-surgical intensive care unit and the relationship between elevated levels and electrocardiographic findings and mortality.

• Methods A total of 198 patients expected to remain in the intensive care unit for at least 72 hours were classified as having myocardial infarction (cardiac troponin I level ≥1.2 μg/L and ischemic electrocardiographic changes), elevated troponin level only (≥1.2 μg/L and no ischemic electrocardiographic changes), or normal troponin levels. Events were classified as prevalent if they occurred within 48 hours after admission and as incident if they occurred 48 hours or later after admission. Factors associated with mortality were examined by using regression analysis.

• Results A total of 171 patients had at least one troponin level measured in the first 48 hours. The prevalence of elevated troponin level was 42.1% (72 patients); 38 patients (22.2%) had myocardial infarction, and 34 (19.9%) had elevated troponin level only. After the first 48 hours, 136 patients had at least 1 troponin measurement. The incidence of elevated troponin level was 11.8% (16 patients); 7 patients (5.1%) met criteria for myocardial infarction, and 2 (1.5%) had elevated troponin level only. Elevated levels of troponin I at any time during admission were associated with mortality in the univariate but not the multivariate analysis.

• Conclusions Elevated levels of cardiac troponin I in critically ill patients do not always indicate myocardial infarction or an adverse prognosis.

Myocardial injury in critically ill patients: relation to increased cardiac troponin I and hospital mortality

OBJECTIVE

To examine the relationship between myocardial injury, assessed by cardiac troponin I (cTnI) levels, and outcome in selected critically ill patients without acute coronary syndromes or cardiac dysfunction.

DESIGN AND SETTING

Prospective, observational study in the emergency ICU of a university teaching hospital.

POPULATION

Over a 6-month period, 217 consecutive patients admitted to the ICU were studied.

METHODS AND RESULTS

cTnI assays were performed in all patients on admission to the ICU. The incidence of myocardial injury, defined by cTnI level > 0.1 ng/mL, was 32% (69 of 217 patients). Overall mortality was 27% (58 of 217 patients). Patients with myocardial injury had a mortality rate of 51%, compared with only 16% mortality for those without myocardial injury (p < 0.001). The hospital mortality rate was highest among older patients (71 +/- 14% vs 58.5 +/- 20%, p < 0.0001) and patients with higher simplified acute physiology scale (SAPS) II score (62 +/- 25% vs 37 +/- 17%, p < 0.0001). Mechanical ventilation was associated with higher in-hospital death (50% vs 31%, for patients who died in the hospital vs those who were discharged alive; p = 0.03). Elevated blood levels of cTnI were found to be independently associated with hospital mortality, regardless of the presence of SAPS II score and mechanical ventilation, in the logistic regression analysis (odds ratio, 2.09; 95% confidence interval, 1.06 to 4.11; p = 0.01).

CONCLUSIONS

This study demonstrates the high frequency of myocardial injury (32%) in critically ill patients without acute coronary syndromes or cardiac dysfunction on admission to ICU. Myocardial injury is an independent determinant of hospital mortality. Assessment of myocardial injury on admission to ICU would make it possible to identify patients at increased risk of death.

Elevated troponin and myocardial infarction in the intensive care unit: a prospective study

INTRODUCTION

Elevated troponin levels indicate myocardial injury but may occur in critically ill patients without evidence of myocardial ischemia. An elevated troponin alone cannot establish a diagnosis of myocardial infarction (MI), yet the optimal methods for diagnosing MI in the intensive care unit (ICU) are not established. The study objective was to estimate the frequency of MI using troponin T measurements, 12-lead electrocardiograms (ECGs) and echocardiography, and to examine the association of elevated troponin and MI with ICU and hospital mortality and length of stay.

METHOD

In this 2-month single centre prospective cohort study, all consecutive patients admitted to our medical-surgical ICU were classified in duplicate by two investigators as having MI or no MI based on troponin, ECGs and echocardiograms obtained during the ICU stay. The diagnosis of MI was based on an adaptation of the joint European Society of Cardiology/American College of Cardiology definition: a typical rise or fall of an elevated troponin measurement, in addition to ischemic symptoms, ischemic ECG changes, a coronary artery intervention, or a new cardiac wall motion abnormality.

RESULTS

We screened 117 ICU admissions and enrolled 115 predominantly medical patients. Of these, 93 (80.9%) had at least one ECG and one troponin; 44 of these 93 (47.3%) had at least one elevated troponin and 24 (25.8%) had an MI. Patients with MI had significantly higher mortality in the ICU (37.5% versus 17.6%; P = 0.050) and hospital (50.0% versus 22.0%; P = 0.010) than those without MI. After adjusting for Acute Physiology and Chronic Health Evaluation II score and need for inotropes or vasopressors, MI was an independent predictor of hospital mortality (odds ratio 3.22, 95% confidence interval 1.04-9.96). The presence of an elevated troponin (among those patients in whom troponin was measured) was not independently predictive of ICU or hospital mortality.

CONCLUSION

In this study, 47% of critically ill patients had an elevated troponin but only 26% of these met criteria for MI. An elevated troponin without ischemic ECG changes was not associated with adverse outcomes; however, MI in the ICU setting was an independent predictor of hospital mortality.

Cardiac troponins in intensive care

The cardiac troponins are integral components of the myofibrillary apparatus and they regulate muscle contraction. The measurement of cardiac troponins has replaced other biomarkers for the specific detection of myocardial necrosis and for the diagnosis of myocardial infarction. The tissue specificity plus sensitivity of the measurement technology has meant that cardiac damage can be detected in circumstances other than conventional acute coronary syndromes. The ability to specifically detect cardiac damage as part of multiple organ failure in intensive care patients has been shown to provide prognostic information, but it is unclear whether this is a dependent or an independent marker of outcome.

Myocardial ischemia, cardiac troponin, and long-term survival of high-cardiac risk critically ill intensive care unit patients*

OBJECTIVES

To determine the incidence and association of myocardial ischemia with troponin elevation and survival in high-cardiac-risk intensive care patients.

DESIGN

Prospective observational study.

SETTING

Intensive care unit of a tertiary hospital.

SUBJECTS

One-hundred one general intensive care unit patients having a history of coronary artery disease or at least two risk factors for coronary artery disease.

INTERVENTIONS

Continuous 12-lead electrocardiographic monitoring with on-line ST-trend analysis, daily cardiac troponin measurements, clinical and physiologic assessment, and up to 2-yr follow-up for survival.

MEASUREMENTS AND MAIN RESULTS

During 8,988 hrs or a mean +/- sd of 95 +/- 85 hrs/patient of continuous 12-lead electrocardiographic monitoring, 21 patients (21%) had ischemic ST-segment changes, characterized in most (19) by ST depression and lasting >60 mins in 15 (71.4%). Of the 38 patients (38%) with troponin elevation, myocardial infarction was clinically suspected in four and myocardial ischemia on continuous 12-lead electrocardiographic monitoring was observed in 14 (36.8%). Fourteen (66.7%) of the patients with ischemic ST changes and 12 (75%) of those with prolonged (>60 mins) ischemia had troponin elevation. The sensitivity, specificity, and positive and negative predictive values of prolonged (>60 mins) ischemia predicting troponin elevation were 31.6%, 95.2%, 80.0%, and 69.8%, respectively. Prolonged (>60 mins) ischemia was significantly associated with troponin elevation by both univariate and multivariate analyses (odds ratio = 9.0; p = .008). Acute Physiology and Chronic Health Evaluation II score, renal failure, and the use of norepinephrine also independently predicted troponin elevation. Troponin but not ischemia predicted increased 1-month, 6-month, and 2-yr mortality (odds ratio = 6.0, 3.2, and 2.99, respectively; p < .001).

CONCLUSIONS

Silent ischemia is strongly associated with troponin elevation in high-cardiac-risk intensive care unit patients, and troponin elevation predicts both early and late mortality.

CARDIAC TROPONIN I LEVELS ARE A RISK FACTOR FOR MORTALITY AND MULTIPLE ORGAN FAILURE IN NONCARDIAC CRITICALLY ILL PATIENTS AND HAVE AN ADDITIVE EFFECT TO THE APACHE II SCORE IN OUTCOME PREDICTION

Cardiac troponin I (cTnI) is a specific marker of myocardial damage used in the diagnosis of acute coronary syndrome (ACS). Recent studies have shown that cTnI levels can also be elevated in patients without ACS, such as in sepsis and trauma patients, and that this is associated with an adverse prognosis. We have evaluated the clinical implications and prognostic significance of serum cTnI levels in noncardiac critically ill patients in a prospective observational study in a general medical intensive care unit at a tertiary-level hospital. A total of 108 consecutive patients without ACS or other cardiac disease was enrolled. Serum cTnI levels were measured on admission using enzyme-linked immunoabsorbant assay kits. Clinical laboratory parameters and outcome were compared between patients with elevated and normal cTnI levels. The prognostic significance of cTnI levels and the Acute Physiology And Chronic Health Evaluation (APACHE) II score was also analyzed. Forty-nine patients (45%) had elevated cTnI levels and 59 (55%) had normal levels. Compared with patients with normal cTnI levels, patients with elevated levels had a higher incidence of new failure of two or more organs, had a lower left ventricular ejection fraction during admission, were more likely to be associated with bacteremia, and had a higher intensive care unit mortality; they also had a significantly shorter survival over a 180-day follow up, before and after stratification by the APACHE II score. Multiple organ failure was the leading cause of mortality in patients with elevated cTnI levels. By multivariate analysis, elevated cTnI levels, a high APACHE II score, and underlying cancer were the three most important independent predictors for a shorter survival. Combination analysis showed a shorter survival in patients with a high APACHE II score plus elevated cTnI levels than in patients with a high APACHE II score or elevated cTnI levels alone. In conclusion, elevated serum cTnI levels is a risk factor for multiple organ failure and mortality in noncardiac critically ill patients, and the cTnI levels and APACHE II score have an additive effect in outcome prediction.

Cardiac troponin I: a reliable marker and early myocardial involvement with meningoencephalitis after fatal enterovirus-71 infection

OBJECTIVES

A major outbreak of enterovirus 71 (EV71) in Taiwan in 1998 caused many severe cases and 78 deaths. Our purpose was to find reliable markers and early indicators of fatal EV71 central nervous system (CNS) infection.

METHODS

From June 2000 to November 2001, 21 patients with hand foot mouth disease or herpangina with CNS infection were admitted to Kaohsiung Veterans General Hospital. All 21 had culture-confirmed EV71 infection or were EV71 IgM positive. Patients were divided into two groups: group I included the five fatalities at our institution and group II, the 16 surviving patients.

RESULTS

Of the 21 infants and children with EV71 infection with CNS involvement, MR imaging studies were completed on 17, and 15 showed hyperintensity in the posterior portions of brain stem. All patients received intravenous immunoglobulin (IVIG) 1 g/day for two days and supportive care. Five patients rapidly deteriorated owing to irreversible hypotension and died. The other 16 patients recovered completely without sequel. In group I patients, the decrease of cardiac ejection function is significant and laboratory findings showed lower platelet count (P=0.0192). The mean of initial cTnI level for groups I and II was 10.6+/-11.6 and 0.48+/-0.55 ng/dl, respectively, higher in group I than in II (P=0.0019).

CONCLUSION

We hypothesized that like patients with severe burns, those with severe EV-71 CNS meningoencephalitis have varying degrees of non-ischemic cardiac injury, manifesting as leakage of cTnI from myocytes into the circulation. EV-71 CNS meningoencephalitis likely to die with an early myocardial involvement evidenced by reduced ejection fraction and release of cTnI. We conclude that fatal EV71 CNS infection quickly leads to death due to severe encephalopathy associated with cardiomyopathy.

Test strategies for the detection of myocardial damage

In the space of half a century, cardiac marker testing has advanced incrementally from enzymes present in nearly all tissues to proteins having remarkable specificity for myocardium. Markers with other desirable properties, such as earlier release, have also been introduced and others may be anticipated, although a single perfect marker is not on the horizon. Optimum application of these new markers still requires improved robustness and harmonization of commercial assays, and continuing insights in the pathophysiology of acute coronary syndromes. As these advances occur, future testing will likely focus more on therapeutic decisions than on arbitrary diagnostic classifications.

Glucose, insulin and potassium for heart protection during cardiac surgery

BACKGROUND

Coronary artery bypass grafting with hypothermic cardiac arrest and cardiopulmonary bypass (CPB) is associated with myocardial injury. Our study investigated whether an infusion of glucose, insulin and potassium (GIK) during elective coronary artery bypass surgery decreases myocardial cell death.

METHODS

We measured cardiac troponin I (cTnI), a myofibrillar structural protein, which is a sensitive and specific indicator of myocytic injury. With ethics committee approval, 42 patients were enrolled into a randomized, prospective, double-blinded study. In the GIK group, 500 ml of 50% dextrose solution containing 100 IU insulin and potassium 80 mmol was infused at the rate of 0.75 ml kg(-1) h(-1). Patients in the non-GIK group received 5% dextrose solution at the same rate. Arterial blood samples were taken before induction of anaesthesia, after removal of the aortic clamp and 6 and 12 h after CPB.

RESULTS

In both groups there was an increase in cTnI concentration (P<0.05), which was greatest about 6 h after CPB. At no time did the cTnI concentration differ between the two groups.

CONCLUSION

The results suggest that GIK does not decrease the irreversible myocardial damage associated with routine coronary artery bypass surgery.