Andrea Tkaczyk

Etiology of troponin elevation in critically ill patients.

PURPOSE The aim of this study was to assess the etiology of cardiac troponin elevation among patients admitted to the intensive care unit (ICU) and to examine whether etiology affects mortality and length of stay. METHODS All patients admitted over 2 months underwent screening with troponin measurements and were included if 1 or more measurements were elevated. Two adjudicators retrospectively reviewed patient charts to determine the likely cause of troponin elevation. RESULTS Of 103 patient admissions, 52 (50.5%) had 1 or more elevated troponin measurements, and 49 (94.2%) had medical charts available for review. Troponin elevation was adjudicated as myocardial infarction (MI) in 53.1% of patients, sepsis in 18.4%, renal failure in 12.2%, and other causes in 16.3%. Overall ICU mortality was 16.0%; 2.0% for patients with no troponin elevation, 23.1% in patients with MI, and 39.1% in patients with troponin elevation not due to MI. Having an elevated troponin level not due to MI was significantly associated with increased hospital mortality compared with having no troponin elevation. CONCLUSIONS The most common cause of troponin elevation among critically ill patients was MI. Patients with elevated troponin had worse outcomes compared with patients without troponin elevation, and troponin elevation not due to MI was predictive of increased hospital mortality.

Detecting myocardial infarction in critical illness using screening troponin measurements and ECG recordings

IntroductionTo use screening cardiac troponin (cTn) measurements and electrocardiograms (ECGs) to determine the incidence of elevated cTn and of myocardial infarction (MI) in patients admitted to the intensive care unit (ICU), and to assess whether these findings influence prognosis. This is a prospective screening study.Materials and methodsWe enrolled consecutive patients admitted to a general medical-surgical ICU over two months. All patients underwent systematic screening with cTn measurements and ECGs on ICU admission, then daily for the first week in ICU, alternate days for up to one month and weekly thereafter until ICU death or discharge, for a maximum of two months. Patients without these investigations ordered during routine clinical care underwent screening for study purposes but these results were unavailable to the ICU team. After the study, all ECGs were interpreted independently in duplicate for ischaemic changes meeting ESC/ACC criteria supporting a diagnosis of MI. Patients were classified as having MI (elevated cTn and ECG evidence supporting diagnosis of MI), elevated cTn only (no ECG evidence supporting diagnosis of MI), or no cTn elevation.ResultsOne hundred and three patients were admitted to the ICU on 112 occasions. Overall, 37 patients (35.9 per cent) had an MI, 15 patients (14.6 per cent) had an elevated cTn only and 51 patients (49.5 per cent) had no cTn elevation. Patients with MI had longer duration of mechanical ventilation (p < 0.0001), longer ICU stay (p = 0.001), higher ICU mortality (p < 0.0001) and higher hospital mortality (p < 0.0001) compared with those with no cTn elevation. Patients with elevated cTn had higher hospital mortality (p = 0.001) than patients without cTn elevation. Elevated cTn was associated with increased hospital mortality (odds ratio 27.3, 95 per cent CI 1.7 – 449.4), after adjusting for APACHE II score, MI and advanced life support. The ICU team diagnosed 18 patients (17.5 per cent) as having MI on clinical grounds; four of these patients did not have MI by adjudication. Thus, screening detected an additional 23 MIs not diagnosed in practice, reflecting 62.2 per cent of MIs ultimately diagnosed. Patients with MI diagnosed by the ICU team had similar outcomes to patients with MI detected by screening alone.ConclusionSystematic screening detected elevated cTn measurements and MI in more patients than were found in routine practice. Elevated cTn was an independent predictor of hospital mortality. Further research is needed to evaluate whether screening and subsequent treatment of these patients reduces mortality.

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 ische-mic 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.

The diagnosis of myocardial infarction in critically ill patients: An agreement study

PURPOSE The aim of the study was to assess agreement among 4 intensivists in diagnosing myocardial infarction (MI) in critically ill patients based on screening electrocardiograms (ECGs) and cardiac troponin (cTn) levels. METHODS Consecutive patients admitted to a medical-surgical intensive care unit (ICU) underwent systematic screening with 12-lead ECGs and cTn measurements throughout their ICU stay. Independently, 4 raters interpreted the ECGs assessing for changes indicative of ischemia and then classified each patient as to whether they met diagnostic criteria for MI based on the screening cTn measurements and ECG results. A priori, 2 raters were designated the primary adjudicators, and their consensus was used as the reference for the agreement statistics. Agreement on MI diagnosis was calculated for the 4 raters and expressed as raw agreement, kappa (chance-corrected agreement) and varphi (chance-independent agreement, calculated using pairs). RESULTS Among 103 enrolled patients, 37 (35.9%) had MI according to the primary adjudicators. The raw agreement for diagnosing MI was 79% (substantial), kappa was 0.24 (fair), and varphi ranged from 0.12 to 0.73 (slight to substantial). CONCLUSIONS Diagnosing MI in the ICU remains a challenge due to variable agreement in 12-lead ECG interpretation. Such variation in practice may contribute to underrecognition of MI during critical illness.

Thromboprophylaxis for hospitalized medical patients: a multicenter qualitative study.

BACKGROUND Observational studies have documented that medical patients infrequently receive venous thromboembolism (VTE) prevention. OBJECTIVE To understand the barriers to, and facilitators of, optimal thromboprophylaxis. PATIENTS Hospitalized medical patients. DESIGN We conducted in-depth interviews with 15 nurses, 6 pharmacists, 12 physicians with both clinical and managerial experience, and 3 hospital administrators. SETTING One university-affiliated and 2 community hospitals. INTERVENTION Interviews were audiotaped and transcribed verbatim. Transcripts were reviewed and interpreted independently in duplicate. MEASUREMENT Analysis was conducted using grounded theory. RESULTS Physicians and pharmacists affirmed that evidence supporting heparin is strong and understood. Clinicians, particularly nurses, reported that mobilization was important, but were uncertain about how much mobilization was enough. Participants believed that depending on individual physicians for VTE prevention is insufficient. The central finding was that multidisciplinary care was also perceived as a barrier to effective VTE prevention because it can lead to unclear accountability by role confusion. Participants believed that a comprehensive, systems approach was necessary. Suggestions included screening and risk-stratifying all patients, preprinted orders at hospital admission that are regularly reevaluated, and audit and feedback programs. Patient or family-mediated reminders, and administrative interventions, such as hiring more physiotherapists and profiling thromboprophylaxis in hospital accreditation, were also endorsed. CONCLUSIONS Universal consideration of thromboprophylaxis finds common ground in multidisciplinary care. However, results of this qualitative study challenge the conviction that either individual physician efforts or multidisciplinary care are sufficient for optimal prevention. To ensure exemplary medical thromboprophylaxis, clinicians regarded coordinated, systemwide processes, aimed at patients, providers, and administrators as essential.