Sensitivity of routine intensive care unit surveillance for detecting myocardial ischemia*

[Diagnosis and Management of Perioperative Myocardial Ischemia after Elective Aortic Aneurysm Surgery]

INTRODUCTION

Perioperative myocardial ischemia (PMI) is a serious postoperative complication. Aortic operations represent an especially high-risk surgery concerning cardiac complications. This aim of this study was to analyse the clinical features of PMI after elective aortic aneurysm surgery.

PATIENTS AND METHODS

This study is a retrospective analysis of 863 patients who underwent elective aortic aneurysm surgery between 2005 and 2012 in the Department of Vascular and Endovascular Surgery of Heidelberg University Hospital with regard to PMI. The PMI diagnosis was based on a positive serum troponin diagnostic test. We evaluated the clinical course, time point of the diagnosis and features of diagnostics to characterise PMI. Moreover, we analysed the treatment options and management of the patients' discharge.

RESULTS

Thirty-one patients (3.6% of 863) with PMI after elective aortic aneurysm surgery were identified. Of these, 21 patients (67.7%) underwent open surgery and 10 patients (32.3%) received endovascular treatment. PMI was diagnosed in 24 patients (77%) during the first 3 days. More than half of these patients (16/31) were clinically asymptomatic. Electrocardiogram did not show pathological findings in 24 cases (77.4%). The first troponin measurement was not elevated in eight patients (25.8%). Drug therapy alone was used in 17 cases (54.8%) of PMI, coronary catheterisation was performed in 12 patients (38.7%) and two patients (6.5%) received aortocoronary bypass. Fourteen patients (45.1%) were discharged home and another 14 patients (44.1%) were transferred to another hospital or to a rehabilitation institution. Two patients died because of multi-organ failure.

CONCLUSION

PMI is not a rare complication after elective aortic surgery. The diagnosis of PMI can be challenging because of occult symptoms especially in a perioperative setting. Due to the potentially serious consequences, cardiac enzyme diagnostics should be initiated immediately if there is suspicion of PMI or routinely in defined at-risk patients after aortic surgery.

[Diagnosis of myocardial infarction in critically ill, ventilated patients]

Elevated cardiac troponin values are frequently observed in critically ill patients. These are often not due to myocardial infarction (MI) but caused by various other etiologies of myocardial injury. Understanding the etiology of any troponin elevation is of enormous importance for management and therapy. According to the fourth version of the Universal Definition of MI, myocardial injury is present if at least one troponin value is above the 99th percentile upper reference limit and considered acute, when a rise and/or fall occurs. Patients with acute MI are a subgroup of patients with acute myocardial injury, who present in an ischemic clinical context. Variables defining the clinical criteria of MI include symptoms of ischemia, presumably new electrocardiographic (ECG) changes or imaging evidence of new loss of viable myocardium or regional wall motion abnormalities, or detection of an intracoronary thrombus. In critically ill or mechanically ventilated patients, the diagnosis of MI is challenging due to limitations in history taking, co-existence of comorbidities, overlapping symptoms and equivocal or unspecific ECG changes. This article presents the diagnostic criteria of the Universal MI definition, discusses subtypes of MI and focuses on various differential diagnoses. Furthermore, implications of diagnosis of MI in critically ill patients, especially regarding the use of ECG and troponin assays, are discussed.

Cardiac arrest due to an unexpected acute myocardial infarction during head and neck surgery: A case report

Major cardiac complication such as acute myocardial infarction can occur unexpectedly in patients without risk factors. We experienced cardiac arrest due to an unexpected acute myocardial infarction in a patient without any risk factors during head and neck reconstructive surgery. The patient was diagnosed with acute myocardial infarction after return of spontaneous circulation. With immediate percutaneous coronary intervention, the patient recovered without complications.

Postoperative myocardial infarction in an orthognatic jaw surgery

Cardiovascular complications, in particular perioperative myocardial infarctions, are central contributors to morbidity and mortality after non-cardiac surgery. We present a case of a 41-year-old male, smoker and dyslipidemic, who underwent bimaxillary orthognathic jaw surgery with the development of an acute coronary syndrome in the immediate postoperative period. We managed to early diagnose the myocardial infarction and promptly performed a percutaneous transluminal coronary angioplasty, resulting in a positive outcome.

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.

Postoperative Critical Care of the Adult Cardiac Surgical Patient. Part I: Routine Postoperative Care

OBJECTIVES

Cardiac surgery, including coronary artery bypass, cardiac valve, and aortic procedures, is among the most common surgical procedures performed in the United States. Successful outcomes after cardiac surgery depend on optimum postoperative critical care. The cardiac intensivist must have a comprehensive understanding of cardiopulmonary physiology and the sequelae of cardiopulmonary bypass. In this concise review, targeted at intensivists and surgeons, we discuss the routine management of the postoperative cardiac surgical patient.

DATA SOURCE AND SYNTHESIS

Narrative review of relevant English-language peer-reviewed medical literature.

CONCLUSIONS

Critical care of the cardiac surgical patient is a complex and dynamic endeavor. Adequate fluid resuscitation, appropriate inotropic support, attention to rewarming, and ventilator management are key components. Patient safety is enhanced by experienced personnel, a structured handover between the operating room and ICU teams, and appropriate transfusion strategies.

Improving Nurses’ Knowledge of Continuous ST-Segment Monitoring

Background:

Continuous ST-segment monitoring can result in detection of myocardial ischemia, but in clinical practice, continuous ST-segment monitoring is conducted incorrectly and underused by many registered nurses (RNs). Many RNs are unable to correctly institute ST-segment monitoring guidelines because of a lack of education.

Purpose:

To evaluate whether an educational intervention, provided to 32 RNs, increases knowledge and correct clinical decision making (CDM) for the use of continuous ST-segment monitoring.

Methods:

At a single institution, an ST-segment monitoring class was provided to RNs in 2 cardiovascular units. Knowledge and correct CDM instruments were used for a baseline pretest and subsequent posttest after ST-segment monitoring education.

Results:

Statistical significance between pretest and posttest scores for knowledge and correct CDM practice was noted with dependent t tests (P = .0001).

Conclusions:

Many RNs responsible for electrocardiographic monitoring are not aware of evidence-based ST-segment monitoring practice guidelines and cannot properly place precordial leads needed for ST-segment monitoring. Knowledge and correct CDM with ST-segment monitoring can be improved with focused education.

Ivabradine: potential clinical applications in critically ill patients

It has been extensively demonstrated that an elevated heart rate is a modifiable, independent risk factor for cardiovascular events. A high heart rate increases myocardial oxygen consumption and reduces diastolic perfusion time. It can also increase ventricular diastolic pressures and induce ventricular arrhythmias. Critical care patients are prone to develop a stress induced cardiac impairment and consequently an increase in sympathetic tone. This in turn increases heart rate. In this setting, however, heart rate lowering might be difficult because the effects of inotropic drugs could be hindered by heart rate reducing drugs like beta-blockers. Ivabradine is a new selective antagonist of funny channels. It lowers heart rate, reducing the diastolic depolarization slope. Moreover, ivabradine is not active on sympathetic pathways, thus avoiding any interference with inotropic amines. We reviewed the literature available regarding heart rate control in critical care patients, focusing our interest on the use of ivabradine to assess the potential benefits of the drug in this particular setting.

Perioperative myocardial infraction following video-assisted thoracic surgery: A case report and review

Perioperative myocardial infarction (PMI) during video-assisted thoracoscopy (VAT) surgery is rarely reported in the literature. ST-segment-elevated myocardial infarction (STEMI) is rare in the perioperative period. We report a case of STEMI, following VAT surgery, complicated by acute coronary syndrome. A 53-year male, admitted with recurrent left-sided pneumothorax, an intercostal chest drain was inserted and planned for VAT and lung resection. The intra-operative period was stable, minimal lung resection, and excision of bullae was done. Just before extubation, patient had acute myocardial infarction and cardiogenic shock. An immediate percutaneous coronary intervention (PCI) angiogram showed 90% blockage of the right coronary artery with thrombus. Export thrombectomy and balloon angioplasty was done. Weaned off from inotropes and ventilator. He was transferred to ward from there by day 12, discharged home on double antiplatelet therapy. The PMI can occur earlier than it is commonly thought, and in our patient, it was STEMI, which is rare and occurred during VAT Surgery. In our patient early detection and earlier PCI may have resulted in better outcome.

Continuous ST-segment monitoring in the intensive care unit

This article provides evidence-based rationales to substantiate revisions of current monitoring practices and to provide realistic strategies for implementation of new practices.

Coronary artery spasm occurring in the setting of the oculocardiac reflex

The oculocardiac reflex (OCR) occurs in up to 90% of ophthalmological surgeries. Several preventive and treatment strategies have been described. Coronary artery spasm (CAS) plays an important role in the pathogenesis of variant angina and myocardial infarction. We describe an unusual case of a perioperative myocardial infarction due to CAS that occurred in the setting of the treatment of the OCR. We offer insight aimed at minimizing the deleterious effects of the OCR and its management.

[Perioperative myocardial damage in non-cardiac surgery patients]

Perioperative myocardial damage occurs with a high incidence depending on the operative procedure and the patients examined and is considered to be among the most relevant risk factors for increased perioperative morbidity and mortality in patients undergoing non-cardiac surgery. The pathophysiology of myocardial damage in the perioperative period is still not well understood. Both ischemia with and without acute coronary occlusion and non-ischemic stimuli can put a substantial strain on the heart in the perioperative period. However, in many cases the clinical presentation does not allow a clear differentiation between ischemic and non-ischemic myocardial damage. In the majority of cases perioperative myocardial infarctions occur with only mild or even without any clinical symptoms. This is probably due to a considerable difference in phenotype and pathophysiology between perioperative and non-perioperative myocardial infarctions. As a result of this unexplained etiology of perioperative myocardial infarction it remains an open question whether the contemporary diagnostic and therapeutic recommendations for the acute coronary syndrome can be extrapolated to the perioperative situation. The present review reflects the current state of knowledge and presents an optional approach to the diagnosis and therapy of perioperative myocardial injury.

How safe is my intensive care unit? Methods for monitoring and measurement

PURPOSE OF REVIEW

Patient safety is attracting increasing attention. How we monitor and measure safety, however, is not well defined. In this review we describe a conceptual model for monitoring and measuring safety, describe the development of a safety scorecard, and provide an example of how this scorecard is used in the ICU.

RECENT FINDINGS

Our safety scorecard stratifies measures into two categories. One category uses valid rate-based measures to evaluate: How often do we provide the interventions that patients should receive? (process measure); and How often do we harm patients? (outcome measure). The second category includes measures that cannot be expressed as valid rates: How do we know we learned from defects? (structural measure); and How well have we created a culture of safety? (context measure). Measures within each domain should be important and valid, and organizations should be able to use the measures to improve patient safety.

SUMMARY

We present a framework for a patient safety scorecard to measure and monitor patient safety. This safety scorecard is a valid and practical tool for ICUs to track progress of efforts to improve patient safety and answer the question, how safe is my ICU?

Monitoring patient safety

The opportunity to improve patient safety is significant and the pressure to improve it is increasing. An approach to evaluate an organization's progress with patient safety efforts has not been clearly articulated, and existing efforts to monitor safety are likely inadequate. We present a framework to monitor patient safety, combining valid rate-based measures to evaluate outcomes and processes of care, and non-rate-based measures to evaluate structure and context of care. We present an example of how the safety scorecard from this framework is used to monitor patient safety at The Johns Hopkins Hospital and in over 150 ICUs in Michigan, New Jersey, and Rhode Island.

Rapid response systems: a systematic review

CONTEXT

Rapid response systems have been advocated as a potential model to identify and intervene in patients who are experiencing deterioration on general hospital wards.

OBJECTIVE

To conduct a meta-analysis to evaluate the impact of rapid response systems on hospital mortality and cardiac arrest rates.

DATA SOURCE

We searched MEDLINE, EMBASE, and the Cochrane Library from January 1, 1990, to June 30, 2005, for all studies relevant to rapid response systems. We restricted the search to the English language and by age category (all adults: >or=19 years).

STUDY SELECTION

We selected observational and randomized trials of rapid response systems that provided empirical data on hospital mortality and cardiac arrest in control and intervention groups. We reviewed 10,228 abstracts and identified eight relevant studies meeting these criteria.

DATA SYNTHESIS

Of the included studies, five used historical controls, one used concurrent controls, and two used a cluster-randomized design. The pooled relative risk for hospital mortality comparing rapid response teams to control was 0.76 (95% confidence interval, 0.39-1.48) between the two randomized studies and 0.87 (95% confidence interval, 0.73-1.04) among the five observational studies. The pooled relative risk for cardiac arrest comparing rapid response systems to control was 0.94 (95% confidence interval, 0.79-1.13) in the single randomized study and 0.70 (95% confidence interval, 0.56-0.92) in four observational studies.

CONCLUSIONS

We found weak evidence that rapid response systems are associated with a reduction in hospital mortality and cardiac arrest rates, but limitations in the quality of the original studies, the wide confidence intervals, and the presence of heterogeneity limited our ability to conclude that rapid response systems are effective interventions. Large randomized controlled trials are needed to clarify the efficacy of rapid response systems before they should become standard of care.

Daily sedative interruption in mechanically ventilated patients at risk for coronary artery disease*

OBJECTIVES

To determine the prevalence of myocardial ischemia in mechanically ventilated patients with coronary risk factors and compare periods of sedative interruption vs. sedative infusion.

DESIGN

Prospective, blinded observational study.

SETTING

Medical intensive care unit of tertiary care medical center.

PATIENTS

Intubated, mechanically ventilated patients with established coronary artery disease risk factors.

INTERVENTIONS

Continuous three-lead Holter monitors with ST-segment analysis by a blinded cardiologist were used to detect myocardial ischemia. Ischemia was defined as ST-segment elevation or depression of >0.1 mV from baseline.

MEASUREMENTS AND MAIN RESULTS

Comparisons between periods of awakening from sedation vs. sedative infusion were made. Vital signs, catecholamine levels, and time with ischemia detected by Holter monitor during the two periods were compared. Heart rate, mean arterial pressure, rate-pressure product, respiratory rate, and catecholamine levels were all significantly higher during sedative interruption. Eighteen of 74 patients (24%) demonstrated ischemic changes. Patients with myocardial ischemia had a longer intensive care unit length of stay (17.4+/-17.5 vs. 9.6+/-6.7 days, p=.04). Despite changes in vital signs and catecholamine levels during sedative interruption, fraction of ischemic time did not differ between the time awake vs. time sedated [median [interquartile range] of 0% [0, 0] compared with 0% [0, 0] while they were sedated [p=.17]). The finding of similar fractions of ischemic time between awake and sedated states persisted with analysis of the subgroup of 18 patients with ischemia.

CONCLUSIONS

Myocardial ischemia is common in critically ill mechanically ventilated patients with coronary artery disease risk factors. Daily sedative interruption is not associated with an increased occurrence of myocardial ischemia in these patients.

Management of Perioperative Myocardial Infarction in Noncardiac Surgical Patients

Perioperative myocardial infarction (PMI) is a major cause of morbidity and mortality in patients undergoing noncardiac surgery. The incidence of PMI varies depending on the method used for diagnosis and is likely to increase as the population ages. Studies have examined different methods for prevention of myocardial infarction (MI), including the use of perioperative beta-blockers, alpha(2)-agonists, and statin therapy. However, few studies have focused on the treatment of PMI. Current therapy for acute MI generally involves anticoagulation and antiplatelet therapy, raising the potential for surgical site hemorrhage in this population. This article reviews the possible mechanisms, diagnosis, and treatment options for MI in the surgical setting. We also suggest algorithms for treatment.

Surveillance and prevention of major perioperative ischemic cardiac events in patients undergoing noncardiac surgery: a review

This is the second of 2 articles evaluating cardiac events in patients undergoing noncardiac surgery. Unrecognized myocardial infarctions (MIs) are common, and up to 50% of perioperative MIs may go unrecognized if physicians rely only on clinical signs or symptoms. In this article, we summarize the evidence regarding monitoring strategies for perioperative MI in patients undergoing noncardiac surgery. Perioperative troponin measurements and 12-lead electrocardiograms can detect clinically silent MIs and provide independent prognostic information. Currently, there are no standard diagnostic criteria for perioperative MIs in patients undergoing noncardiac surgery. We propose diagnostic criteria that reflect the unique features of perioperative MIs. Finally, we review the evidence for perioperative prophylactic cardiac interventions. There is encouraging evidence that some perioperative interventions (e.g., beta-blockers, alpha2-adrenergic agonists, statins) may prevent major cardiac ischemic events, but firm conclusions await the results of large definitive trials. The best evidence does not support a management strategy of preoperative coronary revascularization before noncardiac surgery.

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.

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.

Impact of prolonged elevated heart rate on incidence of major cardiac events in critically ill patients with a high risk of cardiac complications

OBJECTIVE

To assess the incidence of major cardiac events in critically ill patients with a high risk of cardiac complications presenting with an elevated heart rate.

DESIGN AND SETTING

Observational, retrospective study in a 15-bed medical/surgical Intensive Care Unit (ICU) at a university hospital for a period of 12 months.

PATIENTS

We studied patients with a high risk of cardiac complications, according to the revised Goldman index, who were treated for at least 36 hrs in the ICU. Patients presenting with prolonged elevated heart rate, defined as a heart rate >95 beats/min for >12 hrs in at least one 24-hr period of their ICU stay, were investigated. Cardiac high-risk patients not developing this criterion served as controls. Major cardiac events, defined as nonfatal myocardial infarction, nonfatal cardiac arrest, and cardiac related death, were the primary outcome measures.

RESULTS

From a total of 791 patients, 69 patients were assessed as cardiac high-risk patients. Of 39 patients with prolonged elevated heart rates, 19 (49%) sustained major cardiac events, whereas in the control group of 30 patients, only four patients (13%) had a major cardiac event (p = .002; odds ratio, 6.2). Patients with elevated heart rate had to be treated 4.5 days longer in the ICU (p = .01), whereas the ICU and 30-day post-ICU discharge survival rates did not differ significantly.

CONCLUSIONS

In this study, we provide evidence for an increased incidence of major cardiac events in critically ill, cardiac high-risk patients with a prolonged elevated heart rate during their ICU stay. In addition, elevated heart rate was associated with a significantly longer ICU stay.

Postoperative 12-lead ECG predicts peri-operative myocardial ischaemia associated with myocardial cell damage

Peri-operative myocardial ischaemia is the single most important risk factor for an adverse cardiac outcome after non-cardiac surgery. The present study examines whether intermittent 12-lead ECG recordings can be used as an early warning tool to identify patients suffering from peri-operative myocardial ischaemia and subsequent myocardial cell damage. Fifty-five vascular surgery patients at risk for or with a history of coronary artery disease were monitored for peri-operative myocardial ischaemia using intermittent 12-lead ECG recordings taken pre-operatively and at 15 min, 20 h, 48 h, 72 h and 84 h postoperatively. The effectiveness of the 12-lead ECG was gauged by examining concordance with continuous 3-channel Holter monitoring and capturing peri-operative myocardial ischaemia by serial analyses of creatine kinase myocardial band isoenzyme and cardiac troponin T and I. The incidence of peri-operative myocardial ischaemia detected by 12-lead ECG was 44% and was identifiable in most patients (88%) 15 min after surgery. The incidence of peri-operative myocardial ischaemia detected by continuous monitoring was 53%, with the most severe episodes occurring intra-operatively and during emergence from anaesthesia. The concordance of the 12-lead method with continuous monitoring was 72%. The concordance of creatine kinase myocardial band isoenzyme activity with the 12-lead method was 71% and with Holter monitoring 57%. The concordance of mass concentration of creatine kinase myocardial band with 12-lead ECG recordings was 75%, and the corresponding value for Holter monitoring was 68%. The concordance of cardiac troponin T and I levels with the 12-lead method was 85% and 87%, respectively, and concordance with Holter monitoring was 72% and 66%, respectively. The postoperative 12-lead ECG identified peri-operative myocardial ischaemia associated with subsequent myocardial cell damage in most patients undergoing vascular surgery.

Troponin T-values provide long-term prognosis in elderly patients undergoing non-cardiac surgery

BACKGROUND

The aim of this study was to evaluate the significance of elevated postoperative Troponin T (TnT) levels in an elderly population undergoing non-cardiac surgery.

METHODS

Five hundred and forty-six consecutive patients aged 70 years or older undergoing non-cardiac surgery of >30-min duration were enrolled in this prospective, observational study. A postoperative TnT measurement was obtained on the 5th to 7th postoperative day. Troponin T values greater than 0.02 ng ml(-1) were considered positive. Patients were followed over a 1-year period, and mortality and non-fatal cardiac events (acute myocardial infarction and coronary interventions) were recorded.

RESULTS

Troponin T concentrations greater than 0.02 ng ml(-1) were detected in 53 of the study subjects (9.7%). Eleven per cent of the patients with elevated TnT had electrocardiographic or clinical signs of myocardial ischemia. One year after surgery, 17 (32%) of the patients with abnormal TnT concentrations had died. In a multivariate Cox regression analysis adjusting for baseline and perioperative data, a TnT value >0.02 ng ml(-1) was an independent correlate of the mortality adjusted hazard ratio (HR): 14.9 (95% CI 3.7-60.3). Other independent predictors of death were tachycardia (HR, 14.9 95% CI 3.45-64.8), ASA 4 (HR, 8.1 95% CI 1.3-50.0), reoperation (HR, 6.4 95% CI 1.1-36.9), and use of diuretics (HR, 4.2 95% CI 1.3-13.8).

CONCLUSION

We conclude that elevated TnT levels in the postoperative period confer a 15-fold increase in mortality during the first year after surgery. Our findings also provide evidence that silent myocardial ischemia is common in an elderly population. Routine perioperative surveillance for TnT might therefore be of use in detecting patients at an increased risk of mortality during the first postoperative year.

How can clinicians measure safety and quality in acute care?

The demand for high quality care is increasing and warranted. Evidence suggests that the quality of care in hospitals can be improved. The greatest opportunity to improve outcomes for patients over the next quarter century will probably come not from discovering new treatments but from learning how to deliver existing effective therapies. To improve, caregivers need to know what to do, how they are doing, and be able to improve the processes of care. The ability to monitor performance, though challenging in healthcare, is essential to improving quality of care. We present a practical method to assess and learn from routine practice. Methods to evaluate performance from industrial engineering can be broadly applied to efforts to improve the quality of healthcare. One method that may help to provide caregivers frequent feedback is time series data--ie, results are graphically correlated with time. Broad use of these tools might lead to the necessary improvements in quality of care.