Determinants and importance of stress hyperglycaemia in non-diabetic patients with myocardial infarction

Glycemic control and prevention of perioperative infection

PURPOSE OF REVIEW

Hyperglycemia is common during perioperative management of surgical and critically ill patients. There is extensive ongoing study of detrimental effects associated with hyperglycemia, with several remaining unanswered questions. This review discusses recent literature on tight glucose control with insulin therapy and its effects in prevention and management of infection.

RECENT FINDINGS

Hyperglycemia affects multiple pathways of the immune system, resulting in decreased phagocytic and chemotactic functions in neutrophils and monocytes, as well as increased rates of apoptosis of the former and decreased ability of the latter to present antigen. Intensive insulin therapy has been shown to counteract many of these deleterious effects. Clinically, the benefits of tight glucose control have been evaluated in different patient populations with conclusions that remain varied. Hypoglycemia as a complication of tight glucose control continues to be an issue and has led to discontinuation of two large-scale studies. The clinical relevance of hypoglycemic events remains unclear.

SUMMARY

Hyperglycemia impairs the cellular immune system, stimulates inflammatory cytokines, and affects the microcirculation, thus increasing risk for infection and preventing normal wound healing. Additional investigation is needed to define appropriate patient populations and to develop effective treatment strategies for preventing perioperative morbidity.

Causes and consequences of hyperglycemia in critical illness

PURPOSE OF REVIEW

This article reviews recent epidemiologic and intervention studies addressing the impact of hyperglycemia on morbidity and mortality in critically ill patients. It also discusses a growing body of literature examining why elevated blood glucose occurs in hospitalized patients without previously recognized diabetes.

RECENT FINDINGS

Hyperglycemia is highly prevalent in the intensive care unit. Numerous observational studies have demonstrated the association between hyperglycemia and adverse outcomes, independent of pre-existing diabetes. Intervention trials of insulin therapy are limited but overall demonstrate that glucose lowering significantly improves outcomes. The ideal target for blood glucose and the population that would benefit most from intervention remain controversial. Less frequently studied than the consequences, the causes of hyperglycemia occurring during critical illness remain unclear. Although glucose abnormalities in hospitalized patients have traditionally been explained by mediators of stress, a growing body of evidence has examined whether underlying defects in glucose metabolism may also be important contributors.

SUMMARY

In general, evidence suggests that hyperglycemia is a potentially correctable abnormality that has deleterious effects in critically ill individuals. Hyperglycemic patients without previously recognized diabetes appear to be particularly vulnerable, and thus further examination of the mechanisms underlying the development of elevated blood glucose is warranted.

Impact of renal dysfunction and glucometabolic status on one month mortality after acute myocardial infarction

Patients with impaired glucometabolic status or renal function have a higher mortality after acute myocardial infarction. It is unclear whether this higher risk is independent or related to the quality of care. In a prospective registry, stress hyperglycaemia (SH) was defined as glucose level>140 mg/dl. Renal function was assessed by the glomerular filtration rate (GFR): normal (>/=60), mild (30-60) and severe dysfunction (<30 ml/min/1.72 m(2)). The level of risk was assessed by the TIMI risk index and the quality of care by the rate of use of five guidelines-recommended treatments. Among the 1388 patients included, 23% had diabetes, 16% had SH, renal function was normal in 55%, mildly impaired in 35% and severely impaired in 9.5%. At one month, the mortality rate was higher in patients with SH (18%) as compared with diabetics (9%) or those with normal glucometabolic status (5%). Similarly, the mortality rate was higher in those with impaired renal function. Multivariable analysis identified SH, GFR group, TIMI risk index, ST segment elevation MI and quality of care as independent predictors of one-month mortality. In patients with acute MI, SH and GFR<30 ml/min/m(2) are independent predictors of mortality after adjustment for the level of risk and acute care.

Impact of fasting glycemia on short-term prognosis after acute myocardial infarction

OBJECTIVE

The prognosis of patients with acute myocardial infarction (MI), according to the new criteria for impaired fasting glucose (IFG) (FG 100-126 mg/dl), has not been evaluated.

RESEARCH DESIGN AND METHODS

A total of 2353 patients with acute MI and surviving at d 5 after admission were analyzed for short-term morbidity and mortality. FG was obtained at d 4 and 5. Patients were classified as diabetes mellitus (known diabetes or FG > or = 126 mg/dl), high IFG (110 < or = FG < 126 mg/dl), low IFG (100 < or = FG < 110 mg/dl), and normal fasting glucose (NFG) (FG < 100 mg/dl).

RESULTS

Among the 2353 patients, 968 (41%) had diabetes mellitus, 262 (11%) had high IFG, 332 (14%) had low IFG, and 791 (34%) had NFG. Compared with NFG patients, 30-d cardiovascular mortality was increased in high but not low IFG subjects. In-hospital heart failure was increased in high IFG subjects (42 vs. 20% for NFG, P < 0.0001) but not low IFG subjects (21 vs. 20%). High IFG, but not low IFG, was an independent factor associated with 30-d cardiovascular mortality [odds ratio 2.33 (1.55-3.47)] and in-hospital heart failure [odds ratio 1.70 (1.36-2.07)]. The optimal threshold levels of FG on the receiver-operating characteristic curves were 114 and 112 mg/dl to predict mortality and in-hospital heart failure, respectively.

CONCLUSION

The present study, based on a nonselected cohort of MI patients, underscores the high prevalence of IFG (25%) and highlights the clinical relevance of 110 mg/dl, but not 100 mg/dl, as a cutoff value to define the risk for worse outcome.

Early impact of insulin treatment on mortality for hyperglycaemic patients without known diabetes who present with an acute coronary syndrome

OBJECTIVE

To determine the effect of insulin for the management of hyperglycaemia in non-diabetic patients presenting with acute coronary syndrome.

METHODS

An observational study from the MINAP (National Audit of Myocardial Infarction Project) database during 2003-5 in 201 hospitals in England and Wales. Patients were those with a final diagnosis of troponin-positive acute coronary syndrome who were not previously known to have diabetes mellitus and whose blood glucose on admission was > or = 11 mmol/l. The main outcome measure was death at 7 and 30 days.

RESULTS

Of 38,864 patients who were not previously known to be diabetic, 3835 (9.9%) had an admission glucose > or = 11 mmol/l. Of patients having a clear treatment strategy, 36% received diabetic treatment (31% with insulin). Mortality at 7 and 30 days was 11.6% and 15.8%, respectively, for those receiving insulin, and 16.5% and 22.1%, respectively, for those who did not. Compared with those who received insulin, after adjustment for age, gender, co-morbidities and admission blood glucose concentration, patients who were not treated with insulin had a relative increased risk of death of 56% at 7 days and 51% at 30 days (HR 1.56, 95% CI 1.22 to 2.0, p<0.001 at 7 days; HR 1.51, 95% CI 1.22 to 1.86, p<0.001 at 30 days).

CONCLUSION

In non-diabetic patients with acute coronary syndrome and hyperglycaemia, treatment with insulin was associated with a reduction in the relative risk of death, evident within 7 days of admission, which persists at 30 days.

Initial Serum Glucose Level as a Prognostic Factor in the First Acute Myocardial Infarction

STUDY OBJECTIVE

We assess the prognostic role of initial glucose levels in patients with a first acute myocardial infarction in the emergency department (ED).

METHODS

We conducted a 3-year retrospective cohort study. Patients with a first acute myocardial infarction were recruited from the ED of a tertiary hospital from January 1, 2001, to December 31, 2003. Initial glucose levels in the ED were stratified into 3 levels (normal < 140 mg/dL; intermediate 140 to 200 mg/dL; and high > or = 200 mg/dL). Logistic and Cox regression models were applied to estimate the 1-month short-term and 1-year long-term adverse prognoses, respectively.

RESULTS

A total of 198 eligible subjects (159 men and 39 women; mean age 63.1+/-14.2 years) were recruited. The estimated survival curves among the 3 initial glucose levels were significantly different (P=.0002). After adjustment for sex, age, diabetic status, reperfusion therapy, and infarct subtype, the adjusted odds ratio for short-term prognosis progressed with higher levels when compared with the normal level (intermediate level: odds ratio 3.87; 95% confidence interval [CI] 1.71 to 8.78; high level: odds ratio 5.16; 95% CI 1.97 to 13.51). High initial glucose level was an important risk factor for long-term adverse prognosis (hazard ratio 3.08; 95% CI 1.59 to 5.98).

CONCLUSION

A high initial glucose level in the ED is an important and independent predictor of short- and long-term adverse prognoses in patients with first acute myocardial infarction.

Hyperglycemia in acutely ill emergency patients--cause or effect?

OBJECTIVES

To clarify the benefits, risks and timing of glucose control and intensive insulin therapy in several groups, specifically the neurologic, cardiac and septic populations of patients, commonly seen in the emergency department.

METHODS

Electronic search of MEDLINE (1966-2005; once with PubMed and once with Ovid) and Embase (1980-2005) using the terms insulin and glucose combined with emergency medicine, intensive care, cardiology and emergency department.

RESULTS

There is considerable controversy in the literature surrounding the use of strict glucose control in cardiac, neurologic and septic patients. Much of this literature is non-randomized, and the timing of therapy is poorly investigated.

CONCLUSIONS

Hyperglycemia is associated with adverse outcomes in acutely ill neurologic, cardiac and septic patients, but it remains unclear whether this is a causative association. Glucose control and intensive insulin therapy may be useful in some patient subgroups; however, controlled trials of aggressive glycemic control have provided insufficient evidence to justify subjecting patients to the real risks of iatrogenic hypoglycemia. We recommend a cautious approach to the control of glucose levels in acutely ill emergency department patients, with a target glucose of below 8 to 9 mmol/L.

Fasting glucose in acute myocardial infarction: incremental value for long-term mortality and relationship with left ventricular systolic function

OBJECTIVE

Elevation of blood glucose is a common metabolic disorder among patients with acute myocardial infarction (AMI) and is associated with adverse prognosis. However, few data are available concerning the long-term prognostic value of elevated fasting glucose during the acute phase of infarction.

RESEARCH DESIGN AND METHODS

We prospectively studied the relationship between fasting glucose and long-term mortality in patients with AMI. Fasting glucose was determined after an >/=8 h fast within 24 h of admission. The median duration of follow-up was 24 months (range 6-48). All multivariable Cox models were adjusted for the Global Registry of Acute Coronary Events (GRACE) risk score.

RESULTS

In nondiabetic patients (n = 1,101), compared with patients with normal fasting glucose (<100 mg/dl), the adjusted hazard ratio for mortality progressively increased with higher tertiles of elevated fasting glucose (first tertile 1.5 [95% CI 0.8-2.9], P = 0.19; second tertile 3.2 [1.9-5.5], P < 0.0001; third tertile 5.7 [3.5-9.3], P < 0.0001). The c statistic of the model containing the GRACE risk score increased when fasting glucose data were added (0.8 +/- 0.02-0.85 +/- 0.02, P = 0.004). Fasting glucose remained an independent predictor of mortality after further adjustment for ejection fraction. Elevated fasting glucose did not predict mortality in patients with diabetes (n = 462).

CONCLUSIONS

Fasting glucose is a simple robust tool for predicting long-term mortality in nondiabetic patients with AMI. Fasting glucose provides incremental prognostic information when added to the GRACE risk score and left ventricular ejection fraction. Fasting glucose is not a useful prognostic marker in patients with diabetes.

Persistent hyperglycemia is an independent predictor of outcome in acute myocardial infarction

Background

Elevated blood glucose values are a prognostic factor in myocardial infarction (MI) patients. The unfavourable relation between hyperglycemia and outcome is known for admission glucose and fasting glucose after admission. These predictors are single measurements and thus not indicative of overall hyperglycemia. Increased persistent hyperglycemia may better predict adverse events in MI patients.

Methods

In a prospective study of MI patients treated with primary percutaneous coronary intervention (PCI) frequent blood glucose measurements were obtained to investigate the relation between glucose and the occurrence of major adverse cardiac events (MACE) at 30 days follow-up. MACE was defined as death, recurrent infarction, repeat primary coronary intervention, and left ventricular ejection fraction equal to or smaller than 30%.

Results

MACE occurred in 89 (21.3%) out 417 patients. In 17 patients (4.1%) it was a fatal event. A mean of 7.4 glucose determinations were available per patient. Mean +/- SD admission glucose was 10.1 +/- 3.7 mmol/L in patients with a MACE versus 9.1 +/- 2.7 mmol/L in event-free patients (P = 0.0024). Mean glucose during the first two days after admission was 9.0 +/- 2.8 mmol/L in patients with MACE compared to 8.1 +/- 2.0 mmol/L in event free patients (P < 0.0001). The area under the receiver operator characteristic curve was 0.64 for persistent hyperglycemia and 0.59 for admission glucose. Persistent hyperglycemia emerged as a significant independent predictor (P < 0.001).

Conclusion

Persistent hyperglycemia in MI has a stronger relation with 30-day MACE than elevated glucose at admission.

Taurine Attenuates Acute Hyperglycaemia-Induced Endothelial Cell Apoptosis, Leucocyte-Endothelial Cell Interactions and Cardiac Dysfunction

OBJECTIVES

Hyperglycaemia is implicated in microvascular inflammatory injury and subsequent cardiac injury/dysfunction. Leucocyte adhesion to the endothelium, migration into tissue and toxic metabolite release are early critical steps. Taurine is a semi-essential amino acid that is endothelial protective and restrains excess leucocyte activity by the formation of less toxic inflammatory mediators. The aim was to establish if taurine reduces acute hyperglycaemia-induced endothelial cell apoptosis and leucocyte interactions and associated cardiac abnormalities.

METHODS

Male Sprague-Dawley rats (190-250 g) were randomised to control, hyperglycaemia, and hyperglycaemia plus taurine pre-treated groups. Taurine was gavaged (200 mg/kg body weight) for 5 days. Intravenous hyperglycaemia was established which was 4 times that of baseline for the 3-hour experiment. Using intravital microscopy, mesenteric post-capillary venules were examined for leucocyte rolling, adhesion and migration every 30 min from baseline. Endothelial cell apoptosis and intracellular adhesion molecule (ICAM-1) expression were assessed. In a separate experiment, blood pressure, pulse rate, cardiac injury marker (troponin T), cardiac tissue injury and oedema were also assessed.

RESULTS

Hyperglycaemia significantly increased leucocyte adhesion and migration. Blood pressure and troponin T were also elevated significantly. Taurine prevented these cardiac changes, endothelial cell apoptosis and ICAM-1 expression.

CONCLUSIONS

Taurine may have a therapeutic role in reducing diabetic microvascular inflammatory injury and concomitant cardiac dysfunction.

Predictive value of admission hyperglycaemia on mortality in patients with acute myocardial infarction

RATIONALE AND AIM

In patients with an acute myocardial infarction, admission hyperglycaemia (AH) is a major risk factor for mortality. However, the predictive value of AH, when the risk score and use of guidelines-recommended treatments are considered, is poorly documented.

METHODS

The first fasting plasma glucose levels after admission, risk level, guidelines-recommended treatment use and 1-year mortality were recorded. Patients with first fasting glucose level after admission > 7.7 mmo/l were considered to have AH.

RESULTS

Three hundred and twenty patients with ST segment elevation myocardial infarction (STEMI) and 404 with non-ST segment elevation myocardial infarction (NSTEMI) were included. One hundred and seventy-five (24%) patients had pre-existing diabetes (diabetes group), 154 (21%) had AH (AH+ group) and the remainding 395 (55%) had neither diabetes nor AH (AH- group). The Global Registry of Acute Coronary Events (GRACE) risk score was lower in the AH- group, but the use of guidelines-recommended treatment was comparable in all groups. At 1 year, the mortality rate was higher in the AH+ group compared with the AH- group (18.8 vs. 6.1%, P < 0.01) and similar to that in the diabetes group (18.8 vs. 16.6%, P = NS). The relation between glycaemic status and mortality remained strong [AH+ vs. AH-, OR = 3.0 (1.5, 6.0) and diabetes vs. AH-, OR = 3.6 (1.7, 6.6)] after adjustment for the GRACE risk score [OR = 2.4 (1.8, 3.1) per 10% increase] and for treatment score [OR = 0.7 (0.6, 0.8) per 10% increase].

CONCLUSIONS

In patients without a history of diabetes, the presence of AH indicates an increased risk of 1-year mortality, similar to that of patients with diabetes, even when the risk score and use of guidelines-recommended treatment are controlled for.

Insulin resistance in nondiabetic patients with acute myocardial infarction

BACKGROUND

Recent studies have shown that insulin resistance (IR) is an independent predictor of early restenosis after coronary stenting. The aim of this study was to examine the effects of IR and its linkage to late loss with bare metal stenting in nondiabetic patients with acute myocardial infarction (AMI).

MATERIALS AND METHODS

We enrolled 61 nondiabetic patients with AMI who have undergone coronary stenting. Quantitative analyses of coronary angiographic data before and after the procedure and at 4 months were performed. Fasting plasma glucose (FPG) and insulin were measured every week until the subjects' hospital discharge. Stress hormones, endothelial nitric oxide synthase, tumor necrosis factor alpha, interleukin-6, leptin, and adiponectin were measured on admission and at 4 months after coronary stenting.

RESULTS

Simple linear regression analyses showed a relationship between FPG and insulin [IR group: r=0.297, P=.0428; no insulin resistance (NIR) group: r=0.539, P=.0466] and that late loss was associated with the homeostasis model assessment of IR (HOMA-IR) at 4 months (r=0.435, P=.03). At multiple regression analyses, HOMA-IR on admission in the IR group significantly correlated with thyroid-stimulating hormone, glucagon, and cortisol. The HOMA-IR at 4 months correlated with leptin.

CONCLUSIONS

Nondiabetic patients with AMI can be classified into two groups: the IR group and the NIR group. The IR consisted of the transient IR, which correlated with stress hormones, and the continuous IR, which correlated with leptin and contributed to restenosis after coronary stenting.

Glycemia in acute coronary syndromes

Diabetes is an established major factor of poor prognostis after an acute coronary syndrome. Recent studies have addressed the impact of abnormal glucose metabolism at the acute phase in patients without known diabetes. It has been found that abnormal glycemia regulation is more common than normal regulation in patients presenting with acute coronary syndrome, whatever the method used to evaluate blood glucose metabolism. High blood glucose at admission, whether fasting or not, are associated with worse outcome after an acute coronary syndrome, ie. by increased mortality and development of severe heart failure. The prognosistic value of glycemia is valuable for both short and long term outcomes. Admission glycemia measurement allows therapeutic strategies at the acute phase. Fasting glycemia and oral glucose tolerance test performed during the hospital stay discloses valuable diagnostic information and provide useful tools for secondary prevention. Moreover, fasting glycemia is a more powerful predictor for short term outcome after myocardial infarction than admission glycemia. The mechanisms by which hyperglycemia deteriorates the cardiovascular prognosis, in particular for left ventricular dysfunction, are not fully understood. Stress hyperglycemia may be a marker of extensive cardiac damage, reflecting a surge of stress hormones such as catecholamines and cortisol that participate to insulinresistance and affect fatty acid and glucose homeostasis. Recent findings also argue for a direct deleterious effect of hyperglycemia on myocardium.

Perioperative glucose control in the diabetic or nondiabetic patient

Patients with diabetes are more likely to undergo surgery than nondiabetics, and maintaining glycemic control in subjects with diabetes can be challenging during the perioperative period. Surgery in diabetic patients is associated with longer hospital stay, higher health care resource utilization, and greater perioperative mortality. In addition, several observational and interventional studies have indicated that hyperglycemia is associated with adverse clinical outcomes in surgical and critically ill patients. This paper reviews the pathophysiology of hyperglycemia during trauma and surgical stress and will provide practical recommendations for the preoperative, intraoperative, and postoperative care of diabetic patients.

Diabetes and stress hyperglycemia associated with myocardial infarctions at an urban municipal hospital: prevalence and effect on mortality

Municipal hospitals in large cities provide care for patients from immigrant and mixed ethnic communities that are at high risk for diabetes. Both diabetes and stress hyperglycemia increase the risk of adverse outcome after myocardial infarctions, and the impact of stress hyperglycemia on the outcome of myocardial infarctions in this particular setting has not been previously studied. We therefore undertook a retrospective cohort study to determine the prevalence of diabetes and stress hyperglycemia in patients presenting to a university-affiliated Bronx municipal hospital with myocardial infarction, and the relationship of these conditions to the extent of coronary disease and mortality. We obtained data on 106 consecutive patients from July 1998 to April 1999 with a diagnosis-related group diagnosis of either myocardial infarction or acute coronary syndrome, in which myocardial infarction was confirmed by serum enzymes or characteristic electrocardiographic changes. Patients were followed until March 30, 2001. Measurements of clinical parameters and results of catheterization were obtained for all patients. Death rates were determined by laboratory database, direct patient contact, or data from National Death Index. Eighty percent of the cohort had either a diagnosis of diabetes (n = 45, 42% of cohort) or evidence of stress hyperglycemia (defined as serum glucose greater than 126 mg/dL at the time of admission without prior diagnosis of diabetes, n = 40, 38%). In-hospital mortality for patients with diabetes, stress hyperglycemia, or normal glucose was 20%, 15%, and 14%, respectively. Eighty-three percent of the cohort received beta blockers, and 61% of hospital survivors had catheterization. Left main or triple vessel disease was common in both patients with diabetes (52%) and patients with stress hyperglycemia (32%). Mortality at follow up (maximum follow up 3 years; mean follow up 19.6 months) was much higher in patients with either diabetes (42%) or stress hyperglycemia (52%) than normal subjects (24%). Kaplan-Meier analysis of the difference in mortality between patients with high glucose on admission and normal subjects was borderline significant (P = 0.06). Multivariate regression demonstrated that age (P = 0.020), increase in admission serum creatinine (P = 0.001), and reduction in either ejection fraction (P = 0.016) or admission systolic blood pressure (P = 0.005) were significant predictors of mortality. Glycemic status and sex were not independently associated with death after controlling for these other factors. These results show that the prevalence of both diabetes and stress hyperglycemia on presentation with myocardial infarction is strikingly high in this immigrant, mixed ethnic, urban population. Patients with diabetes and stress hyperglycemia had advanced disease on presentation and much higher mortality at 2 to 3 years than those with normal blood glucose. The mortality difference is the result of older age and more advanced disease rather than hyperglycemia per se.

Association between blood glucose and long-term mortality in patients with acute coronary syndromes in the OPUS-TIMI 16 trial

Hyperglycemia in the context of acute coronary syndrome (ACS) is a common observation, and existing data suggest that high glucose levels are associated with increased in-hospital mortality. We assessed the relation between random glucose and long-term mortality in 9,020 patients with ACS who were enrolled in the OPUS-TIMI 16 trial. A significant relation between glucose level and 10-month mortality was observed (2.7% in quartile 1 vs 7.0% in quartile 4, p <0.0001). After multivariable adjustment for co-morbidity, which included history of diabetes, this relation remained significant (quartile 4 vs 1, hazard ratio 1.70, 95% confidence interval 1.16 to 2.50, p = 0.006). These observations were similar in the TACTICS-TIMI 18 trial. In addition, we observed that B-type natriuretic peptide and troponin I levels increased across glucose quartiles in the OPUS-TIMI 16 trial (p values for trend = 0.002 and 0.0001, respectively) and the TACTICS-TIMI 18 trial (p values for trend = 0.006 and 0.0001, respectively). High blood glucose during ACS is an independent predictor of long-term mortality and is significantly correlated with prognostic biomarkers. Glucose levels during ACS may be an important addition to the risk stratification of patients with ACS and a potentially important target for therapy.

Usefulness of combined white blood cell count and plasma glucose for predicting in-hospital outcomes after acute myocardial infarction

Admission white blood cell (WBC) count and plasma glucose (PG) have been associated with adverse outcomes after acute myocardial infarction (AMI). This study investigated the joint effect of WBC count and PG on predicting in-hospital outcomes in patients with AMI. WBC count and PG were measured at the time of hospital admission in 3,665 patients with AMI. Patients were stratified into tertiles (low, medium, and high) based on WBC count and PG. Patients with a high WBC count had a 2.0-fold increase in in-hospital mortality compared with those with a low WBC count. Patients with a high PG level had a 2.7-fold increase in mortality compared with those with a low PG level. When a combination of different strata for each variable was analyzed, a stepwise increase in mortality was seen. There was a considerable number of patients with a high WBC count and low PG level or with a low WBC count and high PG level. These patients had an intermediate risk, whereas those with a high WBC count and high PG level had the highest risk, i.e., 4.8-fold increase in mortality, compared with those with a low WBC count and low PG level. Multivariate analysis was performed to assess the predictor for in-hospital mortality using WBC count and PG level as continuous variables and showed that WBC count and PG level were independently associated with in-hospital mortality. These findings suggested that a simple combination of WBC count and PG level might provide further information for predicting outcomes in patients with AMI.

Niveles de glucemia en pacientes no diabéticos. ¿Es un factor pronóstico en el síndrome coronario agudo?

INTRODUCTION

The role of glucose elevation above levels considered normal in non- diabetic patients with acute coronary syndromes (ACS) is not adequately defined. The aim of this study was to determine the association between serum glucose at admission and 1-year mortality in this type of patients.

METHODS

We studied 648 non diabetic patients admitted consecutively with ACS. Serum glucose was determined at admission, together with classical risk factors, biochemical and inflammatory markers. The primary endpoint was all cause mortality at one year follow-up.

RESULTS

Patients with normal glucose had lower mortality than patients with impaired fasting glucose (14.1% vs 5.7% 1-year mortality) or with glucose levels in diabetic range (24.7% vs 5.7% 1-year mortality).

CONCLUSIONS

In non-ST elevation acute coronary syndromes, elevated levels of glucose in non-diabetic patients are strong predictors of all cause death at one year follow-up. This prognostic value is independent of other risk factors biochemical and inflammatory markers.

Admission blood glucose and adverse outcomes in non-diabetic patients with myocardial infarction in the reperfusion era

AIMS

To investigate the association between admission blood glucose levels and adverse outcomes after an incident acute myocardial infarction across a broad range of glucose levels in non-diabetic patients treated with modern therapy.

METHODS

The relationship between admission blood glucose and 28-day case fatality was studied in 1348 consecutively hospitalized patients with a first-ever myocardial infarction between January 1998 and December 2002 recruited from a population-based myocardial infarction registry.

RESULTS

Patients were divided into quartiles on the basis of admission glucose level. Patients with elevated admission blood glucose had more adverse baseline characteristics than patients with lower glucose levels. After multivariable adjustment the odds ratios (95% confidence interval) for 28-day case fatality among those in the second, third and fourth quartile in comparison to the first quartile were 1.55 (0.49-4.87), 3.21 (1.06-9.74), and 3.73 (1.28-10.92), respectively (p for trend=0.0054). Admission hyperglycemia was also associated with complications during hospital stay among 28-day survivors.

CONCLUSION

The risk for major complications after an incident myocardial infarction was closely related to admission blood glucose concentrations near to or within the normal range, and certainly below the diabetic threshold. Thus, admission hyperglycemia still provides an early marker of bad prognosis after an acute myocardial infarction in an era of modern therapy.

Major impact of admission glycaemia on 30 day and one year mortality in non-diabetic patients admitted for myocardial infarction: results from the nationwide French USIC 2000 study

OBJECTIVE

To analyse the short and long term prognostic significance of admission glycaemia in a large registry of non-diabetic patients with acute myocardial infarction.

METHODS

Assessment of short and long term prognostic significance of admission blood glucose in a consecutive population of 1604 non-diabetic patients admitted to intensive care units in France in November 2000 for a recent (<or= 48 hours) myocardial infarction.

RESULTS

In-hospital mortality, compared with that of patients with admission glycaemia below the median value of 6.88 mmol/l (3.7%), rose gradually with each of the three upper sextiles of glycaemia: 6.5%, 12.5% and 15.2%. Conversely, one year survival decreased from 92.5% to 88%, 83% and 75% (p < 0.001). Admission glycaemia remained an independent predictor of in-hospital and one year mortality after multivariate analyses accounting for potential confounders. Increased admission glycaemia also was a predictor of poor outcome in all clinical subsets studied: patients without heart failure on admission, younger and older patients, patients with or without reperfusion therapy, and patients with or without ST segment elevation.

CONCLUSION

In non-diabetic patients, raised admission blood glucose is a strong and independent predictor of both in-hospital and long term mortality.

Effects of glucose abnormalities on in-hospital outcome after coronary intervention for acute myocardial infarction

BACKGROUND

The effects of glucose abnormalities on outcomes after percutaneous coronary intervention (PCI) remain unclear. We examined the association between glucose abnormalities and in-hospital outcome in patients undergoing PCI for acute myocardial infarction (AMI).

METHODS AND RESULTS

A total of 849 patients with AMI who were admitted within 12 h after symptom onset and underwent emergency PCI were classified according to the presence or absence of admission hyperglycemia, defined as a blood glucose level on admission of >11 mmol/L and whether they had a history of diabetes mellitus: group 1 (n = 504), non-diabetic patients without admission hyperglycemia; group 2 (n = 111), diabetic patients without admission hyperglycemia; group 3 (n = 87), non-diabetic patients with admission hyperglycemia; and group 4 (n = 147), diabetic patients with admission hyperglycemia. Among groups 1, 2, 3 and 4, in-hospital mortality was 2.6, 2.7, 11.5 and 8.8%, respectively (p < 0.01). Multivariate analysis showed that compared with group 1 patients, the odds ratio (95%confidence interval) for in-hospital mortality among those in groups 2, 3, and 4 were 0.80 (0.24-2.60, p = 0.708), 2.29 (1.10-5.49, p = 0.039), and 2.14 (1.14-4.69, p = 0.048), respectively.

CONCLUSIONS

In-patients undergoing PCI for AMI, admission hyperglycemia, irrespective of the presence or absence of diabetes, is associated with increased in-hospital mortality, whereas diabetes without admission hyperglycemia is not.

Intensive Versus Modified Conventional Control of Blood Glucose Level in Medical Intensive Care Patients: A Pilot Study

• Background Critically ill postsurgical patients fare better with intensive control of blood glucose level. The link between glucose control and outcome is less well studied for medical intensive care patients. Whether intensive glucose control requires additional staffing is unclear.

• Objectives To compare intensive glucose control with modified conventional control in the medical intensive care unit and to assess compliance with glucose targets, incidence of hypoglycemia, and staffing adequacy.

• Methods Medical intensive care patients who had been receiving mechanical ventilation for less than 24 hours were randomized to intensive or modified conventional protocols for glucose control. Nurses were trained before participating in the study and were interviewed after its completion.

• Results Five subjects were randomized to each protocol. Mean blood glucose levels were 5.8 (SD 1.5) mmol/L (105.3 [SD 26.3] mg/dL) for the intensive group and 9.8 (SD 2.5) mmol/L (177.4 [SD 45.5] mg/dL) for the modified conventional group (P &lt; .001). Fifty percent of glucose levels met target values in the intensive group, and 72% of glucose levels met target values in the modified conventional group (P &lt; .001). Severe hypoglycemia (glucose &lt;2.2 mmol/L [&lt;40 mg/dL]) occurred rarely and without complication. Nurses suggested protocols might be improved by using smaller steps in adjusting insulin dosage and reported that simultaneously caring for more than 1 study subject was taxing.

• Conclusions Target levels for blood glucose were achieved with both protocols. Severe hypoglycemia was rare and uncomplicated regardless of type of glucose control. Additional staffing may be needed for intensive glucose control.

[Admission and fasting blood glucose are important prognostic markers in acute coronary syndromes]

This paper reviews current evidence on the role of admission and fasting glycaemia as prognostic markers in patients with acute coronary syndromes. Though both parameters are correlated, they give different prognostic information and are related to both in-hospital complications, including death, and long-term outcomes. As hyperglycemia at the acute stage of myocardial infarction is an independent predictor of untoward cardiovascular events, blood glucose measurements should become routine in all patients presenting with acute coronary syndromes.

Does hyperglycaemia precede the clinical onset of myocardial ischaemia?

Stress hyperglycaemia has been observed previously in a large proportion of patients with acute myocardial infarction. We report a patient who presented to our intensive care unit (ICU) on two occasions with acute hyperglycaemia preceding new onset myocardial ischaemia by several hours.

Optimizing Hospital Use of Intravenous Insulin Therapy: Improved Management of Hyperglycemia and Error Reduction With a New Nomogram

OBJECTIVE

To assess the efficacy and safety of intravenous (IV) insulin administration with use of our institution's old protocol (pre-nomogram phase) as compared with our new insulin nomogram (post-nomogram phase), which titrates insulin dose based on the rate of change of plasma glucose values and uses multipliers to determine the new insulin infusion rate.

METHODS

Hospitalized adults receiving an IV insulin infusion in our tertiary care medical center were enrolled in this study after informed consent was obtained. The study was an observational analysis conducted before and after implementation of the new insulin infusion nomogram. Measurements included episodes of hypoglycemia and incidence of the following errors in the insulin infusion process: (1) episodes of documented failure to increase insulin infusion rate despite persistent hyperglycemia and (2) number of times the IV infusion was stopped without subcutaneous administration of insulin.

RESULTS

Overall, 66 patients were analyzed (38 in the pre-nomogram phase and 28 in the post-nomogram phase). The new nomogram reduced by nearly 3-fold (from 0.89 +/- 0.68 to 0.36 +/- 0.49 occurrence per patient per 24 hours; P<0.001) the mean incidence of failure to give insulin subcutaneously before discontinuation of IV insulin infusion. Moreover, the nomogram nearly eliminated the error of caregiver nonresponsiveness to persistent hyperglycemia: mean incidence 0.39 +/- 0.65 occurrence per patient per 24 hours before implementation of the new nomogram versus 0.02 +/- 0.09 afterward (P<0.002). There was no statistically significant difference in episodes of hypoglycemia between the 2 study groups.

CONCLUSION

Safe IV administration of insulin through error prevention is essential. Implementation of a new IV insulin infusion nomogram, which adjusts insulin infusion using multipliers, reduces errors and improves glycemic control without increasing hypoglycemic episodes.

Admission glucose and mortality in elderly patients hospitalized with acute myocardial infarction: implications for patients with and without recognized diabetes

BACKGROUND

The relationship between admission glucose levels and outcomes in older diabetic and nondiabetic patients with acute myocardial infarction is not well defined.

METHODS AND RESULTS

We evaluated a national sample of elderly patients (n=141,680) hospitalized with acute myocardial infarction from 1994 to 1996. Admission glucose was analyzed as a categorical (< or =110, >110 to 140, >140 to 170, >170 to 240, >240 mg/dL) and continuous variable for its association with mortality in patients with and without recognized diabetes. A substantial proportion of hyperglycemic patients (eg, 26% of those with glucose >240 mg/dL) did not have recognized diabetes. Fewer hyperglycemic patients without known diabetes received insulin during hospitalization than diabetics with similar glucose levels (eg, glucose >240 mg/dL, 22% versus 73%; P<0.001). Higher glucose levels were associated with greater risk of 30-day mortality in patients without known diabetes (for glucose range from < or =110 to >240 mg/dL, 10% to 39%) compared with diabetics (range, 16% to 24%; P for interaction <0.001). After multivariable adjustment, higher glucose levels continued to be associated with a graded increase in 30-day mortality in patients without known diabetes (referent, glucose < or =110 mg/dL; range from glucose >110 to 140 mg/dL: hazard ratio [HR], 1.17; 95% CI, 1.11 to 1.24; to glucose >240 mg/dL: HR, 1.87; 95% CI, 1.75 to 2.00). In contrast, among diabetic patients, greater mortality risk was observed only in those with glucose >240 mg/dL (HR, 1.32; 95% CI, 1.17 to 1.50 versus glucose < or =110 mg/dL; P for interaction <0.001). One-year mortality results were similar.

CONCLUSIONS

Elevated glucose is common, rarely treated, and associated with increased mortality risk in elderly acute myocardial infarction patients, particularly those without recognized diabetes.

Fasting glucose is an important independent risk factor for 30-day mortality in patients with acute myocardial infarction: a prospective study

BACKGROUND

Stress hyperglycemia in patients with acute myocardial infarction has been associated with increased mortality. Most studies looked at the relationship between admission glucose (AG) and outcome; limited information is available about the clinical significance of fasting glucose (FG).

METHODS AND RESULTS

We prospectively studied the relationship between FG and 30-day mortality in 735 nondiabetic patients with acute myocardial infarction. FG (> or =8-hour fast within 24 hours of admission) and AG were measured in each patient. At 30 days, 9 deaths (2%) occurred in patients with normal FG, and 11 (10%), 14 (13%), and 31 (29%) deaths occurred in the first, second, and third tertiles of elevated FG, respectively. Compared with normal FG (<110 mg/dL), the adjusted OR for 30-day mortality progressively increased with higher tertiles of elevated FG (first tertile, 4.6; 95% CI, 1.7 to 12.7; P=0.003; second tertile, 6.4; 95% CI, 2.5 to 16.6; P<0.0001; third tertile, 11.5; 95% CI, 4.7 to 20.0; P<0.0001). Compared with patients categorized as having normal AG (<140 mg/d), the adjusted ORs for tertiles of elevated AG were as follows: first tertile, 1.4 (95% CI, 0.5 to 3.8; P=0.54); second tertile, 3.0 (95% CI, 1.3 to 7.0; P=0.01); and third tertile, 4.4 (95% CI, 2.0 to 9.7; P<0.0001). Compared with patients with normal FG and AG, the adjusted ORs for 30-day mortality were 0.71 (95% CI, 0.15 to 3.4; P=0.67) in patients with elevated AG and normal FG, 3.4 (95% CI, 1.1 to 10.4; P=0.03) for patients with normal AG glucose and elevated FG, and 9.6 (95% CI, 3.5 to 26.0; P<0.0001) for patients with both elevated FG and AG. Comparing nested models showed that including AG failed to improve the prediction of the model based on FG (chi2=5.4, 3 df, P=0.15). In contrast, the addition of FG classes to the model based on AG improved model prediction (chi2=22.4, 3 df, P<0.0001).

CONCLUSIONS

There is a graded relation between elevated FG and AG and 30-day mortality in patients with acute myocardial infarction. FG is superior to AG in the assessment of short-term risk.

Relationship of baseline glucose homeostasis to hyperglycemia during medical critical illness

STUDY OBJECTIVE

To elucidate the relationship of baseline glucose control and acute stimuli with hyperglycemia during medical critical illness.

DESIGN

Prospective cohort study.

SETTING

Medical ICU (MICU) of a university affiliated hospital.

PATIENTS

Convenience sample of 100 medical patients meeting criteria for severity of illness and anticipated length of stay and not admitted to the hospital for diabetic ketoacidosis or a hyperglycemic hyperosmolar state.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were categorized as having normal, abnormal, or unevaluable baseline glucose control based on history and glycosylated hemoglobin (HbA1c). Data collection included blood glucose measurements within 120 h of MICU admission, and dosing of norepinephrine, corticosteroids, propofol, and carbohydrates. Average blood glucose and times over glycemic thresholds were calculated using linear interpolation. Hyperglycemia (glucose > 110 mg/dL) was pervasive in all groups. Among the 51 patients with normal baseline glucose control, HbA1c was correlated with hyperglycemic time (p < 0.01, R(2) = 0.15). Multiple regression found HbA1c, age, corticosteroid dose, and carbohydrate administration independently associated with hyperglycemic time (p < 0.05 for each, total R(2) = 0.49) in these patients, while body mass index, APACHE (acute physiology and chronic health evaluation) II, norepinephrine dose, propofol dose, gender, and sepsis were not associated with time > 110 mg/dL. Among normal subjects, HbA1c was independently predictive of peak and average glucose, and the fraction of time glucose was > 150 mg/dL and > 200 mg/dL (p < 0.05 for each). Patients with abnormal baseline glucose control had significantly more hyperglycemia than patients with normal baseline control.

CONCLUSIONS

Even in patients without evidence of abnormal glucose homeostasis at baseline, hyperglycemia is common during critical illness. Time exposure to hyperglycemia is correlated with acute stressors and baseline glucose regulation, as characterized by HbA1c. Patients with low HbA1c levels are less disposed to hyperglycemia during severe illness than patients with higher, but still normal, HbA1c.

Prognostic value of admission glucose in non-diabetic patients with myocardial infarction

BACKGROUND

Patients with acute myocardial infarction (AMI) who have diabetes have an increased risk of death. In nondiabetic patients, admission glucose levels may be a predictor of survival. However, data regarding admission glucose and long-term outcome in nondiabetic patients treated with reperfusion therapy for AMI are limited.

METHODS

We investigated long-term clinical outcome in 356 consecutive nondiabetic patients with ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention or thrombolysis as reperfusion therapy. Mean follow-up time was 8 +/- 2 years. The patients were divided on the basis of admission glucose level: group 1, <7.8 mmol/L; group 2, 7.8 to 11.0 mmol/L; and group 3, > or =11.1 mmol/L.

RESULTS

Mortality rate in group 1 (n = 163) was 19.0%; in group 2 (n = 151), 26.5%; and in group 3 (n = 42), 35.7% (P <.05). Higher glucose levels were associated with larger enzymatic infarct sizes (P <.01) and more reduced residual left ventricular function (P <.05). Multivariate analysis showed that Killip class >1 at admission (OR, 2.9; 95% CI, 1.7 to 5.0; P <.001), age > or =60 years (OR, 2.4; 95% CI, 1.5 to 4.0, P =.001), thrombolysis as compared with percutaneous coronary intervention (OR, 1.7; 95% CI, 1.1 to 2.7, P =.02), admission glucose category (OR, 1.4; 95% CI, 1.0 to 1.9, P =.04), and anterior location (OR, 1.6; 95% CI, 1.0 to 2.6, 0.03) were independent predictors of long-term clinical outcome.

CONCLUSIONS

Elevated admission glucose levels in nondiabetic patients treated with reperfusion therapy for ST-segment elevation myocardial infarction are independently associated with larger infarct size and higher long-term mortality rates.

Hyperglycemia at admission to the intensive care unit is associated with elevated serum concentrations of interleukin-6 and reduced ex vivo secretion of tumor necrosis factor-alpha

OBJECTIVES

The aim of the study was to investigate the association between admission blood glucose concentrations and immune function variables and its correlation to mortality rate in patients of a medical intensive care unit.

DESIGN

Prospective, observational study.

SETTING

Medical intensive care unit of a university hospital.

PATIENTS

Patients were 189 consecutive critically ill patients in the medical intensive care unit.

INTERVENTIONS

At admission to the intensive care unit, serum concentrations of interleukin-6, interleukin-8, interleukin-10, and tumor necrosis factor-alpha were measured with immunometric assays. Additionally, ex vivo secretion of tumor necrosis factor-alpha after stimulation with lipopolysaccharide in a whole blood assay and cytometric human leukocyte antigen-DR expression on monocytes were determined in all study subjects. Simplified Acute Physiology Score II and Therapeutic Intervention Scoring System-28 were calculated for the first day in the intensive care unit.

MEASUREMENTS AND MAIN RESULTS

The relationships between blood glucose concentrations and immunologic variables were analyzed using univariate and multivariate statistical methods. Overall, 75 patients (39.7%) presented with hyperglycemia. An elevated blood glucose concentration at admission was related to an increased risk of mortality in the intensive care unit (odds ratio, 2.6; p = .009). At univariate and multivariate analysis, hyperglycemia was associated with increased serum concentrations of interleukin-6 (p < .05), a reduced ex vivo production of tumor necrosis factor-alpha (p < .01), and a history of diabetes mellitus (p < .05), whereas other clinical (including Simplified Acute Physiology Score II and Therapeutic Intervention Scoring System-28) and immunologic variables were not statistically related to blood glucose.

CONCLUSIONS

Our main findings show that admission hyperglycemia is statistically related to distinct changes of humoral and cellular immune functions. Furthermore, elevated glucose concentrations at admission are associated with increased intensive care unit mortality rate in a medical intensive care unit. Although these data do not explain cause and effect, our results provide a strong rationale for studying the immunologic effects of strict glycemic control in the intensive care unit during the course of critical illness.

Current perspectives on the use of continuous subcutaneous insulin infusion in the acute care setting and overview of therapy

Continuous subcutaneous insulin infusion (CSII), also called the insulin pump, has emerged as a safe and effective therapy in the last 20 years. Utilization of CSII in several studies has shown reductions in hypoglycemia and improvement in glycemic control compared with multiple daily injections. Diabetes mellitus is often a comorbid condition in patients requiring critical care. Surprisingly, there exist no guidelines for use of CSII in the inpatient setting, and no tested protocols for management of CSII in the hospital. With solid evidence as to the benefits of this therapy in diabetes and the heightened attention to the importance of optimal inpatient glycemic control, guidelines and tested protocols for CSII use during hospitalization are warranted. We share our own guidelines for the inpatient management of the insulin pump which has allowed our hospital to address the unique challenges that pump users present with during acute illness. A general overview of the insulin pump's history, rationale for use, patient selection, and implementation is also discussed.

Perioperative diabetic and hyperglycemic management issues

OBJECTIVE AND DESIGN

To review and discuss selected literature, expert opinion, and conventional care of the hyperglycemic perioperative or critically ill patient.

MAIN POINTS

Diabetes mellitus, the most commonly encountered perioperative endocrinopathy, continues to increase dramatically in prevalence. Diabetes is the sixth most common cause of death in the United States and significantly affects other more common causes of death such as cardiac disease and stroke. Diabetic patients commonly have microvascular and macrovascular pathology that influences their perioperative course and critical illness and increases morbidity and mortality rates during hospitalization. Since diabetics require more surgeries and receive critical care more frequently than their nondiabetic counterparts, preemptive identification and anticipation of diabetic complications and comorbidities, along with an optimized treatment plan, are the foundation for the proper intensive care of this growing patient population. Hyperglycemia occurs commonly in critically ill diabetic patients but also is frequent in those who have a history of normal glucose homeostasis. The new onset of hyperglycemia in critically ill patients is driven by excessive counterregulatory stress hormone release and high tissue and circulating concentrations of inflammatory cytokines. Aggressive glycemic management improves short- and long-term outcomes in diabetic patients with acute myocardial infarction and cardiac surgical patients. Most recently, "tight" glycemic control in both diabetic and nondiabetic hyperglycemic intensive care unit patients resulted in improved survival in selected surgical patients without excessive consequences related to hypoglycemia. The mechanisms of benefit of euglycemia appear to be multifactorial.

CONCLUSIONS

Up to 25% of patients admitted to the intensive care unit have previously diagnosed diabetes. Diabetics are most commonly admitted for treatment of complications of comorbid diseases. New-onset hyperglycemia also is common in critically ill patients, and it affects patient morbidity and mortality rates. A growing body of literature supports the benefits of tight glycemic control in certain patient populations. However, further data are needed about the optimal concentration of blood glucose, the role of maintaining euglycemia in a broader group of patients (including the medically critically ill), and the mechanisms of benefit of infused glucose and insulin.

Hyperglycemia: still an important predictor of adverse outcomes following AMI in the reperfusion era

Hyperglycemia in patients admitted to hospital with myocardial infarction has been associated with adverse outcomes. However, with the improvements in survival seen in the reperfusion era, the glycometabolic state of patients presenting with acute myocardial infarction (AMI) is often given a low priority. The aim of this study was to determine if hyperglycemia remains a significant predictor of cardiac mortality and morbidity in the reperfusion era. We conducted a retrospective review of 158 patients presenting with AMI to our institution, where reperfusion therapy is routinely administered. The glucose level on admission and other risk factors were correlated against adverse cardiac outcomes. From multi-variate logistic regression analysis, admission glucose level was a consistent predictor of mortality and morbidity for all AMI patients as well as those who were reperfused. The odds ratios (OR) of in-hospital and 6-month mortality for each 1 mmol/l increment of glucose level were 1.14 (P = 0.002) and 1.18 (P < 0.001) respectively. For patients who underwent reperfusion therapy, the OR of in-hospital and 6-month mortality for each 1 mmol/l increment of glucose level were 1.27 (P = 0.001) and 1.36 (P = 0.001), respectively. We conclude that in the reperfusion era, hyperglycemia is still associated with adverse cardiac outcomes, although it is unclear whether treatment of hyperglycemia will lead to improved outcomes.

Endocrine changes in critical illness

The homeostatic corrections that have emerged in the course of human evolution to cope with catastrophic events involve a complex multisystem endeavor, of which the endocrine contribution is an integral component. Although the repertoire of endocrine changes has been probed in some detail, discerning the vulnerabilities and failure of this system is far more challenging. The ensuing endocrine topics illustrate some of the current issues reflecting attempts to gain an improved insight and clinical outcome for critical illness.

The Importance of Normoglycemia in Critically Ill Patients

Hyperglycemia is a risk factor for adverse outcomes in acutely ill patients with and without diabetes. One third of all patients admitted to tertiary care facilities have hyperglycemia, with approximately 12% having had no prior history of diabetes. Hyperglycemia adversely affects fluid balance, predisposes to infection, morbidity following acute cardiovascular events, and increases the risk for renal failure, polyneuropathy, and mortality in ICU patients. Because traditional thought suggests hypoglycemia presents a more serious risk to critically ill patients than does hyperglycemia, clinicians are often less than aggressive in treating blood glucoses under 200 mg/dl. Current research, however, demonstrates that even modest degrees of hyperglycemia are associated with adverse outcomes in critically ill patients. Safe implementation of normoglycemia in intensive care patients can be labor intensive and requires well-formulated treatment strategies and interdisciplinary support. Therefore, understanding the importance of intensive glucose control, being comfortable with current clinical treatment modalities, and having the necessary resources to provide this type of care, are vital to critical care nursing practice today.

Prognostic value of admission plasma glucose and HbA in acute myocardial infarction

OBJECTIVE

Stress hyperglycaemia increases the risk of mortality after acute myocardial infarction in diabetic and in non-diabetic patients. We aimed to determine the contribution of admission plasma glucose and HbA(1c) on post-acute myocardial infarction prognosis.

PATIENTS AND METHODS

Admission plasma glucose and HbA(1c) were simultaneously measured in all patients consecutively hospitalized for acute myocardial infarction. Patient survival was measured on 5 and 28 days after admission. Patients were defined as having 'previously diagnosed diabetes' (personal history of diabetes defined using ADA 1997 criteria), 'no diabetes', those without previously diagnosed diabetes and HbA(1c) below 6.5%, or 'possible diabetes', i.e. those without previously diagnosed diabetes and HbA(1c) above 6.5%.

RESULTS

Of the 146 patients included, four had died by day 5 and 14 by day 28. Admission plasma glucose was higher in patients who had died by day 28 (11.7 +/- 5.8 vs. 8.0 +/- 3.3 mmol/l, P = 0.002), whereas HbA(1c) was not (6.4 +/- 1.9 vs. 6.1 +/- 0.8%, NS). Admission plasma glucose was significantly higher in those who had died by day 28 after adjustment on HbA(1c). A multivariate analysis, including sex, age and heart failure prior to acute myocardial infarction, showed that admission plasma glucose concentration was an independent predictor of survival after acute myocardial infarction. Twenty-seven of the patients had previously diagnosed diabetes and 119 had no history of diabetes. Eleven were found to have possible diabetes. Admission plasma glucose was significantly higher in previously diagnosed diabetes (11.1 +/- 5.6) than in the other groups: 7.7 +/- 2.9 in non-diabetes, 8.2 +/- 2.1 in possible diabetes (P < 0.0001). The relationship between HbA(1c)-adjusted admission plasma glucose and mortality after acute myocardial infarction was also found in the non-diabetes group.

CONCLUSIONS

Admission plasma glucose, even after adjustment on HbA(1c), is a prognostic factor associated with mortality after acute myocardial infarction. Acute rather than the chronic pre-existing glycometabolic state accounts for the prognosis after acute myocardial infarction.

The use of benzodiazepines in the treatment of chest pain: a review of the literature

Benzodiazepines, although not listed in the American Heart Association's guidelines for the treatment of chest pain, are often used to provide symptomatic relief to patients who experience chest pain. To investigate the utility of benzodiazepines in the treatment of chest pain, the pharmacologic actions and cardiovascular effects of benzodiazepines were reviewed. In addition, a literature search regarding the use of benzodiazepines to treat patients with chest pain was conducted. The results indicated that benzodiazepines reduce anxiety, pain, and cardiovascular activation. Benzodiazepines amplify gamma-aminobutyric acid (GABA) throughout the central nervous system, and act more peripherally to reduce catecholamines. In addition, preliminary evidence indicates that benzodiazepines may cause coronary vasodilatation, prevent dysrhythmias, and block platelet aggregation, though further study is needed. Both non-cardiac chest pain (associated with musculoskeletal, esophageal, neurologic, and psychiatric conditions) and cardiac chest pain (associated with acute and chronic myocardial ischemia) seem to be effectively treated with benzodiazepines. Benzodiazepines are safe and well tolerated when administered alone or in combination with other medications. Moreover, the risk of dependence is minimal when benzodiazepines are prescribed on a short-term basis. Further study of benzodiazepines in the treatment of acute chest pain is needed to confirm these favorable actions and better define their use in the acute medical setting.

Absence of inducible nitric oxide synthase reduces myocardial damage during ischemia reperfusion in streptozotocin-induced hyperglycemic mice

We investigated the role of inducible nitric oxide synthase (iNOS) on ischemic myocardial damage and angiogenic process in genetically deficient iNOS (iNOS(-/-)) mice and wild-type littermates (iNOS(+/+)), with and without streptozotocin-induced (70 mg/kg intravenously) diabetes. After ischemia (25 min) and reperfusion (120 min), both iNOS(+/+) and iNOS(-/-) diabetic mice (blood glucose 22 mmol/l) had myocardial infarct size greater than their respective nondiabetic littermates (P < 0.01). Myocardial infarct size (P < 0.05), apoptotic index (P < 0.005), and tissue levels of tumor necrosis factor (P < 0.01), interleukin-6 (P < 0.01), and interleukin-18 (P < 0.01) were higher in nondiabetic iNOS(-/-) mice compared with nondiabetic iNOS(+/+) mice. As compared with diabetic iNOS(-/-) mice, diabetic iNOS(+/+) mice showed a greater infarct size (P < 0.01) associated with the highest tissue levels of nitrotyrosine and proinflammatory cytokines, as well as apoptosis. The beneficial role of iNOS in modulating defensive responses against ischemia/reperfusion injury seems to be abolished in diabetic mice.

Insulin: an endogenous cardioprotector

This review discusses the myocardial protective property of the insulin/glucose-insulin-potassium regimen and the mechanisms involved in this beneficial action. Several recent studies suggest that insulin not only is useful to control hyperglycemia and maintain glucose homeostasis but also may have the unique property to protect the myocardium from reperfusion injury and ischemia and prevent apoptosis of myocardial cells. The insulin/glucose-insulin-potassium (GIK) regimen suppresses the production of tumor necrosis factor-alpha, interleukin-6, macrophage migration inhibitory factor and other pro-inflammatory cytokines, and free radicals; and enhances the synthesis of endothelial nitric oxide and anti-inflammatory cytokines interleukin-4 and interleukin-10. Thus, the insulin/GIK regimen brings about its cardioprotective action. This may also explain why the insulin/GIK regimen is useful in sepsis and septic shock, myocardial recovery in acute myocardial infarction, and critical illness. It is suggested that the infusion of adequate amounts of insulin to patients with acute myocardial infarction, congestive heart failure, cardiogenic shock, and critical illness preserves myocardial integrity and function and ensures rapid recovery. In view of the suppressive action of insulin on the synthesis of proinflammatory cytokines and free radicals, it is possible that the insulin/GIK regimen, when used in a timely and appropriate fashion, may also protect other tissues and organs and facilitate in the recovery of patients who are critically ill.

Effects of stress hyperglycemia on acute myocardial infarction: role of inflammatory immune process in functional cardiac outcome

OBJECTIVE

Stress hyperglycemia has been associated with increased mortality in patients with myocardial infarction (MI). We examined the association between plasma glucose levels, circulating inflammatory markers, T-cell activation, and functional cardiac outcome in patients with first MI.

RESEARCH DESIGN AND METHODS

Echocardiographic parameters, circulating levels of interleukin-18 (IL-18), C-reactive protein (CPR), and the percent of CD16-CD56, CD4/CD8, CD152, and HLA-DR expression were investigated in 108 patients with acute MI on admission to the emergency ward.

RESULTS

Our review found that 31 new hyperglycemic patients (glycemia >or=7 mmol/l) had higher infarct segment length (P < 0.05) and myocardial performance index (P < 0.02) and reduced transmitral Doppler flow (P < 0.05), pulmonary flow analysis (P < 0.02), and ejection fraction (P < 0.05) compared with 36 hyperglycemic diabetic patients and 41 normoglycemic patients. Plasma IL-18 and CRP were higher in the hyperglycemic than in the normoglycemic patients (P < 0.005), with the highest values in patients with new hyperglycemia (P < 0.05). Hyperglycemic patients had a higher percent of CD16+/CD56+ cells and CD4/CD8 ratio (P < 0.01), whereas they had lower CD152 expression (which has a negative regulatory function in T-cell activation) compared with normoglycemic patients (P < 0.001).

CONCLUSIONS

During MI, hyperglycemia is associated with increased levels of inflammatory markers, enhanced expression of cytotoxic T-cells, and reduced expression of T-cells, which are implicated in limiting the immune process. An increased inflammatory immune process seems a likely mechanism linking acute hyperglycemia to poor cardiac outcome in MI patients.

Basal glucometabolic status has an impact on long-term prognosis following an acute myocardial infarction in non-diabetic patients

OBJECTIVES

Patients with diabetes are known to have a worse prognosis after an acute myocardial infarction (AMI) compared with non-diabetic patients. The primary aim of this study was to investigate the effect of glucometabolic status on long-term prognosis in non-diabetic patients with an AMI. The second aim was to evaluate the extent to which blood glucose levels at admission depended on acute stress, assessed as serum cortisol, previous glucometabolic status, measured as haemoglobin A1c (HbA1c), or both.

DESIGN

In a prospective study of patients with an AMI, blood glucose, HbA1c and cortisol were measured at admission. Fasting blood glucose was determined before discharge and also afterwards, if necessary, for classification. Patients were followed-up for 5.5 years.

SUBJECTS

Of the 305 consecutive patients 24% were diagnosed as diabetic and 76% as non-diabetic.

MAIN OUTCOME MEASURES

Death or non-fatal myocardial re-infarction.

RESULTS

In non-diabetic patients, a Cox regression model was used. With death or re-infarction as endpoint, the following prognostic factors had an impact on event-free survival: age (P<0.001), HbA1c (P=0.002), cortisol (P<0.001) and thrombolytic treatment (P=0.001). There was a correlation between cortisol and blood glucose at admission (r=0.44, P<0.001). Fasting blood glucose day 5 showed no association with event-free survival.

CONCLUSIONS

In non-diabetic patients with AMI, admission HbA1c and cortisol were predictors for 5.5-year survival without recurrent non-fatal myocardial infarction. The glucometabolic status of importance for prognosis was detected by HbA1c but not by fasting blood glucose or admission blood glucose, of which the latter was influenced by cortisol.

Impact of acute hyperglycemia on left ventricular function after reperfusion therapy in patients with a first anterior wall acute myocardial infarction

OBJECTIVE

This study was undertaken to assess the relationship between acute hyperglycemia and left ventricular function after reperfusion therapy for acute myocardial infarction (AMI).

METHODS

This study consisted of 529 patients with a first anterior wall AMI who underwent coronary angiography followed by coronary angioplasty or thrombolysis within 12 hours after the onset of chest pain. Plasma glucose was measured at the time of hospital admission. Acute hyperglycemia was defined as plasma glucose >10 mmol/L.

RESULTS

Although acute hyperglycemia was associated with both lower acute left ventricular ejection fraction (LVEF) (46% +/- 12% vs 48% +/- 10%, P =.026) and lower predischarge LVEF (51% +/- 15% vs 56% +/- 15%, P =.001), the difference was more pronounced in the latter and the change in LVEF was significantly smaller in patients with acute hyperglycemia (4.8% +/- 11.2% vs 8.0% +/- 13.8%, P =.022). Multivariable analysis showed that there was a significant correlation between plasma glucose and impaired predischarge LVEF, even after adjustment of acute LVEF (r = -0.13, P =.005). Thirty-day mortality tended to be higher in patients with acute hyperglycemia than in patients without (7.1% vs 3.5%, P =.06). Multivariable analysis showed that plasma glucose (per 1 mmol/L increase) was an independent predictor of 30-day mortality after AMI (odds ratio 1.12, 95% CI 1.03-1.22, P =.009).

CONCLUSION

Acute hyperglycemia was independently associated with impaired left ventricular function and higher 30-day mortality after AMI. These results may provide a potential explanation for poor outcomes of patients with AMI and acute hyperglycemia.

The rationale and management of hyperglycemia for in-patients with cardiovascular disease: time for change

There is increasing evidence that aggressive glycemic control for patients admitted into the hospital improves clinical outcomes, especially for patients with cardiovascular disease. There appear to be a variety of mechanisms for this. Although hyperglycemia has been shown to result in poor wound healing and more infectious complications, especially after cardiac surgical procedures, what has become clear is that the treatment of hyperglycemia with i.v. glucose, insulin, and potassium (GIK) results in better clinical outcomes even in patients without diabetes. The mechanisms for this are not year clear, but could be related to the insulin administration, perhaps due to suppression of various cytokines or free fatty acids. The practical use of insulin in these patients requires basic understanding of the use of both i.v. and s.c. insulin. Although there are several appropriate options for both of these routes of administration, it is critical that all caregivers involved in this population's care are knowledgeable about insulin strategies.

Hypothalamo-pituitary-adrenal axis in acute myocardial infarction treated by percutaneous transluminal coronary angioplasty: effect of time of presentation

Acute myocardial infarction (AMI) is associated with a stimulation of cortisol which lasts 24 hours in patients treated by thrombolysis. Percutaneous transluminal coronary angioplasty (PTCA) is an alternative treatment for AMI which reduces the length of myocardial ischemia. Our objective was the determination of the amplitude and duration of cortisol and other hormones of the hypothalamo-pituitary-adrenal (HPA) axis release in patients undergoing PTCA. These responses were also analyzed in relation with the time of onset of AMI. The effect of coronarography with or without angioplasty in patients without AMI was also studied. Plasma ACTH, cortisol, corticotropin-releasing hormone and arginine vasopressin levels were determined during the first 48 hours in 20 patients with first AMI, treated by PTCA and in 10 patients without AMI undergoing coronarography (and angioplasty in five of them). A strong stimulation of the HPA axis was observed in AMI patients, but the duration of cortisol secretion was significantly reduced (less than 8 hours) as compared with previous studies in patients treated with thrombolysis. A clear-cut ACTH-cortisol dissociation was also observed after the third hour. ACTH and cortisol stimulation was higher in patients admitted between 04:00 h and 16:00 h than in patients admitted between 16:00 h and 04:00 h In patients without AMI, coronarography induced a moderate, but significant short-lasting ACTH and cortisol stimulation. In conclusion, our data suggest that the degree of stimulation of the HPA axis may depend upon the type of treatment and the circadian rhythm of this axis.

A single serum glucose measurement predicts adverse outcomes across the whole range of acute coronary syndromes

OBJECTIVES

To analyse the relation between serum glucose concentration and hospital outcome across the whole spectrum of acute coronary syndromes.

METHODS

This was a prospective cohort study of 2127 patients presenting with acute coronary syndromes. The patients were stratified into quartile groups (Q1 to Q4) defined by serum glucose concentrations of 5.8, 7.2, and 10.0 mmol/l. The relation between quartile group and major in-hospital complications was analysed.

RESULTS

The proportion of patients with acute myocardial infarction increased incrementally across the quartile groups, from 21.4% in Q1 to 47.9% in Q4 (p < 0.0001). The trend for frequency of in-hospital major complications was similar, particularly left ventricular failure (LVF) (Q1 6.4%, Q4 25.2%, p < 0.0001) and cardiac death (Q1 0.7%, Q4 6.1%, p < 0.0001). The relations were linear, each glucose quartile increment being associated with an odds ratio of 1.46 (95% confidence interval (CI) 1.27 to 1.70) for LVF and 1.52 (95% CI 1.17 to 1.97) for cardiac death. Although complication rates were higher for a discharge diagnosis of acute myocardial infarction than for unstable angina, there was no evidence that the effects of serum glucose concentration were different for the two groups, there being no significant interaction with discharge diagnosis in the associations between glucose quartile and LVF (p = 0.69) or cardiac death (p = 0.17). Similarly there was no significant interaction with diabetic status in the associations between glucose quartile and LVF (p = 0.08) or cardiac death (p = 0.09).

CONCLUSION

Admission glycaemia stratified patients with acute coronary syndromes according to their risk of in-hospital LVF and cardiac mortality. There was no detectable glycaemic threshold for these adverse effects. The prognostic correlates of admission glycaemia were unaffected by diabetic status and did not differ significantly between patients with acute myocardial infarction and those with unstable angina.