In-hospital mortality after acute myocardial infarction in patients with diabetes mellitus

Prognostic impact of diabetes mellitus on in-hospital mortality in patients with acute myocardial infarction complicating renal dysfunction according to age and sex

BACKGROUND

Patients with acute myocardial infarction (AMI) complicating renal dysfunction (RD) are recognized as being at high risk. Although diabetes mellitus (DM) is a major cause of RD, the prognostic impact of coexisting DM on mortality in patients with AMI complicating RD is ill-defined. This study compared the prognostic impact of coexisting DM in patients with AMI complicating RD according to both age and sex.

METHODS

A multicenter retrospective study was conducted on 2988 consecutive patients with AMI complicating RD (estimated glomerular filtration rate <60 mL/min per 1.73 m2). Multivariable Cox regression analysis was performed to investigate the effects of DM on in-hospital mortality.

RESULTS

Statistically significant interactions between age and DM and between sex and DM for in-hospital mortality were revealed in the entire cohort. Coexisting DM was identified as an independent risk factor for in-hospital mortality (hazard ratio [HR], 2.543) in young (aged <65 years), but not old (aged ≥65 years), patients. DM was identified as an independent risk factor (HR, 1.469) in male, but not female, patients. Kaplan-Meier survival curves showed that DM correlated with significantly low survival rates in patients that were young or male as compared to those who were old or female.

CONCLUSIONS

There were significant differences in the prognostic impact of DM on in-hospital mortality between young and old as well as male and female patients with AMI complicating RD. These results have implications for future research and the management of patients with DM, RD, and AMI comorbidities.

Effects of Stress Hyperglycemia on Short-Term Prognosis of Patients Without Diabetes Mellitus in Coronary Care Unit

Background: Diabetes mellitus (DM) has a high morbidity and mortality worldwide, and it is a risk factor for cardiovascular diseases. Non-diabetic stress hyperglycemia is common in severely ill patients, and it could affect prognosis. This study aimed to analyze the influence of different blood glucose levels on prognosis from the perspective of stress hyperglycemia by comparing them with normal blood glucose levels and those of patients with DM.

Methods: A retrospective study of 1,401 patients in coronary care unit (CCU) from the critical care database called Medical Information Mart for Intensive Care IV was performed. Patients were assigned to the following groups 1–4 based on their history of DM, random blood glucose, and HbA1c levels: normal blood glucose group, moderate stress hyperglycemia group, severe stress hyperglycemia group and DM group. The main outcome of this study was 30- and 90-day mortality rates. The associations between groups and outcomes were analyzed using Kaplan–Meier survival analysis, Cox proportional hazard regression model and competing risk regression model.

Results: A total of 1,401 patients in CCU were enrolled in this study. The Kaplan–Meier survival curve showed that group 1 had a higher survival probability than groups 3 and 4 in terms of 30- and 90-day mortalities. After controlling the potential confounders in Cox regression, groups 3 and 4 had a statistically significant higher risk of both mortalities than group 1, while no difference in mortality risk was found between groups 2 and 1. The hazard ratios [95% confidence interval (CI)] of 30- and 90-day mortality rates for group 3 were 2.77(1.39,5.54) and 2.59(1.31,5.12), respectively, while those for group 4 were 1.92(1.08,3.40) and 1.94(1.11,3.37), respectively.

Conclusions: Severe stress hyperglycemia (≥200 mg/dL) in patients without DM in CCU may increase the risk of short-term death, which is greater than the prognostic effect in patients with diabetes. Patients with normal blood glucose levels and moderate stress hyperglycemia (140 mg/dL ≤ RBG <200 mg/dL) had no effect on short-term outcomes in patients with CCU.

Myocardial ischaemia reperfusion injury: the challenge of translating ischaemic and anaesthetic protection from animal models to humans

Myocardial ischaemia reperfusion injury is the leading cause of death in patients with cardiovascular disease. Interventions such as ischaemic pre and postconditioning protect against myocardial ischaemia reperfusion injury. Certain anaesthesia drugs and opioids can produce the same effects, which led to an initial flurry of excitement given the extensive use of these drugs in surgery. The underlying mechanisms have since been extensively studied in experimental animal models but attempts to translate these findings to clinical settings have resulted in contradictory results. There are a number of reasons for this such as dose response, the intensity of the ischaemic stimulus applied, the duration of ischaemia and lost or diminished cardioprotection in common co-morbidities such as diabetes and senescence. This review focuses on current knowledge regarding myocardial ischaemia reperfusion injury and cardioprotective interventions both in experimental animal studies and in clinical trials.

Interaction of cardiovascular risk factors with myocardial ischemia/reperfusion injury, preconditioning, and postconditioning

Therapeutic strategies to protect the ischemic myocardium have been studied extensively. Reperfusion is the definitive treatment for acute coronary syndromes, especially acute myocardial infarction; however, reperfusion has the potential to exacerbate lethal tissue injury, a process termed "reperfusion injury." Ischemia/reperfusion injury may lead to myocardial infarction, cardiac arrhythmias, and contractile dysfunction. Ischemic preconditioning of myocardium is a well described adaptive response in which brief exposure to ischemia/reperfusion before sustained ischemia markedly enhances the ability of the heart to withstand a subsequent ischemic insult. Additionally, the application of brief repetitive episodes of ischemia/reperfusion at the immediate onset of reperfusion, which has been termed "postconditioning," reduces the extent of reperfusion injury. Ischemic pre- and postconditioning share some but not all parts of the proposed signal transduction cascade, including the activation of survival protein kinase pathways. Most experimental studies on cardioprotection have been undertaken in animal models, in which ischemia/reperfusion is imposed in the absence of other disease processes. However, ischemic heart disease in humans is a complex disorder caused by or associated with known cardiovascular risk factors including hypertension, hyperlipidemia, diabetes, insulin resistance, atherosclerosis, and heart failure; additionally, aging is an important modifying condition. In these diseases and aging, the pathological processes are associated with fundamental molecular alterations that can potentially affect the development of ischemia/reperfusion injury per se and responses to cardioprotective interventions. Among many other possible mechanisms, for example, in hyperlipidemia and diabetes, the pathological increase in reactive oxygen and nitrogen species and the use of the ATP-sensitive potassium channel inhibitor insulin secretagogue antidiabetic drugs and, in aging, the reduced expression of connexin-43 and signal transducer and activator of transcription 3 may disrupt major cytoprotective signaling pathways thereby significantly interfering with the cardioprotective effect of pre- and postconditioning. The aim of this review is to show the potential for developing cardioprotective drugs on the basis of endogenous cardioprotection by pre- and postconditioning (i.e., drug applied as trigger or to activate signaling pathways associated with endogenous cardioprotection) and to review the evidence that comorbidities and aging accompanying coronary disease modify responses to ischemia/reperfusion and the cardioprotection conferred by preconditioning and postconditioning. We emphasize the critical need for more detailed and mechanistic preclinical studies that examine car-dioprotection specifically in relation to complicating disease states. These are now essential to maximize the likelihood of successful development of rational approaches to therapeutic protection for the majority of patients with ischemic heart disease who are aged and/or have modifying comorbid conditions.

Baseline glucose and left ventricular remodeling after acute myocardial infarction

In patients with acute myocardial infarction (AMI), the mechanisms behind the increased mortality related to glucose levels (GL) are poorly understood. The main purpose of this study is to analyze the relationship between baseline glucose and left ventricular enlargement (LVE). We analyzed 52 patients with a first ST-elevation AMI <24 h of evolution. Glucose levels were obtained upon admission (median time, 3 h after the beginning of chest pain). The median GL was 123.5 mg/dl, and patients above this limit were considered hyperglycemic (n=26). Left ventricular enlargement was analyzed comparing two radionuclide ventriculographies, the first obtained within 4 days post-AMI (median, 55 h) and the second 6 months later (median, 188.5 days), taking into account the difference in the obtained end-systolic volumes. Myocardial reperfusion was evaluated comparing ST resolution between a first ECG done immediately upon hospital arrival with a second ECG performed 2 h after treatment. By univariate analysis, LVE correlated significantly with baseline hyperglycemia (P<.001), failed reperfusion by ECG criteria (P<.001), and no use of ACE inhibitors or AT1 blockers (P=.046) and aspirin (P=.046). A history of previous diabetes did not correlate significantly with LVE at 6 months. In the adjusted model, basal hyperglycemia (P<.001) and failed reperfusion (P=.001) were the only variables independently correlated with LVE. In conclusion, baseline glucose is a powerful and independent predictor of LVE after AMI, which reinforces the importance of a tight glucose control during the initial phase of the disease.

Approaches to prevention of cardiovascular complications and events in diabetes mellitus

Diabetes mellitus affects about 8% of the adult population. The estimated number of patients with diabetes, presently about 170 million people, is expected to increase by 50-70% within the next 25 years. Diabetes is an important component of the complex of 'common' cardiovascular risk factors, and is responsible for acceleration and worsening of atherothrombosis. Major cardiovascular events cause about 80% of the total mortality in diabetic patients. Diabetes also induces peculiar microangiopathic changes leading to diabetic nephropathy conducive to end-stage renal failure, and to diabetic retinopathy that may progress to vision loss and blindness. In terms of major cardiovascular events, coronary heart disease and ischaemic stroke are the main causes of morbidity and mortality in diabetic patients. Peripheral arterial disease frequently occurs, and is more likely to be conducive to critical limb ischaemia and amputation than in the absence of diabetes. Although there are a number of differences in the pathogenesis and clinical features of diabetic macroangiopathy and microangiopathy, these two entities often coexist and induce mutually worsening effects. Endothelial injury, dysfunction and damage are common starting points for both conditions. Causes of endothelial injury can be distinguished into those 'common' to nondiabetic atherothrombosis, such as hypertension, dyslipidaemia, smoking, hypercoagulability and platelet activation; and those more specific and in some cases 'unique' to diabetes and directly related to the metabolic derangement of the disease, such as (i) desulfation of glycosaminoglycans (GAGs) of the vascular matrix; (ii) formation of advanced glycation end-products (AGE) and their endothelial receptors (RAGE); (iii) oxidative and reductive stress; (iv) decline in nitric oxide production; (v) activation of the renin-angiotensin aldosterone system (RAAS); and (vi) endothelial inflammation caused by glucose, insulin, insulin precursors and AGE/RAGE. Prevention of major cardiovascular events with the antithrombotic agent aspirin (acetylsalicylic acid) is widely recommended, but reportedly underutilised in patients with diabetes. However, some data suggest that aspirin may be less effective than expected in preventing cardiovascular events and especially mortality in patients with diabetes, as well as in slowing progression of retinopathy. In contrast, a recent study found picotamide, a direct thromboxane inhibitor, to be superior to aspirin in diabetic patients. Clopidogrel was either equivalent or less active in diabetic versus nondiabetic patients, depending upon different clinical settings.Recent studies have shown that some GAG compounds are able to reduce micro- and macroalbuminuria in diabetic nephropathy, and hard exudates in diabetic retinopathy, but it is as yet unknown whether these agents also influence the natural history of microvascular complications of diabetes. Lifestyle changes and physical exercise are also essential in preventing cardiovascular events in diabetic patients. Available data on the control of the metabolic state and the main risk factors show that careful adjustment of blood sugar and glycated haemoglobin is more effective in counteracting microvascular damage than in preventing major cardiovascular events. The latter objective requires a more comprehensive approach to the whole constellation of risk factors both specific for diabetes and common to atherothrombosis. This approach includes lifestyle modifications, such as dietary changes and smoking cessation and the use of HMG-CoA reductase inhibitors (statins), which are able to correct the lipid status and to prevent major cardiovascular events independently of the baseline lipidaemic or cardiovascular status. Tight control of hypertension is essential to reduce not only major cardiovascular events but also microvascular complications. Among antihypertensive measures, blockade of the RAAS by means of ACE inhibitors or angiotensin II receptor antagonists recently emerged as a potentially polyvalent approach, not only for treating hypertension and reducing cardiovascular events, but also to prevent or reduce albuminuria, counteract diabetic nephropathy and lower the occurrence of new type 2 diabetes in individuals at risk.

Factores asociados a la mortalidad intrahospitalaria del infarto de miocardio. Resultados de un estudio observacional

BACKGROUND AND OBJECTIVE

Myocardial infarction is one of the leading causes of death in Spain. This study assesses in-hospital mortality and associated factors.

PATIENTS AND METHOD

Mortality of episodes of initial attention of myocardial infarction attended in hospitals was analyzed using the 2001 Minimum Basic Group of Data corresponding to the Community of Madrid in relation with sociodemographic, hospitals, procedures, risk factors and comorbidities. Statistical descriptive techniques and logistic regression analyses were employed to analyze the data.

RESULTS

5,306 cases of myocardial infarction were studied. 71% were men and the mean age was 68 year. 73% were admitted in high technology hospitals, 49% received coronary angiography and 29% received a stent. Mortality rate was 10.8%. Multivariable analysis showed that increase in age, presence of arrhythmias, congestive heart failure, renal failure, cardiogenic shock and cerebrovascular disease were associated with in-hospital mortality, while admission in centers attending between 100 and 300 myocardial infarction cases, use of coronary angiography and stent, and previous history of arterial hypertension, smoking and high lipid levels, appeared to be protective factors.

CONCLUSIONS

Mortality estimated with an administrative data-base is similar than the mortality estimated in studies based on clinical data sets. Mortality is associated with several variables; although some of them have been previously reported, others need further investigations to confirm their relevance.

Increased hospital expenditures in diabetic patients hospitalized for cardiovascular diseases

OBJECTIVES

To measure the impact of diabetes on hospital resource use and expenditures in patients hospitalized for cardiovascular diseases (CVD).

RESEARCH DESIGN AND METHODS

We conducted an observational study of 4865 hospitalizations for CVD over 2 years (January 1998 to December 1999). Information with respect of the presence of diabetes mellitus, length of stay, readmissions, mortality, and costs were obtained through retrospective chart review.

RESULTS

Diabetic patients accounted for 35.1% of hospital admissions (1706 admissions), 40.8% of hospital stays (23,309 days), and 39% of direct medical cost (5,735,884 euros). On average, diabetic patients had longer hospital stay (13.6+/-13.2 vs. 10.7+/-11.2 days; P<.001) and direct in-patient cost (3438+/-4308 vs. 2513+/-3384 euros; P<.001) and experienced more readmissions (relative risk: 1.67; 95% CI: 1.45-1.91) compared with nondiabetic patients. However, despite the hospital mortality rate being higher in nondiabetic patients (6.3% vs. 5.8%), these results were not statistically significant (relative risk: 1.09; 95% CI: 0.86-1.40).

CONCLUSIONS

Diabetic patients hospitalized for CVD have longer hospital stay, greater risk of short-term readmission, and are more costly than nondiabetic patients. However, in-hospital mortality risk in patients hospitalized by CVD is no greater in diabetic than in nondiabetics.