Effects of infusion of glucose-insulin-potassium on myocardial function after a recent myocardial infarction

Update on Glucose Management Among Noncritically Ill Patients Hospitalized on Medical and Surgical Wards

Hyperglycemia is a common issue affecting inpatient care. Although this is in part because of the higher rate of hospitalization among patients with preexisting diabetes, multiple factors complicate inpatient glucose management, including acute stress from illness or surgery, erratic dietary intake, and contribution of medications. It has been repeatedly demonstrated that poorly controlled blood glucose levels are associated with negative clinical outcomes, such as increased mortality, higher rate of surgical complications, and longer length of hospital stay. Given these concerns, there has been extensive study of the optimal strategy for management of glucose levels, with the bulk of existing literature focusing on insulin therapy in the intensive care unit setting. This review shifts the focus to the general adult medical and surgical wards, using clinical guidelines and sentinel studies to describe the scientific basis behind the current basal-bolus insulin-based approach to blood sugar management among noncritically ill inpatients. Patient-centered clinical trials looking at alternative dosing regimens and insulin analog and noninsulin agents, such as glucagon-like peptide-1 agonist therapies, introduce safe and effective options in the management of inpatient hyperglycemia. Data from these studies reveal that these approaches are of comparable safety and efficacy to the traditional basal-bolus insulin regimen, and may offer additional benefit in terms of less monitoring requirements and lower rates of hypoglycemia. Although existing data are encouraging, outcome studies will be needed to better establish the clinical impact of these more recently proposed approaches in an effort to broaden and improve current clinical practices in inpatient diabetes care.

Non-diabetic clinical applications of insulin

BACKGROUND

Introducing a new drug to the market is a time-consuming process, is complex, and involves consumption of a lot of resources. Therefore, discovering new uses for the old drugs (i.e. drug repurposing) benefits the patients by providing them time-tested drugs. With developments in insulin therapy still happening, it is worth keeping up to date on trends in the use of this powerful glucose-lowering agent. The aim of this article is to explore the potential non-diabetic clinical applications of insulin.

METHODS

Literature survey was carried out through the various scientific journals publishing experimental and clinical research papers regarding the diverse applications of insulin other than in diabetes mellitus. These applications include both therapeutic as well as diagnostic uses of insulin. The relevant information collected from these publications was paraphrased in the present paper.

RESULTS

On studying the literature, the non-diabetic uses of insulin include the following: wound healing, parenteral nutrition, antiaging, body building, cardioprotection in acute coronary syndromes, insulin tolerance test to test the hypothalamo-pituitary-adrenal axis functioning, cell culture, cancer treatment, organ preservation, and management of septic shock, calcium channel, β-blocker overdose and other critical illnesses in intensive care units.

CONCLUSIONS

This review attempts to survey some interesting new applications of insulin other than in diabetes mellitus.

The effect of insulin on the heart : Part 1: Effects on metabolism and function

Positive inotropic effects of insulin were described early after the isolation of insulin from the pancreas but data on the effect of insulin on the heart are conflicting. Systemic insulin administration results in a reduction in circulating free fatty acids and an improvement in myocardial glucose uptake, which causes an efficiency improvement in the myocardial cell. There is strong evidence that insulin administration results in functional improvement in dysfunctional myocardium. (Neth Heart J 2010;18:197-201.).

Hypovolaemia after glucose/insulin infusions in volunteers

High-dose intravenous infusion of 5% glucose promotes rebound hypoglycaemia and hypovolaemia in healthy volunteers. To study whether such effects occur in response to glucose/insulin, 12 healthy firemen (mean age, 39 years) received three infusions over 1-2 h that contained 20 ml of 2.5% glucose/kg of body weight, 5 ml of 10% glucose/kg of body weight with 0.05 unit of rapid-acting insulin/kg of body weight, and 4 ml of 50% glucose/kg of body weight with 1 unit of insulin/kg of body weight. The plasma glucose concentration and plasma dilution were compared at 5-10 min intervals over 4 h. Regardless of the amount of administered fluid and whether insulin was given, the plasma glucose concentration decreased to hypoglycaemic levels within 30 min of the infusion ending. The plasma dilution closely mirrored plasma glucose and became negative by approx. 5%, which indicates a reduction in the plasma volume. These alterations were only partially restored during the follow-up period. A linear relationship between plasma glucose and plasma dilution was most apparent when the infused glucose had been dissolved in only a small amount of fluid. For the strongest glucose/insulin solution, this linear relationship had a correlation coefficient of 0.77 (n=386, P<0.0001). The findings of the present study indicate that a redistribution of water due to the osmotic strength of the glucose is the chief mechanism accounting for the hypovolaemia. It is concluded that infusions of 2.5%, 10% and 50% glucose, with and without insulin, in well-trained men were consistently followed by long-standing hypoglycaemia and also by hypovolaemia, which averaged 5%. These results emphasize the relationship between metabolism and fluid balance.

Effect of glucose-insulin-potassium (GIK) infusion on biomarkers of cardiovascular risk in ST elevation myocardial infarction (STEMI): insight into the failure of GIK

Glucose-insulin-potassium (GIK) infusion favourably affects several biomarkers associated with risk in the setting of myocardial infarction (MI). In the context of a recent trial demonstrating no benefit of GIK, we assessed the impact of GIK on inflammation, neurohormonal activation and myonecrosis in ST elevation myocardial infarction (STEMI). In a local substudy of an international randomised trial, 25 patients with STEMI were randomised to receive a 24-hour infusion of GIK vs. no GIK. C-reactive protein (hs-CRP), N-terminal pro-brain natriuretic peptide (NT-proBNP) and troponin T (TnT) were assayed at baseline and at 24 hours. The two groups were well matched for baseline characteristics and infarct location. There were no statistically significant differences at baseline or at 24 hours in levels of hs-CRP, NT-proBNP or cTnT, with similar and significant increases in all three biomarkers by 24 hours in both groups. In conclusion, GIK had no discernible effect on biomarkers associated with inflammation, neurohormonal activation or myonecrosis, three pathways associated with adverse outcomes in STEMI.

Glucose-insulin and potassium infusions in septic shock

Glucose-insulin and potassium (GIK) infusions are beneficial in treating ischemic myocardial depression. Myocardial depression is also an important feature in septic shock. We describe two cases of pressor-resistant hypodynamic septic shock that responded to high-dose GIK infusions. In each case, hemodynamic profiles improved sufficiently to allow withdrawal of vasopressor agents. Further assessment of GIK in patients with hypodynamic septic shock is necessary to confirm efficacy and prognostic significance.

Glucose-insulin-potassium infusion in acute myocardial infarction: a hemodynamic study

BACKGROUND

In this study, we investigated whether adjunction of glucose-insulin-potassium (GIK) infusion to primary percutaneous coronary intervention (PCI) affects hemodynamics in patients with an acute myocardial infarction.

METHODS

Hemodynamic measurements were performed in a subset of patients (n = 81) in the GIPS 2, starting immediately after PCI and continued for 12 hours.

RESULTS

Cardiac index values were stable in both groups. During the first measurements, diastolic pulmonary artery pressure and the pulmonary capillary wedge pressure (PCWP) were significantly higher in the non-GIK group (diastolic pulmonary artery pressure 15 +/- 5 vs 18 +/- 7 mm Hg, P = .028 and PCWP 14 +/- 6 vs 18 +/- 7 mm Hg, P = .030). There was a decrease in PCWP from 18 +/- 7 to 15 +/- 6 mm Hg in the non-GIK group during the first 6 hours, whereas the pressures remained at 14 +/- 6 mm Hg in the GIK group. This difference in pattern of change did not reach statistical significance in the analysis of the interaction of PCWP by GIK group (P = .065).

CONCLUSIONS

Glucose-insulin-potassium infusion as adjunctive therapy to PCI in patients with acute myocardial infarction, without overt signs of heart failure, did not negatively affect hemodynamics.

The impact of glucose-insulin-potassium infusion in acute myocardial infarction on infarct size and left ventricular ejection fraction [ISRCTN56720616]

BACKGROUND

Favorable clinical outcomes have been observed with glucose-insulin-potassium infusion (GIK) in acute myocardial infarction (MI). The mechanisms of this beneficial effect have not been delineated clearly. GIK has metabolic, anti-inflammatory and profibrinolytic effects and it may preserve the ischemic myocardium. We sought to assess the effect of GIK infusion on infarct size and left ventricular function, as part of a randomized controlled trial.

METHODS

Patients (n = 940) treated for acute MI by primary percutaneous coronary intervention (PCI) were randomized to GIK infusion or no infusion. Endpoints were the creatinine kinase MB-fraction (CK-MB) and left ventricular ejection fraction (LVEF). CK-MB levels were determined 0, 2, 4, 6, 24, 48, 72 and 96 hours after admission and the LVEF was measured before discharge.

RESULTS

There were no differences between the two groups in the time course or magnitude of CK-MB release: the peak CK-MB level was 249 +/- 228 U/L in the GIK group and 240 +/- 200 U/L in the control group (NS). The mean LVEF was 43.7 +/- 11.0 % in the GIK group and 42.4 +/- 11.7% in the control group (P = 0.12). A LVEF < or = 30% was observed in 18% in the controls and in 12% of the GIK group (P = 0.01).

CONCLUSION

Treatment with GIK has no effect on myocardial function as determined by LVEF and by the pattern or magnitude of enzyme release. However, left ventricular function was preserved in GIK treated patients.

Comparison of myocardial perfusion after successful primary percutaneous coronary intervention in patients with ST-elevation myocardial infarction with versus without diabetes mellitus

Patients with diabetes mellitus (DM) have an adverse prognosis after ST-segment elevation myocardial infarction (STEMI). Whether DM was associated with impaired myocardial reperfusion after successful primary percutaneous coronary intervention for STEMI was investigated. Myocardial reperfusion was assessed by ST-segment resolution and myocardial blush grade (MBG). A total of 386 patients were studied, of whom 64 (17%) had DM. These patients more frequently had reduced MBG (20% vs 10%, p = 0.02) and incomplete ST-segment resolution (55% vs 35%, p = 0.02) compared with patients without DM. After multivariate analysis, DM was still associated with impaired ST resolution (odds ratio 2.1, p = 0.03) and reduced MBG (odds ratio 2.2, p = 0.03).

ST-segment elevation resolution and outcome in patients treated with primary angioplasty and glucose-insulin-potassium infusion

BACKGROUND

To evaluate the impact of adjunctive high-dose glucose-insulin-potassium (GIK) on ST-segment elevation resolution in patients with ST-segment elevation myocardial infarction (MI).

METHODS

As part of a randomized controlled trial of GIK versus no GIK in patients treated with primary percutaneous coronary intervention (PCI) for ST-elevation MI in a tertiary referral center, we analyzed ST-segment elevation resolution. Paired electrocardiographic recordings (baseline and 3 hours after primary PCI) were available in 612 (65%) of 940 patients.

RESULTS

We analyzed paired electrocardiograms of 310 patients randomized to GIK and 302 control patients. Baseline characteristics of the groups were comparable. Combined complete (>70%) and partial (30%-70%) resolution was more commonly observed in the GIK group (87%) when compared with the control group (78%), odds ratio 1.92 (95% CI 1.23-3.02, P = .004); 1-year mortality was lower in patients with combined complete and partial resolution compared with patients without resolution (3.8% vs 10.3%, P = .011). There was no difference in 1-year mortality between GIK and control patients (5.5% vs 4.3%, P = .58).

CONCLUSIONS

In patients with ST-elevation MI treated with primary PCI, addition of GIK is associated with improved ST-segment elevation resolution. ST-segment elevation resolution is related to improved 1-year survival. No benefit of GIK on 1-year outcome was observed. Future trials should investigate whether GIK-induced improvement of ST-segment elevation resolution results in more favorable clinical outcome.

Glucose-insulin-potassium and reperfusion in acute myocardial infarction: rationale and design of the Glucose-Insulin-Potassium Study-2 (GIPS-2)

BACKGROUND

The combination of reperfusion therapy and high-dose glucose-insulin-potassium (GIK) infusion seems beneficial in acute myocardial infarction (MI). Current evidence, however, is not considered conclusive.

STUDY DESIGN

The Glucose-Insulin-Potassium Study-2 (GIPS-2) will investigate whether GIK, in adjunction to reperfusion therapy, is beneficial in MI patients without signs of heart failure at admission. A total of at least 1044 patients with an acute MI treated with either thrombolysis or primary percutaneous coronary intervention will be randomized to an infusion of high-dose GIK or no infusion. The primary end point of the study is 30-day mortality. Secondary end points are mortality at 1 year, recurrence of MI, repeat intervention, and infarct size.

IMPLICATIONS

If high-dose GIK significantly reduces mortality at 30 days in all patients, the adjunction of this treatment to reperfusion therapy may become part of standard regimen for patients with acute MI without heart failure.

Recombinant glucagon-like peptide-1 increases myocardial glucose uptake and improves left ventricular performance in conscious dogs with pacing-induced dilated cardiomyopathy

BACKGROUND

The failing heart demonstrates a preference for glucose as its metabolic substrate. Whether enhancing myocardial glucose uptake favorably influences left ventricular (LV) contractile performance in heart failure remains uncertain. Glucagon-like peptide-1 (GLP-1) is a naturally occurring incretin with potent insulinotropic effects the action of which is attenuated when glucose levels fall below 4 mmol. We examined the impact of recombinant GLP-1 (rGLP-1) on LV and systemic hemodynamics and myocardial substrate uptake in conscious dogs with advanced dilated cardiomyopathy (DCM) as a mechanism for overcoming myocardial insulin resistance and enhancing myocardial glucose uptake.

METHODS AND RESULTS

Thirty-five dogs were instrumented and studied in the fully conscious state. Advanced DCM was induced by 28 days of rapid pacing. Sixteen dogs with advanced DCM received a 48-hour infusion of rGLP-1 (1.5 pmol x kg(-1) x min(-1)). Eight dogs with DCM served as controls and received 48 hours of a saline infusion (3 mL/d). Infusion of rGLP-1 was associated with significant (P<0.02) increases in LV dP/dt (98%), stroke volume (102%), and cardiac output (57%) and significant decreases in LV end-diastolic pressure, heart rate, and systemic vascular resistance. rGLP-1 increased myocardial insulin sensitivity and myocardial glucose uptake. There were no significant changes in the saline control group.

CONCLUSIONS

rGLP-1 dramatically improved LV and systemic hemodynamics in conscious dogs with advanced DCM induced by rapid pacing. rGLP-1 has insulinomimetic and glucagonostatic properties, with resultant increases in myocardial glucose uptake. rGLP-1 may be a useful metabolic adjuvant in decompensated heart failure.

Insulin induced increase in coronary flow reserve is abolished by dexamethasone in young men with uncomplicated type 1 diabetes

OBJECTIVE

To examine the role of the sympathetic nervous system in regulating insulin's action on coronary perfusion in uncomplicated type 1 diabetes by blocking centrally mediated sympathetic activity with dexamethasone.

METHODS

Positron emission tomography and oxygen 15 labelled water were used to quantify myocardial blood flow basally and during adenosine infusion with or without simultaneous euglycaemic physiological hyperinsulinaemia in nine non-smoking men with type 1 diabetes and 12 healthy non-diabetic men. Each patient was studied both with and without previous dexamethasone treatment for two days (2 mg/day).

RESULTS

Insulin increased coronary flow reserve in diabetic (from 4.3 (0.7) to 5.1 (0.6), p < 0.05) and non-diabetic (from 4.3 (0.3) to 5.4 (0.4), p < 0.05) patients. In contrast to non-diabetic patients dexamethasone pretreatment abolished the insulin induced increase in coronary flow reserve in diabetic patients (p < 0.05) leading to lower coronary flow reserve in diabetic than in non-diabetic patients (3.9 (0.6) v 7.1 (0.9), p < 0.05).

CONCLUSIONS

These results show that insulin's ability to modulate coronary perfusion is sustained in young patients with type 1 diabetes without microvascular complications or autonomic neuropathy. Dexamethasone treatment abolished the insulin induced increase in coronary flow reserve in diabetic patients but not in healthy study participants, suggesting that sympathetic activation plays an important part in regulating insulin's effects on myocardial perfusion in patients with type 1 diabetes.

Effects of glucose-insulin-potassium infusion on chronic ischaemic left ventricular dysfunction

BACKGROUND

Glucose-insulin-potassium (GIK) infusion improves cardiac function and outcome during acute ischaemia.

OBJECTIVE

To determine whether GIK infusion benefits patients with chronic ischaemic left ventricular dysfunction, and if so whether this is related to the presence and nature of viable myocardium.

METHODS

30 patients with chronic ischaemic left ventricular dysfunction had dobutamine echocardiography and were given a four hour infusion of GIK. Segmental responses were quantified by improvement in wall motion score index (WMSI) and peak systolic velocity using tissue Doppler. Global responses were assessed by left ventricular volume and ejection fraction, measured using a three dimensional reconstruction. Myocardial perfusion was determined in 15 patients using contrast echocardiography.

RESULTS

WMSI (mean (SD)) improved with dobutamine (from 1.8 (0.4) to 1.6 (0.4), p < 0.001) and with GIK (from 1.8 (0.4) to 1.7 (0.4), p < 0.001); there was a similar increment for both. Improvement in wall motion score with GIK was observed in 55% of the 62 segments classed as viable by dobutamine echocardiography, and in 5% of 162 classed as non-viable. There was an increment in peak systolic velocity after both dobutamine echocardiography (from 2.5 (1.8) to 3.2 (2.2) cm/s, p < 0.01) and GIK (from 3.0 (1.6) to 3.5 (1.7) cm/s, p < 0.001). The GIK effects were not mediated by changes in pulse, mean arterial pressure, lactate, or catecholamines, nor did they correlate with myocardial perfusion. End systolic volume improved after GIK (p = 0.03), but only in 25 patients who had viable myocardium on dobutamine echocardiography.

CONCLUSIONS

In patients with viable myocardium and chronic left ventricular dysfunction, GIK improves wall motion score, myocardial velocity, and end systolic volume, independent of effects on haemodynamics or catecholamines. The response to GIK is observed in areas of normal and abnormal perfusion assessed by contrast echocardiography.

Glucose-insulin-potassium solution for acute myocardial infarction

OBJECTIVE

To review the role of glucose-insulin-potassium (GIK) solution in the management of acute myocardial infarction (AMI).

DATA SOURCES

MEDLINE (1966-October 2001) database, using the search terms glucose, insulin, potassium, and myocardial infarction.

STUDY SELECTION

Relevant English-language human studies and meta-analyses.

DATA SYNTHESIS

Most studies that have investigated the use of GIK in AMI have been from the prethrombolytic era. Although most data trended toward favoring GIK in improving mortality and morbidity of AMI, the Polish GIK study was terminated prematurely because of an increase in mortality in patients treated with GIK. Dosage, duration of treatment, and route of administration of GIK varied among studies.

CONCLUSIONS

Until results from larger-scale studies become available, the routine use of GIK infusion in AMI patients is not recommended.

Dose-dependent vasodilating effects of insulin on adenosine-stimulated myocardial blood flow

In the peripheral vasculature, insulin induces time- and dose-dependent vasodilation. We have recently demonstrated that insulin potentiates adenosine-stimulated myocardial blood flow. However, it is unknown whether insulin's effects on the coronary vasculature are dose dependent. In this study, we quantitated myocardial blood flow and adenosine-stimulated coronary flow (140 microg.kg(-1).min(-1) for 5 min) in 10 healthy men (age, 32 +/- 6 years; BMI, 24.1 +/- 1.8 kg/m(2)) using positron emission tomography and (15)O-labeled water. Hyperemic myocardial blood flow was measured in the basal state, during euglycemic physiological hyperinsulinemia (serum insulin approximately 65 mU/l) and during supraphysiological hyperinsulinemia (serum insulin approximately 460 mU/l). Basal myocardial blood flow was 0.84 +/- 0.17 ml.g(-1).min(-1). Physiological hyperinsulinemia increased the adenosine-stimulated flow by 20% (from 3.92 +/- 1.17 to 4.72 +/- 0.96 ml.g(- 1).min(-1); P < 0.05). Supraphysiological hyperinsulinemia further enhanced the adenosine-stimulated flow by 19% (to 5.61 +/- 1.03 ml.g(-1).min(-1); P < 0.05). These effects were not explained by changes in systemic hemodynamics, since coronary resistance decreased during each insulin infusion (P < 0.05). In addition, hyperemic myocardial blood flow responses during insulin stimulation were positively correlated with whole-body glucose uptake. The results demonstrate that insulin is able to enhance hyperemic myocardial blood flow in a dose-dependent manner in healthy subjects. These effects might contribute to the known beneficial dose-dependent effects of insulin on myocardial ischemia.

Is insulin an antiinflammatory molecule?

I suggest that insulin suppresses the secretion and antagonizes the harmful effects of tumor necrosis factor-alpha, macrophage migration-inhibitory factor, and superoxide anion. Therefore, the glucose-insulin-potassium regimen might be beneficial in acute myocardial infarction and useful in the management of patients with septicemia, septic shock, and other inflammatory diseases in which tumor necrosis factor-alpha and macrophage migration-inhibitory factor have important roles.

Is insulin an endogenous cardioprotector?

Stress hyperglycemia and diabetes mellitus with myocardial infarction are associated with increased risk for in-hospital mortality, congestive heart failure, or cardiogenic shock. Hyperglycemia triggers free radical generation and suppresses endothelial nitric oxide generation, and thus initiates and perpetuates inflammation. Conversely, insulin suppresses production of tumor necrosis factor-alpha and free radicals, enhances endothelial nitric oxide generation, and improves myocardial function. It is proposed that the balance between insulin and plasma glucose levels is critical to recovery and/or complications that occur following acute myocardial infarction and in the critically ill. Adequate attention should be given to maintaining euglycemia (plasma glucose <or= 110 mg/dl) in order to reduce infarct size and improve cardiac function while using a glucose-insulin-potassium cocktail.

Nitric oxide: does it play a role in the heart of the critically ill?

Nitric oxide regulates many aspects of myocardial function, not only in the normal heart but also in ischemic and nonischemic heart failure, septic cardiomyopathy, cardiac allograft rejection, and myocarditis. Accumulating evidence implicates the endogenous production of nitric oxide in the regulation of myocardial contractility, distensibility, heart rate, coronary vasodilation, myocardial oxygen consumption, mitochondrial respiration, and apoptosis. The effects of nitric oxide promote left ventricular mechanical efficiency, ie, appropriate matching between cardiac work and myocardial oxygen consumption. Most of these beneficial effects are attributed to the low physiologic concentrations generated by the constitutive endothelial or neuronal nitric oxide synthase. By contrast, inducible nitric oxide synthase generates larger concentrations of nitric oxide over longer periods of time, leading to mostly detrimental effects. In addition, the recently identified beta3-adrenoceptor mediates a negative inotropic effect through coupling to endothelial nitric oxide synthase and is overexpressed in heart failure. An imbalance between beta 1 and beta2-adrenoceptor and beta3-adrenoceptor, with a prevailing influence of beta3-adrenoceptor, may play a causal role in the pathogenesis of cardiac diseases such as terminal heart failure. Likewise, changes in the expression of endothelial nitric oxide synthase or inducible nitric oxide synthase within the myocardium may alter the delicate balance between the effects of nitric oxide produced by either of these isoforms. New treatments such as selective inducible nitric oxide synthase blockade, endothelial nitric oxide synthase promoting therapies, and selective beta3-adrenoceptor modulators may offer promising new therapeutic approaches to optimize the care of critically ill patients according to their stage and specific underlying disease process.

Metabolic effects of glucose-insulin infusions: myocardium and whole body

In target organs, insulin switches substrate utilization from free fatty acids to glucose, a change that: (i) is oxygen-efficient; (ii) repletes glycogen stores; (iii) removes potentially toxic fatty acids; and (iv) restores intracellular potassium. During or after an ischaemic challenge, the insulin metabolic mode should protect cellular functions provided that insulin can reach the ischaemic tissue. Insulin, however, also exerts non-metabolic effects, such as membrane hyperpolarization, the stimulation of adrenergic activity, and inhibition of parasympathetic tone, which may counter its beneficial metabolic actions. The net balance between the favourable and unfavourable effects of insulin on ischaemic tissues depends on: (i) the dose-response of the various effects; (ii) the presence of insulin resistance; (iii) the coexistence of hyperglycaemia; and (iv) the stage of ischaemic tissue damage. At present, a role for glucose-insulin-potassium infusions in clinical practice seems to be clearly established in the case of diabetic patients with acute coronary syndromes, and in patients undergoing urgent or elective cardiac surgery. Its role as an adjunctive therapy in the management of myocardial infarction in non-diabetic individuals has been tested in several clinical trials; however, the evidence emerging from them is inconclusive.