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

Enhancing Glycolysis Protects against Ischemia-Reperfusion Injury by Reducing ROS Production

After myocardial ischemia-reperfusion, fatty acid oxidation shows fast recovery while glucose oxidation rates remain depressed. A metabolic shift aimed at increasing glucose oxidation has shown to be beneficial in models of myocardial ischemia-reperfusion. However, strategies aimed at increasing glucose consumption in the clinic have provided mixed results and have not yet reached routine clinical practice. A better understanding of the mechanisms underlying the protection afforded by increased glucose oxidation may facilitate the transfer to the clinic. The purpose of this study was to evaluate if the modulation of reactive oxygen species (ROS) was involved in the protection afforded by increased glucose oxidation. Firstly, we characterized an H9C2 cellular model in which the use of glucose or galactose as substrates can modulate glycolysis and oxidative phosphorylation pathways. In this model, there were no differences in morphology, cell number, or ATP and PCr levels. However, galactose-grown cells consumed more oxygen and had an increased Krebs cycle turnover, while cells grown in glucose had increased aerobic glycolysis rate as demonstrated by higher lactate and alanine production. Increased aerobic glycolysis was associated with reduced ROS levels and protected the cells against simulated ischemia-reperfusion injury. Furthermore, ROS scavenger N-acetyl cysteine (NAC) was able to reduce the amount of ROS and to prevent cell death. Lastly, cells grown in galactose showed higher activation of mTOR/Akt signaling pathways. In conclusion, our results provide evidence indicating that metabolic shift towards increased glycolysis reduces mitochondrial ROS production and prevents cell death during ischemia-reperfusion injury.

Prediction of 1-Year Mortality With Different Measures of ST-Segment Recovery in All-Comers After Primary Percutaneous Coronary Intervention for Acute Myocardial Infarction

Background—

Post hoc analyses from several randomized, controlled trials have established the prognostic importance of different measures of ST-segment recovery in highly selected patients undergoing primary percutaneous coronary intervention (PCI) for ST-segment–elevation myocardial infarction (STEMI). In this single-center registry, we investigated whether various measures of ST-segment recovery can be applied to unselected STEMI patients undergoing primary PCI.

Methods and Results—

We analyzed 12-lead ECGs from 2124 consecutive STEMI patients who underwent primary PCI at our institution between November 1, 2000, and January 1, 2007. ECGs were recorded at the catheterization laboratory immediately before arterial puncture and at the end of PCI. We examined measures assessing ST-segment recovery on the postprocedural ECG and measures comparing both ECGs and related these to 1-year, all-cause mortality. Cumulative ST-segment recovery (∑ST-D resolution) at a 50% cutoff had the highest unadjusted accuracy (C statistic, 0.646; 95% confidence interval, 0.602 to 0.689; P <0.001) as compared with the other 8 measures evaluated. Furthermore, ∑ST-D resolution was the strongest contributor to both the net reclassification and integrated discrimination improvement.

Conclusions—

Although each measure of ST-segment recovery provided univariable prognostic information, the ∑ST-D resolution measure comparing summed ST-segment deviations on the preprocedural and postprocedural ECG was the best independent predictor of 1-year mortality in all-comer STEMI patients after primary PCI.

Hyperglycemia during acute myocardial infarction in patients who are treated by primary percutaneous coronary intervention: impact on long-term prognosis

BACKGROUND

Transient hyperglycemia is common during acute myocardial infarction in non-diabetic patients and is associated with a worse outcome. There is limited data on the outcome of patients who undergo primary percutaneous coronary intervention and have transient hyperglycemia.

METHODS

Fasting plasma glucose was measured in 431 consecutive acute myocardial infarction patients who underwent primary percutaneous coronary interventions. Patients were classified into three groups: non-diabetics/non-hyperglycemic (NDNH, glucose < 126 mg/dL; n=224); non-diabetics/hyperglycemic (NDH, glucose > or = 126 mg/dL; n=119); and diabetics (n=88). Data were analyzed according to the different groups and according to exact glucose levels.

RESULTS

In-hospital mortality was significantly lower in NDNH (1%) compared to NDH (8%) and diabetic (5%) patients (p=0.01). One-year cumulative mortality was highest (10%) in patients with NDH (p<0.001). One year target lesion revascularization rates were identical in NDNH and NDH patients (6% vs. 8%) and higher in diabetic patients (19%, p=0.001). In a multivariate model, a striking increase in the risk of death (0.6%, p=0.05) and target lesion revascularization (2%, p<0.0001) was found for every increment of 1 mg/dL in glucose level.

CONCLUSIONS

Transient hyperglycemia in non-diabetic acute myocardial infarction patients who undergo primary percutaneous coronary interventions is associated with high one-year mortality. One year target lesion revascularization rates were significantly higher in diabetics compared to non-diabetics with normoglycemia or transient hyperglycemia.

Glucose, insulin and myocardial ischaemia

PURPOSE OF REVIEW

The importance of glucose metabolism and insulin therapy during myocardial ischaemia is increasingly being investigated. Insulin is used to achieve a tight glucose control or as part of glucose-insulin-potassium therapy. We have reviewed (1) the physiological and physiopathological consequences of hyperglycaemia focusing on potential machanisms of myocardial ischaemia, (2) the effects of insulin on vascular tone, on the release of free fatty acids, on inflammatory pathways, on the switch of energy source and on apoptosis, and (3) clinical data reporting the effects of intensive insulin therapy and glucose-insulin-potassium solutions during myocardial ischaemia and ischaemic heart failure.

RECENT FINDINGS

In addition to its known toxic cellular effects, hyperglycaemia increases the activity of inducible nitric oxide synthase and promotes inflammation. Conversely insulin exerts anti-inflammatory and anti-apoptotic effects. Glucose-insulin-potassium solutions could improve survival after acute myocardial infarction or after surgery, according to recent meta-analyses, but confirmation of these data is eagerly awaited.

SUMMARY

Hyperglycaemia is toxic, while insulin is beneficial during acute myocardial ischaemia. Some recent evidence confirms a substantial benefit of insulin administered either alone to achieve a tight glucose control or as a component of glucose-insulin-potassium therapy. Further research is needed to confirm that tendency and to define the threshold of tight glucose control.