Glycosylated hemoglobin is associated with decreased endothelial function, high inflammatory response, and adverse clinical outcome in non-diabetic STEMI patients.

OBJECTIVE: Chronic dysglycemia was recently identified as a predictor for adverse outcomes in patients with ST-elevation myocardial infarction (STEMI) treated by percutaneous coronary intervention. Data for non-diabetic patients who underwent thrombolysis is scarce. In this context, we aimed to study the effect of HbA1c on cardiovascular outcome after STEMI. METHODS: A prospective cohort of 326 non-diabetic STEMI individuals was used for the analyses. We measured plasma glucose, hemoglobin A1c [HbA1c], lipid profile, C-reactive protein (CRP), and nitrate/nitrite (NOx) upon admission and five days after STEMI (D5). Flow-mediated dilation (FMD) was performed 30 days after STEMI. During clinical follow-up, we assessed patients for incident diabetes (progression to HbA1c ≥ 6.5%) and major adverse cardiac events (MACE), defined as a composite of fatal and non-fatal MI, sudden cardiac death, and angina requiring hospitalization. RESULTS: Using ROC-curve analysis, a 5.8% HbA1c best predicted MACE with a sensitivity of 75% and specificity of 53% (AUC 0.673, p = 0.001). Patients were categorized as high HbA1c if ≥ 5.8% and low HbA1c if <5.8%. Compared with patients with low HbA1c, those with high HbA1c presented with 20% higher CRP-D5 (p = 0.009) and 19% higher ΔCRP (p = 0.01), a 32% decrease in ΔNOx (p < 0.001), and 33% lower FMD (p < 0.001). After a median follow-up of 1.9 (1.1-2.8) years, patients with high HbA1c had more incident diabetes (HR 2.3 95% CI 1.01-5.2; p = 0.048) and MACE (HR 3.32 95% CI 1.09-10.03; p = 0.03). CONCLUSION: Non-diabetic STEMI patients with high HbA1c present with decreased endothelial function and increased inflammatory response and long-term risk of MACE.

Endothelial nitric oxide synthase genotypes modulate peripheral vasodilatory properties after myocardial infarction.

BACKGROUND: Studies in population genetics suggest an important relationship between the eNOS G894T polymorphism and occurrence of acute myocardial infarction (AMI), with little known on its influence on the post-AMI period. AIM: To investigate the association of allelic variants produced by the G894T transversion in eNOS (rs1799983) with post-AMI variables. METHODS: Cross-sectional analyses of anthropometric, clinical and laboratory assessments obtained within the first 24h and after 5 and 30 days of the AMI event across T carriers and G homozygotes of eNOS in 371 consecutive cases of AMI with ST-segment elevation admitted to a Brazilian emergency service in cardiology. Genotypes were determined by polymerase chain reaction followed by enzymatic restriction. RESULTS: Despite no difference between genotypic groups on aspects as Killip-Kimbal classification scores, extension of infarcted mass, lipid profile or pattern of medication use, an increase in serum nitric oxide from admission to day 5 was higher for T carriers (p<0.001). Thirty days post-AMI, peripheral blood flow reserve was larger among T carriers either by flow- (p=0.037) and nitrate-mediated (p=0.040) dilation testing. CONCLUSION: Our results suggest an association of the eNOS 894T allele with an apparent improvement in late arterial function in post-AMI patients.

Validation of surrogate indexes of insulin sensitivity in acute phase of myocardial infarction based on euglycemic-hyperinsulinemic clamp.

The decrease in insulin sensitivity (IS) during myocardial infarction (MI) is recognized as a possible contributor to poor patient outcomes. Despite its potential relevance, a standardized and convenient IS assessment tool has yet to be established for said clinical scenarios. This study aimed to validate the accuracy of surrogate indexes in determining IS in acute MI patients by comparison with the gold standard reference method for measuring IS, the euglycemic-hyperinsulinemic clamp (EHC). We performed EHCs in 31 consecutive nondiabetic patients who were admitted within the first 24 h of symptoms of ST-segment elevation MI. Patients with prior diagnosis of diabetes, use of hypoglycemic agents, or a glycosylated hemoglobin ≥6.5% were excluded. EHCs were performed at the second day (D2) and sixth day (D6) post-MI. Basal (12-h fasting) blood samples from D2 and D6 were used to evaluate patient blood glucose and insulin levels. We then calculated the following surrogate indexes: homeostatic model assessment of insulin sensitivity (HOMA2S), homeostatic model assessment of insulin resistance (HOMA-IR), and quantitative insulin sensitivity check index (QUICKI). The IS index measured by EHC (ISiclamp) was correlated to HOMA2S, HOMA-IR, and QUICKI at D2 (r = 0.485, P = 0.009; r = -0.384, P = 0.048; r = 0.479, P = 0.01, respectively) and D6 (r = 0.621, P = 0.002; r = -0.576, P = 0.006; r = 0.626, P = 0.002, respectively). Receiver operator characteristic curves made for discrimination of ISiclamp above the median in D2 and D6 depicted areas under the curve of 0.740, 0.734, and 0.760 for HOMA2S, HOMA-IR, and QUICKI, respectively. Bland-Altman plots displayed no apparent systematic error for indexes, but a propensity for proportional error, particularly with HOMA-IR. Thus, based on EHC, these simple surrogate indexes are feasible for assessing IS during MI.

High-density lipoprotein levels are strongly associated with the recovery rate of insulin sensitivity during the acute phase of myocardial infarction: a study by euglycemic hyperinsulinemic clamp.

BACKGROUND: The decrease of insulin sensitivity (IS) during myocardial infarction (MI) is strongly associated with increased morbidity and mortality. Recent data suggest that in individuals under stable conditions, high-density lipoprotein (HDL) may improve IS. To date, the role of HDL in the modulation of IS in acute metabolic stress conditions such as MI remains unknown. OBJECTIVE: To explore the association between plasma HDL-C and the change in IS during the acute phase of MI. METHODS: Consecutive nondiabetic patients with ST-segment elevation MI (n = 22) underwent direct measurement of IS through the euglycemic hyperinsulinemic clamp on the first morning and on the fifth day after onset of MI. Patients were grouped according to HDL-C levels at admission above and below the median value (35 mg/dL). RESULTS: At admission, there was no significant difference in baseline IS index, clinical, anthropometric, or treatment characteristics between low and high HDL groups. Between admission and fifth day, there was a decrease of 8% in IS index in the low HDL group and an 11% increase in the high HDL group (P = .001 for intragroup and P = .012 for intergroup difference). This difference remained significant after we controlled for the sex, age, waist circumference, triglycerides, baseline IS index, and statin dose during hospitalization. CONCLUSION: This is the first study to provide evidence that plasma levels of HDL-C are strongly associated with the recovery rate of IS during the acute phase of MI.

High sodium intake adversely affects oxidative-inflammatory response, cardiac remodelling and mortality after myocardial infarction.

OBJECTIVE: Enhanced sodium intake increases volume overload, oxidative stress and production of proinflammatory cytokines. In animal models, increased sodium intake favours ventricular dysfunction after myocardial infarction (MI). The aim of this study was to investigate, in human subjects presenting with ST-segment elevation MI (STEMI), the impact of sodium intake prior the coronary event. METHODS: Consecutive patients (n=372) admitted within the first 24 h of STEMI were classified by a food intake questionnaire as having a chronic daily intake of sodium higher (HS) or lower (LS) than 1.2 g in the last 90 days before MI. Plasma levels of 8-isoprostane, interleucin-2 (IL-2), tumour necrosis factor type α (TNF-α), C-reactive protein (CRP) and brain natriuretic peptide (BNP) were measured at admission and at the fifth day. Magnetic resonance imaging was performed immediately after discharge. Total mortality and recurrence of acute coronary events were investigated over 4 years of follow-up. RESULTS: The decrease of 8-isoprostane was more prominent and the increase of IL-2, TNF-α and CRP less intense during the first 5 days in LS than in HS patients (p<0.05). Sodium intake correlated with change in plasma BNP between admission and fifth day (r=0.46; p<0.0001). End-diastolic volumes of left atrium and left ventricle were greater in HS than in LS patients (p<0.05). In the first 30 days after MI and up to 4 years afterwards, total mortality was higher in HS than in LS patients (p<0.05). CONCLUSION: Excessive sodium intake increases oxidative stress, inflammatory response, myocardial stretching and dilatation, and short and long-term mortality after STEMI.