Clinical and echocardiographic parameters as risk factors for atrial fibrillation in patients with hypertrophic cardiomyopathy.

BACKGROUND: Atrial fibrillation (AF) is a common complication in patients with hypertrophic cardiomyopathy (HCM) and may contribute to high cardiovascular morbidity and mortality. Therefore, it is important to assess parameters associated with AF in HCM patients. HYPOTHESIS: The aim of the study was to evaluate AF prevalence in patients with HCM and to investigate risk factors for AF. METHODS: Five hundred and forty-six HCM patients aged below 65 were included into analysis. Clinical and echocardiographic parameters were analyzed. RESULTS: In 141 patients (25.8%) AF episodes were recorded. The following factors were identified as risk factors for AF in patients with HCM: age ≥ 45 years (OR 2.38, CI 1.40-4.05, P = 0.001), past history of presyncope or syncope (OR 2.25, CI 1.35-3.74, P = 0.002), non-sustained ventricular tachycardia (nsVT) (OR 2.70, CI 1.60-4.57, P < 0.001), left atrium diameter during first assessment (OR 1.065, CI 1.03-1.11, P = 0.001), left atrium diameter at the last assessment before AF occurrence (OR 1.10, CI 1.06-1.14, P < 0.001) and left ventricular ejection fraction at the last assessment before AF occurrence (CI 0.96, CI 0.94-0.98, P = 0.001). CONCLUSIONS: We confirm that AF is a common complication for patients with HCM. Identification of patients with high risk for AF and implementation of preventive strategies may reduce AF occurrence and its complications.

Influence of Diabetes Mellitus on Outcomes in Patients After Left Ventricular Assist Device Implantation.

BACKGROUND: Despite previous studies, the mortality risk of patients with diabetes mellitus after left ventricular assist device (LVAD) implant remains unclear. In addition, the relationship between the degree of glycemic control and long-term mortality risk in LVAD patients with diabetes has not been established. METHODS: Ninety-five nondiabetic patients and 96 diabetic patients from the University of Rochester Medical Center who received a HeartMate II (Thoratec, Pleasanton, CA) continuous-flow LVAD between May 2008 and June 2014 were included in this study. The primary outcome was all-cause mortality. Secondary outcomes included rates of infection, neurologic dysfunction, renal dysfunction, and rehospitalization. Kaplan-Meier survival analyses and Cox models were utilized. RESULTS: During follow-up, 32 diabetic patients (33%) and 15 nondiabetic patients (16%) died after LVAD implantation. Cumulative probability of death was higher for diabetic patients when compared with nondiabetic patients (42% versus 21% at 3 years, p = 0.013). There were no significant differences in overall rates of infection, neurologic dysfunction, and rehospitalization between the two groups. However, after an initial secondary outcome event, diabetic patients continued to have a higher mortality rate when compared with nondiabetic patients. There was no statistically significant difference in the risk of death between diabetic patients with pre-LVAD hemoglobin A1c less than 7.0% and diabetic patients with pre-LVAD hemoglobin A1c 7.0% or greater (hazard ratio 1.71, 95% confidence interval: 0.72 to 4.08, p = 0.223). CONCLUSIONS: Diabetic patients who underwent LVAD implantation had a higher risk of death compared with nondiabetic patients. Adverse event rates did not differ between the two groups. Finally, the degree of glycemic control in diabetic patients before LVAD was not found to influence mortality.

Risk of Cardiac Events Associated With Antidepressant Therapy in Patients With Long QT Syndrome.

Patients with long QT syndrome (LQTS) are at a high risk of cardiac events. Many patients with LQTS are treated with antidepressant drugs (ADs). We investigated the LQTS genotype-specific risk of recurrent cardiac arrhythmic events (CAEs) associated with AD therapy. The study included 59 LQT1 and 72 LQT2 patients from the Rochester-based LQTS Registry with corrected QT (QTc) prolongation and a history of AD therapy. Using multivariate Anderson-Gill models, we estimated the LQTS genotype-specific risk of recurrent CAEs (ventricular tachyarrhythmias, aborted cardiac arrest, or sudden cardiac death) associated with time-dependent ADs. Specifically, we examined the risk associated with all ADs, selective serotonin reuptake inhibitor (SSRI), and ADs classified on the CredibleMeds list (www.CredibleMeds.org) as "Conditional" or "Known risk of Torsades de pointes (TdP)." After adjusting for baseline QTc duration, sex, and time-dependent beta-blocker usage, there was an increased risk of recurrent CAEs associated with ADs in LQT1 patients (hazard ratio = 3.67, 95% confidence interval 1.98-6.82, p < 0.001) but not in LQT2 patients (hazard ratio = 0.89, 95% confidence interval 0.49-1.64, p = 0.716; LQT1 vs LQT2 interaction, p < 0.001). Similarly, LQT1 patients who were on SSRIs or ADs with "Known risk of TdP" had a higher risk of recurrent CAEs than those patients off all ADs, whereas there was no association in LQT2 patients. ADs with "Conditional risk of TdP" were not associated with the risk of recurrent CAEs in any of the groups. In conclusion, the risk of recurrent CAEs associated with time-dependent ADs is higher in LQT1 patients but not in LQT2 patients. Results suggest a LQTS genotype-specific effect of ADs on the risk of arrhythmic events.

Pharmacologic Conversion during Dofetilide Treatment for Persistent Atrial Fibrillation.

BACKGROUND: Dofetilide is a pure IKr blocker and is one of the few drugs specifically studied and approved in the United States for the management of persistent atrial fibrillation (AF). Dofetilide has been noted to have a high rate of pharmacologic conversion during initial dosing in prior smaller studies. The intent of the study was to examine the safety of an inpatient loading strategy, and the incidence and patterns of pharmacologic conversion by dofetilide during the treatment of persistent AF in a large consecutive cohort. METHODS AND RESULTS: This is a retrospective analysis of 308 consecutive patients with persistent AF electively admitted for inpatient dofetilide loading. The initiation dose of dofetilide was determined by the creatinine clearance. Overall, 88% (n = 271) successfully completed initiation of dofetilide and were discharged in sinus rhythm. The most common reason for failure to complete initiation of dofetilide loading was QTc prolongation in 24 patients (7.8%), and torsade de pointes occurred in three patients (1%). Pharmacologic conversion was observed in 56% (n = 151) after a median of two doses. The rate of pharmacologic conversion based on the final dose was 75%, 9%, and 0% for 500 mcg, 250 mcg, and 125 mcg, respectively (P < 0.05). CONCLUSIONS: Dofetilide is a well-tolerated antiarrhythmic drug with a low incidence of proarrhythmia and an especially high rate of pharmacologic conversion in patients with persistent AF.

Evaluation of the counter-regulatory responses to hypoglycaemia in patients with type 1 diabetes during opiate receptor blockade with naltrexone.

AIMS: Hypoglycaemia is the major limiting factor in achieving optimal glycaemic control in people with type 1 diabetes (T1DM), especially intensively treated patients with impaired glucose counter-regulation during hypoglycaemia. Naloxone, an opiate receptor blocker, has been reported to enhance the acute counter-regulatory response to hypoglycaemia when administered intravenously in humans. The current study was undertaken to investigate the oral formulation of the long-acting opiate antagonist, naltrexone, and determine if it could have a similar effect, and thus might be useful therapeutically in treatment of T1DM patients with a high risk of hypoglycaemia. MATERIALS AND METHODS: We performed a randomized, placebo-controlled, double-blinded, cross-over study in which 9 intensively treated subjects with T1DM underwent a 2-step euglycaemic-hypoglycaemic-hyperinsulinaemic clamp on 2 separate occasions. At 12 hours and at 1 hour before the clamp study, participants received 100 mg of naltrexone or placebo orally. Counter-regulatory hormonal responses were assessed at baseline and during each step of the hyperinsulinaemic-clamp. RESULTS: Glucose and insulin levels did not differ significantly between the naltrexone and placebo visits; nor did the glucose infusion rates required to keep glucose levels at target. During hypoglycaemia, naltrexone, in comparison with the placebo group, induced an increase in epinephrine levels ( P = .05). However, no statistically significant differences in glucagon, cortisol and growth hormone responses were observed. CONCLUSION: In contrast to the intravenous opiate receptor blocker naloxone, overnight administration of the oral long-acting opiate receptor blocker, naltrexone, at a clinically used dose, had a limited effect on the counter-regulatory response to hypoglycaemia in intensively treated subjects with T1DM.

Validation of an automatic diagnosis of strict left bundle branch block criteria using 12-lead electrocardiograms.

AIMS: Strict left bundle branch block (LBBB) criteria were recently proposed to identify LBBB patients to benefit most from cardiac resynchronization therapy (CRT). The aim of our study was to automate identification of strict LBBB in order to facilitate its broader application. METHODS: We developed a series of algorithms to automatically detect and measure parameters required for strict LBBB criteria and proposed a definition of QRS notch detection. The algorithms were developed using training (n = 20) and validation (n = 592) sets consisting of signal-averaged 12-lead ECGs (1,000 Hz sampling) recorded from 612 LBBB patients from Multicenter Automatic Defibrillator Implantation Trial-CRT. Four trained clinicians independently performed adjudication on 148 different ECGs for comparing automatic and manually adjudicated results, in addition to 13 ECGs for evaluation of intraobserver variability and 32 ECGs for interobserver variability. We assessed the performance of the automated algorithms using manually adjudicated ECGs as references. RESULTS: Overall sensitivity and specificity for detecting strict LBBB were 95% and 86%, respectively. The mean absolute deviation (MAD) of QRS duration and notch/slur locations for the automated method versus the manual method was below 1 ms, and MAD values were lower than 2 ms for interobserver and intraobserver variability. Sensitivity and specificity for detecting notch and slur locations were 87% and 96% for notches and 78% and 90% for slurs using the automatic method. In addition 95% and 93% agreements for notches and 90% and 88% agreements for slurs were reached for intra- and interobserver. CONCLUSION: The proposed algorithms automatically measure QRS features for the diagnosis of strict LBBB. Our study shows good performance in reference to manual results.

Effect of Significant Weight Change on Inappropriate Implantable Cardioverter-Defibrillator Therapy.

BACKGROUND: Weight loss has been associated with adverse outcomes among heart failure (HF) patients, including those receiving cardiac resynchronization therapy with defibrillator (CRT-D). The effect of significant weight change on inappropriate implantable cardioverter-defibrillator (ICD) therapy among CRT-D patients is not well understood. METHODS: We evaluated the impact of significant weight change at 1 year on subsequent inappropriate ICD therapy during follow-up among 993 CRT-D patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy. Patients were divided into three subgroups based on weight change at 1 year after enrollment: weight loss (weight loss ≥ 5%), weight gain (weight gain ≥ 5%), and stable weight (weight loss and weight gain < 5%). The primary end point was inappropriate ICD therapy. Secondary end point included inappropriate ICD therapy related to supraventricular arrhythmias (SVAs). RESULTS: There were 102 (10.3%) patients who experienced weight loss, 689 (69.4%) whose weight was stable, and 202 (20.3%) who gained weight at 1 year. Patients with weight loss had increased risk of subsequent inappropriate ICD therapy relative to patients with stable weight (hazard ratio [HR] = 2.35, 95% confidence interval [CI]: 1.39-3.98, P = 0.001) or weight gain (HR = 2.27, 95% CI: 1.18-4.38, P = 0.014). Furthermore, patients losing weight were at greater risk of subsequent inappropriate ICD therapy related to SVAs when compared to patients with stable weight (HR = 2.16, 95% CI: 1.18-3.95, P = 0.013) or weight gain (HR = 2.02, 95% CI: 0.95-4.29, P = 0.068). CONCLUSION: In mild HF patients receiving CRT-D, significant weight loss at 1 year is associated with increased risk of subsequent inappropriate ICD therapy, including risk related to SVAs.

Effect of obesity on the effectiveness of cardiac resynchronization to reduce the risk of first and recurrent ventricular tachyarrhythmia events.

BACKGROUND: Obesity is associated with multiple adverse cardiovascular conditions and may increase the risk of ventricular tachyarrhythmias (VT/VF). There is limited data on the association between obesity and risk of VT/VF requiring appropriate implantable cardioverter-defibrillator (ICD) therapies and the effectiveness of cardiac resynchronization therapy (CRT) to reduce risk for VT/VF. The multicenter automatic defibrillator implantation trial with cardiac resynchronization therapy (MADIT-CRT) was design to investigate effectiveness of CRT therapy to reduce cardiovascular outcome for patients with heart failure (HF) and reduced ejection fraction. METHODS AND RESULTS: We identified patients enrolled in the MADIT CRT trial as obese (n = 433) and non-obese (n = 845) and analyzed their risk for appropriate device therapy for VT/VF, repeated VT/VF events, fast VT/VF, as well as events after first VT/VF episodes. Obesity was defined as body mass index (BMI) ≥30 kg/m(2). Among ICD patients, the risk of first appropriate ICD therapy for VT/VF at 3 years was similar between obese and non-obese patients (23 vs. 21 %, p = 0.76). CRT-D treatment reduced the risk of first appropriate ICD therapy both in non-obese ([HR]; 0.58 [CI]: 0.42-0.79; p < 0.001) and obese patients (HR 0.75, 95 % CI 0.5-1.38; p = 0.179) (interaction p value 0.323). Similarly, a significant reduction in the risk of fast VT/VF was observed in non-obese patients ([HR]; 0.49 [CI]: 0.33-0.73; p < 0.001) and obese ([HR]; 0.49 [CI]: 0.29-0.81; p < 0.01), (interaction p value 0.984). CONCLUSION: Obese and non-obese patients with mild heart failure have a similar risk of ventricular tachyarrhythmias. Obesity in mild heart failure did not diminish the clinical benefit of cardiac resynchronization therapy to reduce risk for appropriate ICD therapy. Clinical trial registration http://clinicaltrials.gov/ct2/show/NCT00180271.

Metabolic syndrome is associated with different clinical outcome after cardiac resynchronization therapy in patients with ischemic and non-ischemic cardiomyopathy.

BACKGROUND: Although association of metabolic syndrome (MS) and ischemic heart disease is strongly established, it is not known whether presence of MS may differently influence clinical responses to cardiac resynchronization therapy (CRT). The aim of this study was to evaluate the associations between obesity and metabolic features and the clinical outcome after cardiac resynchronization with defibrillator therapy (CRT-D), compared to an implantable cardioverter defibrillator (ICD). METHODS: The risk of heart failure (HF) or death and death alone was evaluated in 829 non-obese patients, 156 obese patients without MS, and 277 obese patients with MS (all with left bundle branch block), who were enrolled in the Multicenter Automatic Defibrillator Implanta-tion Trial with Cardiac Resynchronization Therapy (MADIT-CRT). RESULTS: Obese patients with MS (HR 0.50, 95% CI 0.32-0.77, p = 0.002), obese patients without MS (HR 0.57, 95% CI 0.30-1.06, p = 0.077), and non-obese patients (HR 0.48, 95% CI 0.37-0.62, p < 0.001) had a similar risk reduction of HF/death in response to CRT-D therapy when compared to ICD patients. However, among those with non-ischemic cardiomyo-pathy, obese patients with MS experienced a 90% reduction for HF/death (HR 0.11, 95% CI 0.04-0.32, p < 0.001), whereas obese patients without MS had no reduction (HR 0.98, 95% CI 0.48-1.98, p = 0.951; interaction p < 0.001). The reverse was observed in ischemic car-diomyopathy patients: obese patients with MS had no reduction in the risk of HF/death (HR 0.80, 95% CI 0.48-1.34, p = 0.402), while obese patients without MS showed a significant reduction in the risk of events (HR 0.15, 95% CI 0.04-0.65, p = 0.011; interaction p = 0.036). Similar trends were observed for the endpoint of death. CONCLUSIONS: Presence of MS differentiates the response to CRT in obese patients with is-chemic and non-ischemic etiology for HF.

Endocrine autoimmunity in patients with Latent Autoimmune Diabetes in Adults (LADA) ­ association with HLA genotype.

INTRODUCTION: Latent autoimmune diabetes in adults (LADA) is a slow-developing form of autoimmune diabetes, characterised by the presence of type 1 diabetes-associated autoantibody and presentation at diagnosis similar to patients with type 2 diabetes. The aim of this study was to determine the prevalence of auto-antibodies related to endocrine autoimmune diseases in patients with LADA and to assess their association with HLA genotype. MATERIAL AND METHODS: We evaluated the presence of anti-thyroglobulin (ATG), anti-thyroid peroxidase (ATPO), anti-tissue transglutaminase IgA (ATTA), and anti 21 hydroxylase (A21H) in 70 patients with LADA, 69 with Type 2 diabetes, and in 50 healthy controls HLA genotype was assed in subpopulation of sluclied subjects. RESULTS: The presence of ATPO (28.6 vs. 10%); ATG (28.6 vs. 14%) was higher in patients with LADA in comparison to healthy controls and ATPO in comparison to patients with type 2 diabetes (38.6 vs. 17.4 %). In patients with LADA the presence of autoimmune thyroid autoantibodies was associated with newly diagnosed subclinical hypothyroidism; almost 7% of patients presented with high TSH. The presence of A21H (2.86 vs. 5.8 vs. 6.1%) and ATTA (2.86 vs. 4.3 vs. 6.0%) was not different between groups. Patients with high TSH level were positive for DQA1*0301 and DRB1*04 HLA genotype: DQB1*0201 and DQB1*02 were higher in patients positive for ATTA. CONCLUSIONS: Patients with LADA have higher prevalence of thyroid autoimmune diseases. In patients with LADA similarly to type 1 genotype DQA1*0301 seems to CONFER susceptibility to thyroid autoimmunity, and DQB1*0201 to celiac disease.

Relative Wall Thickness and the Risk for Ventricular Tachyarrhythmias in Patients With Left Ventricular Dysfunction.

BACKGROUND: Relative wall thickness (RWT), defined as 2 times posterior wall thickness divided by the left ventricular (LV) diastolic diameter, is a measure of LV geometry and may be a marker for adverse events in patients with LV dysfunction. OBJECTIVES: The aim of this study was to investigate the relationship between RWT and the risk for ventricular tachyarrhythmia (VA) in patients enrolled in the MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy) study. METHODS: The study population comprised 1,260 patients with mild heart failure and left bundle branch block. RESULTS: In a multivariable model, RWT was the most powerful echocardiographic measure for estimating the risk of VAs compared with commonly used echocardiographic variables. Patients with low RWT (<0.24) had 83% (p < 0.001) increased risk for VA and 68% (p < 0.001) increase in VA risk or death (VA/death) compared with patients with higher RWT values. Each 0.01-unit decrease in RWT was associated with 12% (p < 0.001) and 10% (p < 0.001) increases in the risk of VA and VA/death, respectively. Treatment with cardiac resynchronization therapy with defibrillator (CRT-D; CRT with implantable cardioverter-defibrillator) was associated with a greater increase in RWT compared with implantable cardioverter-defibrillator at 12 months (4.6 ± 6.8% vs. 1.5 ± 2.7%; p < 0.001), and every 10% increase in RWT in CRT-D patients was associated with 34% (p = 0.027) and 36% (p = 0.009) reductions in the risk of subsequent VA and VA/death, respectively. CONCLUSIONS: In patients with mild heart failure and left bundle branch block, decreased RWT was associated with an increase in the risk of VA and VA/death. CRT-D therapy was associated with a favorable increase in RWT and reduction in risk of VA and VA/death. (Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy [MADIT-CRT]; NCT00180271).

Effects of Statins on First and Recurrent Supraventricular Arrhythmias in Patients With Mild Heart Failure (from the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy).

Previous studies suggested that statin therapy reduces the risk of occurrence and recurrence of atrial fibrillation mainly in patients with coronary artery disease. Data regarding the effect of statins on the risk for the entire range of supraventricular arrhythmias (SVA) in mild heart failure (HF) with different disease causes are lacking. Multivariate Cox proportional hazards regression models were used to assess the effect of statin therapy, evaluated as a time-dependent covariate, on the risk of SVA and recurrent SVA (defined as atrial fibrillation, atrial flutter, atrial tachycardia, and supraventricular tachycardia) that were inappropriately treated with implantable cardioverter-defibrillator device in 1,790 patients enrolled in the Multicenter Automatic Defibrillator Implantation With Cardiac Resynchronization Therapy trial. Statin users constituted 68% of the study patients (n = 1209). They were older and more frequently men; they were more likely to have ischemic cardiomyopathy, diabetes, hypertension, and previous atrial arrhythmias. During the 3.7-year median follow-up time, 160 patients had an SVA event, and the total number of recurrent events was 335. Time-dependent statin therapy was independently associated with a significant 29% reduction of the first SVA event (p = 0.046) and 33% reduction of recurrent SVA events (p = 0.003), consistent across all prespecified subgroups. In conclusion, in mild HF with either cardiac resynchronization therapy with a defibrillator or an implantable cardioverter-defibrillator device, statin therapy was associated with significant reduction of occurrence and recurrence of inappropriately treated SVA.

Inhaled Formoterol Diminishes Insulin-Induced Hypoglycemia in Type 1 Diabetes.

OBJECTIVE: Hypoglycemia is one of the major factors limiting implementation of tight glycemic control in patients with type 1 diabetes and is associated with increased morbidity and mortality during intensive insulin treatment. ß-2 Adrenergic receptor (AR) agonists have been reported to diminish nocturnal hypoglycemia; however, whether long-acting inhaled ß-2 AR agonists could potentially be used to treat or prevent hypoglycemia has not been established. RESEARCH DESIGN AND METHODS: Seven patients with type 1 diabetes and seven healthy control subjects received inhaled formoterol (48 µg), a highly specific ß-2 AR agonist, or a placebo during a hyperinsulinemic-hypoglycemic clamp study to evaluate its capacity to antagonize the effect of insulin. In a second set of studies, five subjects with type 1 diabetes received inhaled formoterol to assess its effect as a preventive therapy for insulin-induced hypoglycemia. RESULTS: During a hyperinsulinemic-hypoglycemic clamp, compared with placebo, inhaled formoterol decreased the glucose infusion rate required to maintain plasma glucose at a target level by 45-50% (P < 0.05). There was no significant effect on glucagon, epinephrine, cortisol, or growth hormone release (P = NS). Furthermore, in volunteers with type 1 diabetes 1 h after increasing basal insulin delivery twofold, glucose levels dropped to 58 ± 5 mg/dL, whereas hypoglycemia was prevented by inhaled formoterol (P < 0.001). CONCLUSIONS: Inhalation of the ß-2 AR-specific agonist formoterol may be useful in the prevention or treatment of acute hypoglycemia and thus may help patients with type 1 diabetes achieve optimal glucose control more safely.

Effect of Cardiac Resynchronization Therapy in Patients With Insulin-Treated Diabetes Mellitus.

Diabetes mellitus (DM) modify outcome in patients with heart failure (HF). We aimed to analyze the risk for death, HF alone, combined end point HF/death, and ventricular tachycardia/ventricular fibrillation (VT/VF) in patients with mild HF without DM and in those with DM, further stratified by the presence of insulin treatment. We determined whether cardiac resynchronization therapy with defibrillator (CRT-D) versus implantable cardioverter defibrillator improves clinical outcomes in these 3 subgroups. Cox proportional hazards regression models were used to analyze 1,278 patients with left bundle branch block in the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy trial. Treatment with CRT-D versus implantable cardioverter defibrillator was associated with 76% risk reduction in all-cause mortality (hazard ratio 0.24; 95% confidence interval 0.08 to 0.74, p = 0.012) in subgroup of diabetic patients treated with insulin only (interaction p = 0.043). Significant risk reduction in HF alone, HF/death, and the VT/VF after CRT-D was observed across investigated groups and similar left ventricular reverse remodeling to CRT-D. In conclusion, patients with mild HF with DM treated with insulin derive significant risk reduction in mortality, in HF, and VT/VF after implantation of CRT-D. Diabetic patients not receiving insulin benefit from CRT-D by reduction of HF events.

Insulin resistance predicts the risk for recurrent coronary events in post-infarction patients.

BACKGROUND: We investigated the risk for recurrent coronary events associated with insulin resistance in post-infarction patients from the Thrombogenic Factors and Recurrent Coronary Events (THROMBO) study. METHODS: The association between insulin resistance expressed by Homeostatic Model As-sessment 2 for Insulin Resistance (HOMA2-IR) and the risk for recurrent coronary events was investigated in a cohort of 1,032 patients evaluated 2 months after myocardial infarction (MI) with a follow-up of 26 months. The endpoint for the study was recurrent coronary event defined as cardiac death, nonfatal MI, or unstable angina, whichever occurred first. We used time dependent survival analysis and Cox proportional hazards regression method to determine the association between HOMA2 categorized as high > 75th percentile and endpoints after adjustment for relevant clinical covariates and series of thrombogenic and dyslipogenic factors. RESULTS: High HOMA2-IR defined as in fourth quartile (≥ 2.4) was associated with increased risk for recurrent coronary events (HR 1.44; CI 1.03-2.01; p = 0.03) after adjustment for the clinical covariates: age, gender, diabetes, prior MI, pulmonary congestion, coronary artery bypass grafting and percutaneous transluminal coronary angioplasty. The highest risk of cardiac events was observed in non-obese patients (body mass index [BMI] ≤ 30 kg/m2) with high HOMA2-IR (HR 1.5; CI 1.02-2.22; p = 0.038). The plasma level of plasminogen activa-tor inhibitor-1 was associated with higher risk for recurrent coronary events in patients with insulin resistance (HR 1.79; CI 1.05-3.03; p = 0.03, interaction p = 0.018). CONCLUSIONS: In conclusion, insulin resistance predicts recurrence of coronary events in post-infarction population. HOMA2-IR is better than BMI in stratifying risk of recurrent coronary events.

Role of synaptic plasticity and EphA5-ephrinA5 interaction within the ventromedial hypothalamus in response to recurrent hypoglycemia.

Hypoglycemia stimulates counterregulatory hormone release to restore euglycemia. This protective response is diminished by recurrent hypoglycemia, limiting the benefits of intensive insulin treatment in patients with diabetes. We previously reported that EphA5 receptor-ephrinA5 interactions within the ventromedial hypothalamus (VMH) influence counterregulatory hormone responses during acute hypoglycemia in nondiabetic rats. In this study, we examined whether recurrent hypoglycemia alters the capacity of the ephrinA5 ligand to activate VMH EphA5 receptors, and if so, whether these changes could contribute to pathogenesis of defective glucose counterregulation in response to a standard hypoglycemic stimulus. The expression of ephrinA5, but not EphA5 receptors within the VMH, was reduced by antecedent recurrent hypoglycemia. In addition, the number of synaptic connections was increased and astroglial synaptic coverage was reduced. Activation of VMH EphA5 receptors via targeted microinjection of ephrinA5-Fc before a hyperinsulinemic hypoglycemic clamp study caused a reduction in the glucose infusion rate in nondiabetic rats exposed to recurrent hypoglycemia. The increase in the counterregulatory response to insulin-induced hypoglycemia was associated with a 150% increase in glucagon release (P < 0.001). These data suggest that changes in ephrinA5/EphA5 interactions and synaptic plasticity within the VMH, a key glucose-sensing region in the brain, may contribute to the impairment in glucagon secretion and counterregulatory responses caused by recurrent hypoglycemia.

ß2-Adrenergic receptor agonist administration promotes counter-regulatory responses and recovery from hypoglycaemia in rats.

AIMS/HYPOTHESIS: We have previously reported that local activation of ß2-adrenergic receptors (B2ARs) in the ventromedial hypothalamus (VMH) enhances hypoglycaemic counter-regulation. This study examines whether peripheral delivery of a selective B2AR agonist could also promote counter-regulatory responses and thereby has potential therapeutic value to limit hypoglycaemia risk. METHODS: Conscious male Sprague-Dawley rats received an intra-arterial injection of the B2AR specific agonist, formoterol, or a control solution either before a hyperinsulinaemic-hypoglycaemic clamp study or immediately before recovery from insulin-induced hypoglycaemia. In addition, the capacity of a VMH-targeted microinjection of a B2AR antagonist to limit the anti-insulin effect of the B2AR agonist was assessed. RESULTS: Systemic delivery of B2AR agonist markedly reduced the exogenous glucose infusion rate (GIR) required during the hypoglycaemic clamp study. This effect was mediated by blockade of insulin's inhibitory effect on endogenous glucose production. Local blockade of B2ARs within the VMH using a specific antagonist partially diminished the effect of systemic activation of B2ARs during hypoglycaemia at least in part by diminishing the adrenaline (epinephrine) response to hypoglycaemia. Peripheral B2AR agonist injection also enhanced glucose recovery from insulin-induced hypoglycaemia. CONCLUSIONS/INTERPRETATION: Systemic B2AR agonist administration acts to limit insulin-induced hypoglycaemia by offsetting insulin's inhibitory effect on hepatic glucose production. This effect appears to be predominately mediated via a direct effect on liver B2ARs, but a small stimulatory effect on B2ARs within the VMH cannot be excluded. Our data suggest that formoterol may have therapeutic value to limit the risk of hypoglycaemia in patients with diabetes.

EphA5-EphrinA5 interactions within the ventromedial hypothalamus influence counterregulatory hormone release and local glutamine/glutamate balance during hypoglycemia.

Activation of ß-cell EphA5 receptors by its ligand ephrinA5 from adjacent ß-cells has been reported to decrease insulin secretion during hypoglycemia. Given the similarities between islet and ventromedial hypothalamus (VMH) glucose sensing, we tested the hypothesis that the EphA5/ephrinA5 system might function within the VMH during hypoglycemia to stimulate counterregulatory hormone release as well. Counterregulatory responses and glutamine/glutamate concentrations in the VMH were assessed during a hyperinsulinemic-hypoglycemic glucose clamp study in chronically catheterized awake male Sprague-Dawley rats that received an acute VMH microinjection of ephrinA5-Fc, chronic VMH knockdown, or overexpression of ephrinA5 using an adenoassociated viral construct. Local stimulation of VMH EphA5 receptors by ephrinA5-Fc or ephrinA5 overexpression increased, whereas knockdown of VMH ephrinA5 reduced counterregulatory responses during hypoglycemia. Overexpression of VMH ephrinA5 transiently increased local glutamate concentrations, whereas ephrinA5 knockdown produced profound suppression of VMH interstitial fluid glutamine concentrations in the basal state and during hypoglycemia. Changes in ephrinA5/EphA5 interactions within the VMH, a key brain glucose-sensing region, act in concert with islets to restore glucose homeostasis during acute hypoglycemia, and its effect on counterregulation may be mediated by changes in glutamate/glutamine cycling.