Effect of diabetes mellitus and its treatment on ventricular arrhythmias complicating acute myocardial infarction

Sulfonylureas and the Risk of Ventricular Arrhythmias Among People with Type 2 Diabetes: A Systematic Review of Observational Studies

Previous studies have suggested an association between sulfonylureas and an increased risk of cardiovascular death among patients with type 2 diabetes. A potential mechanism involves sulfonylurea-induced ventricular arrhythmias (VAs). We conducted a systematic review of observational studies to determine whether the use of sulfonylureas, compared with the use of other antihyperglycemic drugs, is associated with the risk of VA (ventricular tachycardia, ventricular fibrillation, and premature ventricular complexes), cardiac arrest, and sudden cardiac death among patients with type 2 diabetes. Two independent reviewers searched MEDLINE, EMBASE, CINAHL Plus, CENTRAL, and ClinicalTrials.gov from inception to July 2021 for observational studies comparing sulfonylureas vs. other antihyperglycemic therapies or intraclass comparisons of sulfonylureas. Our systematic review included 17 studies (1,607,612 patients). Per Risk Of Bias In Non-randomized Studies of Interventions (ROBINS)-I, there were few high-quality studies (2 studies at moderate risk of bias; 4 at serious risk; and 11 at critical risk). All studies at a moderate or serious risk of bias reporting comparisons with other therapies were consistent with an increased risk of VA. Sulfonylureas were associated with a higher risk of arrhythmia vs. dipeptidyl peptidase-4 inhibitors (adjusted hazard ratio (aHR): 1.52, 95% confidence interval (CI): 1.27-1.80) and of VA vs. metformin (aHR: 1.52, 95% CI: 1.10-2.13). One moderate quality study reported inconsistent results for a composite of cardiac arrest/VA in analyses of US Medicaid claims and Optum claims data. Our systematic review suggests that, among higher-quality observational studies, sulfonylureas are associated with an increased risk of VA. However, we identified few methodologically rigorous studies, underscoring the need for additional real-world studies.

Isolated downregulation of HCN2 in ventricles of rats with streptozotocin-induced diabetic cardiomyopathy

BACKGROUND

In spite of disrupted repolarization of diabetic heart, some studies report less tendency of diabetic heart to develop ventricular arrhythmias suggesting effective compensatory mechanism. We hypothesized that myocardial alterations in HCN2 and HCN4 channels occur under hyperglycaemia.

METHODS

Diabetes was induced in rats using a single injection of streptozotocin (STZ; 55 mg/kg body weight, i.p.). Basal ECG was measured. Expression of mRNA for HCN channels, potassium channels and microRNA 1 and 133a were measured in ventricular tissues. Protein expression of HCN2 channel isoform was assessed in five different regions of the heart by western blotting. Differentiated H9c2 cell line was used to examine HCN channels expression under hyperglycaemia in vitro.

RESULTS

Six weeks after STZ administration, heart rate was reduced, QRS complex duration, QT interval and T-wave were prolonged in diabetic rats compared to controls. mRNA and protein expressions of HCN2 decreased exclusively in the ventricles of diabetic rats. HCN2 expression levels in atria of STZ rats and H9c2 cells treated with excess of glucose were not changed. MicroRNA levels were stable in STZ rat hearts. We found significantly decreased mRNA levels of several potassium channels participating in repolarization, namely Kcnd2 (Ito1), Kcnh2 (IKr), Kcnq1 (IKs) and Kcnj11 (IKATP).

CONCLUSIONS

This result together with downregulated HCN2 channels suggest that HCN channels might be an integral part of ventricular electric remodelling and might play a role in cardiac repolarization projected in altered arrhythmogenic profile of diabetic heart.

Review: Sulphonylureas and cardiovascular risk: facts and controversies

Cardiovascular complications are the principal cause of death in type 2 diabetes. The importance of glycaemic control in preventing cardiovascular complications has been demonstrated. However, some oral antidiabetic agents and especially some sulphonylureas (SU) have been accused of having a deleterious effect on cardiovascular risk. A retrospective analysis of the administrative database of Saskatchewan Health for 5,795 subjects, identified by their first-ever dispensation for an oral antidiabetic agent, suggests that a higher exposure to SUs was associated with increased mortality. Nevertheless, the effects of SUs on cardiac ATP-sensitive potassium channels in experimental studies vary between agents and studies, so that the clinical relevance of this phenomenon is unclear. Moreover, 11 years of follow-up of patients randomised to glibenclamide or chlorpropamide in the United Kingdom Prospective Diabetes Study demonstrated no adverse effects on a range of cardiovascular end points. Despite SU structural differences and differences in binding to cardiac SU receptors, the clinical evidence base does not support the selection of one sulphonylurea over another on the basis of ischaemic preconditioning, possibly because ischaemic preconditioning may be blunted or absent in diabetes. The main objective remains the prevention or delay of diabetic complications through improvement of glycaemic control together with other cardiovascular risk factors.

Impact of type of preadmission sulfonylureas on mortality and cardiovascular outcomes in diabetic patients with acute myocardial infarction

BACKGROUND

The impact of antidiabetic medications on clinical outcomes in patients developing acute myocardial infarction (MI) is controversial. We sought to determine whether in-hospital outcomes in patients who were on sulfonylureas (SUs) when they developed their MIs differed from that of diabetic patients not receiving SUs and whether clinical outcomes were related to the pancreatic cells specificity of SUs.

METHODS AND RESULTS

We analyzed the outcomes of the 1310 diabetic patients included in the nationwide French Registry of Acute ST-Elevation and Non-ST-Elevation Myocardial Infarction in 2005. Medications used before the acute episode were recorded. In-hospital complications were analyzed according to prior antidiabetic treatment. Mortality was lower in patients previously treated with SUs (3.9%) vs. those on other oral medications (6.4%), insulin (9.4%), or no medication (8.4%) (P = 0.014). Among SU-treated patients, in-hospital mortality was lower in patients receiving pancreatic cells-specific SUs (gliclazide or glimepiride) (2.7%), compared with glibenclamide (7.5%) (P = 0.019). Arrhythmias and ischemic complications were also less frequent in patients receiving gliclazide/glimepiride. The lower risk in patients receiving gliclazide/glimepiride vs. glibenclamide persisted after multivariate adjustment (odds ratio 0.15; 95% confidence interval 0.04-0.56) and in propensity score-matched cohorts.

CONCLUSION

In this nationwide registry of patients hospitalized for acute MI, no hazard was associated with the use of SUs before the acute episode. In addition, patients previously receiving gliclazide/glimepiride had improved in-hospital outcomes, compared with those on glibenclamide.

Sulfonylurea therapy is associated with increased NT-proBNP levels in the treatment of type 2 diabetes

BACKGROUND

We sought to determine N-terminal pro-Brain Natriuretic Peptide (NTproBNP) levels among a population of individuals with type 2 diabetes, and to correlate these levels with diabetes medications and patient demographics.

METHODS

We analyzed data from 506 patients with type 2 diabetes. We compared NT-proBNP levels of these patients with those from the general population. We also sought to determine whether patients' NT-proBNP levels were correlated with diabetes medications, age, gender, creatinine, hemoglobin A1C levels, BMI, blood pressure, and lipid levels.

RESULTS

Increasing doses of sulfonylureas were associated with increasing levels of NT-proBNP. However, patients on combined sulfonylurea and metformin therapy had lower NT-proBNP levels than those on sulfonylureas alone. Neither thiazolidinediones nor insulin were associated with NT-proBNP levels. The majority of patients with type 2 diabetes had similar NT-proBNP levels compared to a reference group from the general population. In no age category did NT-proBNP levels differ significantly between men and women. Levels of NT-proBNP were positively associated with age (p<0.0001), systolic blood pressure (p<0.01) and creatinine levels (p<0.0001), and negatively associated with diastolic blood pressure (p<0.001). Levels of NT-proBNP were not associated with A1C, BMI, triglycerides, and high density lipoprotein (p=NS).

CONCLUSIONS

Levels of NT-proBNP are associated with increasing sulfonylurea dosage, age, blood pressure, and creatinine levels. There is unlikely to be clinically significant differences in NT-proBNP levels between patients with type 2 diabetes and a normal population.