Pharmacologic considerations in the positioning of β-blockers in antihypertensive therapy

Perspective Review: Type 2 Diabetes and Readmission for Heart Failure

Heart failure is a leading cause for hospitalisation and for readmission, especially in patients over the age of 65. Diabetes is an increasingly common companion to heart failure. The presence of diabetes and its associated comorbidity increases the risk of adverse outcomes and premature mortality in patients with heart failure. In particular, patients with diabetes are more likely to be readmitted to hospital soon after discharge. This may partly reflect the greater severity of heart disease in these patients. In addition, agents that reduce the chances of readmission such as β-blockers, renin-angiotensin-aldosterone system blockers, and mineralocorticoid receptor antagonists are underutilised because of the perceived increased risks of adverse drug reactions and other limitations. In some cases, readmission to hospital is precipitated by acute decompensation of heart failure (re-exacerbation) leading to pulmonary congestion and/or refractory oedema. However, it appears that for most of the patients admitted and then discharged with a primary diagnosis of heart failure, most readmissions are not due to heart failure, but rather due to comorbidity including arrhythmia, infection, adverse drug reactions, and renal impairment/reduced hydration. All of these are more common in patients who also have diabetes, and all may be partly preventable. The many different reasons for readmission underline the critical value of multidisciplinary comprehensive care in patients admitted with heart failure, especially those with diabetes. A number of new strategies are also being developed to address this area of need, including the use of SGLT2 inhibitors, novel nonsteroidal mineralocorticoid antagonists, and neprilysin inhibitors.

Type 2 Diabetes and Heart Failure: Challenges and Solutions

Increasing numbers of older patients with type 2 diabetes, and their improved survival from cardiovascular events is seeing a massive increase in patients with both diabetes and heart failure. Already, at least a third of all patients with heart failure have diabetes. This close association is partly because all the major risk factors for heart failure also cluster in patients with type 2 diabetes, including obesity, hypertension, advanced age, sleep apnoea, dyslipidaemia, anaemia, chronic kidney disease, and coronary heart disease. However, diabetes may also cause cardiac dysfunction in the absence of overt macrovascular disease, as well as complicate the response to therapy. Current management is focused on targeting modifiable risk factors for heart failure including hyperglycaemia, dyslipidaemia, hypertension, obesity and anemia. But although these are important risk markers, none of these interventions substantially prevents heart failure or improves its outcomes. Much more needs to be done to focus on this issue, including the inclusion of hospital admission for heart failure as a pre-specified component of the primary composite cardiovascular outcomes and new trials in heart failure management specifically in the context of diabetes.

The role and management of sympathetic overactivity in cardiovascular and renal complications of diabetes

Feedback activation of neurohormonal pathways in the setting of kidney or heart failure contributes to the development and progression of dysfunction in the other. Diabetes and its management independently activate these same pathogenic pathways, feeding into this vicious cycle and contributing to a poor prognosis. One of the most important of these neurohormonal pathways is the sympathetic nervous system (SNS). The activity of the SNS in increased in patients with chronic kidney disease, even in the absence of renal impairment or heart failure. There is a strong relationship between SNS overactivity and prognosis, and evidence that blockade of SNS reduces morbidity and mortality in patients with diabetes. However, modulation of SNS is underutilised as a strategy to protect both the diabetic kidney and the heart. This is partly because of the historically poor tolerability, adverse haemodynamic and metabolic effects, lack of selectivity of β-blockers and the lack of specificity of other interventions that might modify SNS activation. The advent of "vasodilating β-blockers" with better tolerability as well as more favourable effects on renal function and metabolic profiles opens the door for their more widespread utility in patients with diabetes. Radiofrequency renal sympathectomy and baroreflex activation technologies also offer exciting new ways to tackle the challenge of sympathetic overactivity.

Realities of newer beta-blockers for the management of hypertension

Beta-blockers are prescribed for a variety of cardiovascular conditions including hypertension, heart failure, primary treatment of myocardial infarction (MI), and secondary prevention of ischemic cardiac events. Yet they remain underprescribed in populations at increased risk for cardiovascular disease because of tolerability and safety concerns. Beta-blockers are heterogeneous with respect to pharmacokinetic and pharmacodynamic effects. "Original" agents were nonselective, blocking both beta1-adrenoceptors and beta2-adrenoceptors. Later, new agents were developed with selectivity for beta1-adrenoceptors, and were subsequently followed by beta-blockers, which exhibit additional effects, such as vasodilation. Among newer agents, labetalol, carvedilol, and nebivolol have been approved for use in the United States. Nebivolol possesses both beta1-selectivity and nitric oxide-mediated vasodilatory effects, while carvedilol has attractive effects on insulin resistance and exhibits antioxidant effects. Newer beta-blockers may overcome concerns about efficacy, adverse effects, and tolerability, while delivering cardiovascular protection.