Diabetes and mortality in heart failure

Symposium: The burden of diabetes in heart disease in Europe, lessons of the EuroHeart Survey Programme. 751004 & 750002

Vienna, Austria, 2 September 2007:

Diabetes is becoming one of the major health problems in the European and US populations. It is frequently associated with overweight, hypertension and high serum cholesterol levels, representing a dangerous combination of risk factors for the development of heart and vascular diseases. Recent large surveys and registries in patients with heart failure, including the Euro Heart Failure Surveys (EHFS) I and II, have shown that diabetes in such patients was also present in 30-40 % of cases. Slightly more women than men were found to have this condition.

This additional metabolic disorder worsens long-term prognosis and complicates the management of patients with acute and chronic heart failure. Analysis of the EHFS II follow-up data documented for the first time an increased early and late mortality in acute heart failure in diabetic patients: At 3 month after hospitalisation for a cardiac decompensation diabetes was more frequent in patients who died (43.3%) than in survivors (32,1%).

A similar association of diabetes with an adverse outcome was found during the post-discharge period between 3 and 12 months (38.2% in non-survivors versus 30.8% in survivors). A multivariate statistical testing has identified diabetes as an independent risk factor contributing to a relative mortality increase of 26% at 1 year. A higher mortality was also observed in diabetic patients with chronic heart failure in the large scale betablocker trial comparing carvedilol and metoprolol (COMET). However, not all surveys in chronic heart failure recognised diabetes as an independent risk factor, probably because other negative prognostic features, such as a markedly reduced left ventricular ejection factor, low blood pressure and renal dysfunction had a greater impact on long term outcome.

The presence of diabetes also influences the selection of optimal therapeutic measures in heart failure. Among the modern cardiovascular drugs the angiotensin converting enzyme inhibitors (ACEI) and the angiotensin receptor antagonists (ARA) are the most suitable agents in such patients, since they do not increase blood glucose and reduce the occurrence of new diabetes when compared to diuretics and some betablockers. Furthermore, these drugs have also protective effects on the kidneys against diabetic complications.

The choice of invasive cardiac interventions to treat coronary artery disease in patients with and without heart failure may also depend on the presence or absence of diabetes. Coronary artery bypass in patients with multi-vessel coronary disease is considered to be preferable to catheter interventions with regard to long term outcome. The rate of restenosis after percutaneous coronary dilatation is higher in diabetics, although the use of modern drug eluting stents can reduce this risk.

It has been shown that a strict blood sugar control by insulin treatment reduces the rate of cardiovascular diseases in diabetes. Whether the achievement of lower blood sugar values and reduction of glycosilated haemoglobin levels by different means has always a beneficial effect in patients with established cardiovascular diseases remains a debated issue. Recently, some publications have shown that a new antidiatbetic drug, rosiglitazone, which is superior to older drugs in correcting blood sugar, causes fluid retention with signs of heart failure and may even have a negative long term impact by increasing the rate of myocardial infarction and of cardiovascular death. The mode of action of antidiabetic drugs could therefore also be practically relevant.

The most important future task to reduce the negative effects of diabetes in patients with heart failure and coronary artery disease will be the prevention of its development by weight reduction, physical exercise and early treatment of other metabolic risk factors, in particular high cholesterol levels with appropriate drugs.