Dilated cardiomyopathy (DCM) is characterized by a metabolic shift from fat to carbohydrates and failure to increase myocardial glucose uptake in response to workload increments. The investigators aimed at verifying whether this pattern is influenced by the presence of abnormal glucose tolerance (AGT).

A catheter is advanced into the coronary sinus by fluoroscopy to withdraw venous blood. A unipolar pacing catheter is positioned into the right atrium. Arterial sampling is done from the femoral artery introducer catheter.

The study protocol consisted of 3 steps (Rest, Pacing and Recovery), during which timed blood samples are collected to measure plasma NEFA and glucose. After the instrumentation is completed, Rest arterio-venous sampling is performed at time -15 min and 0 min. After the 0 min, heart rate is increased by atrial pacing to 110 bpm for 3 minutes and to 130 bpm for 3 additional minutes and arterio-venous sampling is repeated at the end of each step (at time 3 and 6 min). Pacing is then stopped and at time 1, 5, 15 and 30 min into the Recovery period other pairs of arterial and venous samples are withdrawn.

Inclusion Criteria:

For patients with dilated cardiomyopathy:

• Myocardial left ventricular ejection fraction (LVEF) <40%
• left ventricular end-diastolic diameter (LVEDD) >56 mm

For patients without dilated cardiomyopathy:

• LVEF >50%
• LVEDD <56 mm.

Exclusion Criteria:

• NYHA class IV
• Atrial fibrillation
• Previous myocardial infarction
• Valvular heart disease
• Myocarditis
• Pericarditis
• Severe to moderate systemic arterial hypertension
• Fasting hyperglycaemia (>7.0 mmol/l)
• Treated diabetes, autoimmune diseases, neoplasia, kidney, liver or respiratory failure

Cardiology Department of the Institute of Clinical physiology