Insulin resistance and hyperlipoproteinemia in microvascular angina: risk factors or pathogenetic link?

BACKGROUNDPatients with chest pain and normal epicardial coronary arteries (micravascular angina; syndrome X) are characterized by an impairment of myocardial perfusion reserve which may be related to functional and morphological abnormalities of the intramyocardial arterioles. METHODSIn an attempt to identify predisposing factors for microvascular angina we investigated 34 consecutive patients (15 female, 19 male; mean age 53±7 years) with microvascular angina but without hypertension or left ventricular hypertrophy. The metabolic profile, including plasma insulin, glucose, cholesterol, low-density lipoprotein cholesterol, triglycerides, very-low-density lipoprotein cholesterol and fibrinogen levels, was determined in each case. Furthermore, insulin and glucose levels were measured after an oral glucose load of 100g over 3h. All parameters were compared with those of a control group of 15 healthy subjects matched for age, sex and body mass index. RESULTSThe systolic blood pressure in microvascular angina was 137±17mmHg and thus higher than that of healthy controls (124± 11 mmHg); diastolic blood pressure was 85±7 compared with 78±9 mmHg in controls. Insulin level was significantly elevated in patients with microvascular angina 90min (median101 versus 54 μU/ml) and 120min (median88 versus 51 μU/ml) after ingestion of 100g glucose. The fasting glucose level was 98±12 versus 87±7mg/dl in controls. Glucose concentration was also elevated after 30 min (176±28 versus 148±32mg/dl), after 45min (198±35 versus 152±53mg/dl) and after 60min (193±44 versus 145± 54 mg/dl). In microvascular angina, parameters such as total cholesterol (244 ± 46 versus 199±29mg/dl), low-density lipoprotein cholesterol (157±41 versus 122±18 mg/dl) and fibrinogen (377±150 versus 285±69 mg/dl) were elevated. CONCLUSIONSThe metabolic profile in patients with microvascular angina suggests a pathogenetic role of insulin resistance and hyperlipoproteinemia in the setting of impaired myocardial coronary reserve and in early stages of hypertensive heart disease.