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Insulin resistance and hyperlipoproteinemia in microvascular angina: risk factors or pathogenetic link?
K Langes1, C A Nienaber, C Volk
1Division of Cardiology, University Hospital Eppendorf, Hamburg, Germany.
Insights
Patients with microvascular angina exhibit elevated insulin and glucose levels, alongside higher cholesterol and fibrinogen, suggesting insulin resistance and hyperlipoproteinemia contribute to impaired heart function.
Area of Science:
- Cardiology
- Metabolic Syndrome
- Vascular Biology
Background:
- Microvascular angina, characterized by chest pain and normal coronary arteries, involves impaired myocardial perfusion reserve.
- This impairment may stem from abnormalities in intramyocardial arterioles.
Purpose of the Study:
- To identify predisposing factors for microvascular angina.
- To investigate the metabolic profile of patients with microvascular angina.
Main Methods:
- Studied 34 patients with microvascular angina (without hypertension or LVH) and 15 healthy controls.
- Assessed metabolic profiles: plasma insulin, glucose, cholesterol, LDL cholesterol, triglycerides, VLDL cholesterol, and fibrinogen.
- Measured insulin and glucose levels over 3 hours after an oral glucose load.
Main Results:
- Microvascular angina patients had higher systolic and diastolic blood pressure than controls.
- Significantly elevated insulin levels were observed 90 and 120 minutes post-glucose load.
- Elevated fasting glucose, post-load glucose, total cholesterol, LDL cholesterol, and fibrinogen were found in patients.
Conclusions:
- The metabolic profile suggests insulin resistance and hyperlipoproteinemia play a role in microvascular angina.
- These factors may contribute to impaired myocardial coronary reserve and early hypertensive heart disease.
Background:
Patients with chest pain and normal epicardial coronary arteries (microvascular 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.
Methods:
In 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 100 g over 3 h. All parameters were compared with those of a control group of 15 healthy subjects matched for age, sex and body mass index.
Results:
The systolic blood pressure in microvascular angina was 137 +/- 17 mmHg 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 90 min (median: 101 versus 54 microU/ml) and 120 min (median: 88 versus 51 microU/ml) after ingestion of 100 g glucose. The fasting glucose level was 98 +/- 12 versus 87 +/- 7 mg/dl in controls. Glucose concentration was also elevated after 30 min (176 +/- 28 versus 148 +/- 32 mg/dl), after 45 min (198 +/- 35 versus 152 +/- 53 mg/dl) and after 60 min (193 +/- 44 versus 145 +/- 54 mg/dl). In microvascular angina, parameters such as total cholesterol (244 +/- 46 versus 199 +/- 29 mg/dl), low-density lipoprotein cholesterol (157 +/- 41 versus 122 +/- 18 mg/dl) and fibrinogen (377 +/- 150 versus 285 +/- 69 mg/dl) were elevated.
Conclusions:
The 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.