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[Angina pectoris with normal coronary arteries: clinical, hemodynamic and metabolic study]
Insights
Patients with chest pain and normal coronary arteries may have myocardial ischemia, indicated by impaired lactate extraction during pacing. This metabolic sign helps identify true angina in those with normal coronary arteries, despite normal hemodynamics.
Area of Science:
- Cardiology
- Clinical Physiology
- Biochemistry
Context:
- Chest pain is a common symptom requiring diagnosis.
- Coronary artery disease is often suspected but not always present.
- Normal coronary arteries in patients with angina-like chest pain present a diagnostic challenge.
Purpose:
- To investigate myocardial lactate metabolism in patients with chest pain and normal coronary arteries.
- To differentiate between patients with and without myocardial ischemia using lactate extraction.
- To explore the physiopathology of angina in patients with normal coronary arteries.
Summary:
- Sixty patients with chest pain and normal coronary arteries were studied using atrial pacing and myocardial lactate metabolism analysis.
- Two groups were identified: normal lactate extraction (n=40) and low lactate extraction (n=20), indicating myocardial ischemia.
- Patients with low lactate extraction exhibited typical angina symptoms and electrocardiographic changes, suggesting true myocardial ischemia despite normal coronary hemodynamics.
Impact:
- Identifies a subgroup of patients with angina and normal coronary arteries who experience myocardial ischemia.
- Highlights the utility of myocardial lactate metabolism in diagnosing ischemia when coronary angiography is normal.
- Suggests that the physiopathology of ischemia in these patients is not explained by coronary hemodynamics alone.
Abstract:
Sixty patients without organic heart disease presenting with chest pain suggestive of angina pectoris and angiographically normal coronary arteries underwent clinical, hemodynamic and metabolic investigation. The study of myocardial lactate metabolism during atrial pacing (168 +/- 14 bpm) allowed identification of two groups: --40 patients with a normal coefficient of lactate extraction (K greater than or equal to 9 per cent); --20 patients with a pathologically low coefficient of lactate extraction (K less than 9 per cent) reflecting myocardial ischemia. In the first group, chest pain was often atypical (75 per cent of cases). Hemodynamic investigation showed minor abnormalities of the left ventricle in 48 per cent of cases. The diagnosis of angina was rejected in these patients. In the second group, the majority of patients developed chest pain (85 per cent of cases) at the maximal heart rate with significant ST depression (80 per cent of cases). The chest pain was typical of angina pectoris in 50 per cent of cases. Hemodynamic and angiographic investigation of the left ventricle was completely normal in nearly all cases. Only these patients with clinical, electrocardiographic and metabolic signs of myocardial ischemia can be considered as having angina with normal coronary arteries. Although studies of myocardial lactate metabolism and other signs of myocardial ischemia distinguish clearly between these two groups of patients, the coronary hemodynamics were similar. Resting coronary flow, its increase for the same myocardial oxygen demands and coronary resistances were comparable in both groups, and not significantly different from the values obtained in a control group of patients without coronary artery disease or chest pain. These results confirm that about 30 per cent of patients investigated for chest pain suggestive of angina pectoris who have angiographically normal coronary arteries, develop signs of myocardial ischemia during atrial pacing. The physiopathological explanation remains unclear as coronary hemodynamics have been found to be normal.