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Syndrome X: the haemodynamic significance of ST segment depression
Insights
Patients with Syndrome X experience chest pain and ST segment depression without impaired left ventricular function. Unlike coronary artery disease, their pulmonary artery pressure does not significantly rise during these episodes.
Area of Science:
- Cardiology
- Cardiovascular Physiology
Background:
- Syndrome X, characterized by angina and ST depression with normal coronary arteries, presents a diagnostic challenge.
- The underlying mechanisms and hemodynamic changes in Syndrome X remain incompletely understood.
Purpose of the Study:
- To investigate the relationship between chest pain, ST segment depression, and left ventricular function in patients with Syndrome X.
- To compare hemodynamic responses during ischemic events in Syndrome X versus coronary artery disease.
Main Methods:
- Assessed six patients with Syndrome X and six controls using treadmill exercise tests and ambulatory pulmonary artery pressure monitoring.
- Compared hemodynamic data (pulmonary artery diastolic pressure) during ST depression and angina episodes in Syndrome X and 19 patients with coronary artery disease.
Main Results:
- Patients with Syndrome X showed ST segment depression during exercise and monitoring without significant changes in pulmonary artery diastolic pressure.
- In contrast, patients with coronary artery disease exhibited a rise in pulmonary artery diastolic pressure during exercise and angina episodes.
- Syndrome X episodes (painful and painless) were not associated with elevated pulmonary artery diastolic pressure, indicating preserved left ventricular function.
Conclusions:
- Chest pain and ST segment changes in Syndrome X are not linked to the typical hemodynamic alterations seen in myocardial ischemia due to coronary artery disease.
- Left ventricular function remains unimpaired during ischemic-like events in Syndrome X, differentiating it from coronary artery disease.
Abstract:
The relation between chest pain, ST segment depression, and changes in left ventricular function was assessed in six patients with angina, a positive exercise test, and normal coronary arteries as assessed by arteriography (syndrome X). In the six patients with syndrome X and in six controls there was no significant rise in pulmonary artery diastolic pressure during treadmill exercise, although there was ST segment depression (range 1-4.5 mm) in the patients with syndrome X. In 19 patients with coronary artery disease, however, the pulmonary artery diastolic pressure increased by a median 5 mm Hg (range 0-13.6 mm Hg) on treadmill exercise. In only one patient with coronary artery disease, who showed 1 mm ST segment depression, was there no rise in pulmonary artery diastolic pressure. During ambulatory monitoring in patients with syndrome X there were 12 episodes of ST segment depression (greater than 1 mm) (4 painful, 8 painless) in which there was no change in pulmonary artery diastolic pressure. In the patients with coronary artery disease there were 29 episodes of angina during ambulatory monitoring and during all of them pulmonary artery diastolic pressure rose by a median 7.5 mm Hg (range 1.8-19.7 mm Hg). Unlike the haemodynamic changes that usually occur during myocardial ischaemia in coronary artery disease, chest pain and ST segment changes in patients with syndrome X are not associated with impaired left ventricular function as assessed by ambulatory pulmonary artery pressure monitoring.