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Syndrome X: diagnostic criteria and long term prognosis
Insights
Syndrome X is characterized by reduced coronary reserve and myocardial cell changes. Left ventricular function is normal at rest but impaired during stress, with some patients experiencing progressive deterioration.
Area of Science:
- Cardiology
- Cardiovascular Physiology
Background:
- Syndrome X presents with reduced coronary reserve, indicating impaired dilatory capacity of coronary resistance vessels.
- Myocardial cells show degenerative changes on electron microscopy, while intramyocardial vessels remain normal.
- Left ventricular function is preserved at rest but compromised during various forms of stress.
Purpose of the Study:
- To characterize the physiological and cellular abnormalities in Syndrome X.
- To highlight the diagnostic significance of reduced coronary reserve in Syndrome X.
- To investigate the long-term prognosis and heterogeneity within Syndrome X patient cohorts.
Main Methods:
- Assessment of coronary reserve and left ventricular function under resting and stress conditions.
- Electron microscopy for evaluating myocardial cell structure.
- Analysis of T1-wash out and glutamate turnover.
- Longitudinal follow-up of patients, including those with co-existing left bundle branch block.
Main Results:
- Patients exhibit a significant reduction in coronary reserve.
- Electron microscopy reveals degenerative changes in myocardial cells.
- Left ventricular function declines during stress.
- Delayed T1-wash out and increased glutamate turnover are observed.
- A subset of patients with left bundle branch block shows progressive left ventricular dysfunction.
Conclusions:
- Reduced coronary reserve is a key diagnostic marker for Syndrome X.
- Syndrome X involves myocardial cellular pathology and impaired cardiac function under stress.
- Patient outcomes can be heterogeneous, with specific subgroups facing progressive decline.
Abstract:
Patients with syndrome X have an appreciable reduction in coronary reserve, i.e. the dilatory capacity of the coronary resistance vessels. Whereas the intramyocardial vessels are normal, there are degenerative changes in myocardial cells, shown on electron microscopy. Left ventricular function is normal under resting conditions but becomes abnormal during isometric or dynamic stress. The diagnosis of syndrome X is predominantly based on a marked reduction in coronary reserve. Furthermore, delayed T1-wash out and increased glutamate turnover have been observed. Follow-up studies reveal some heterogeneity of patients studied; in patients with syndrome X and left bundle branch block left ventricular function deteriorates progressively.