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[Does syndrome X exist?]
1Service de cardiologie A, CHU La Timone, Marseille.
Insights
Syndrome X, characterized by chest pain and positive stress tests in patients with normal coronary arteries, is a real entity. However, its incidence is often overestimated due to inconsistent diagnostic criteria, particularly regarding coronary artery spasm and myocardial hypertrophy.
Area of Science:
- Cardiology
- Clinical Medicine
- Diagnostic Criteria
Context:
- Syndrome X, also known as INOCA (Ischemia with Non-Obstructive Coronary Arteries), presents diagnostic challenges.
- Accurate diagnosis requires excluding other causes of angina with normal coronary arteries, such as coronary artery spasm and myocardial hypertrophy.
Purpose:
- To evaluate the adherence to diagnostic criteria for Syndrome X in existing literature.
- To determine the actual incidence of Syndrome X based on rigorous exclusion of confounding conditions.
Summary:
- A literature review of 26 studies (822 patients) revealed inconsistent application of diagnostic criteria for Syndrome X.
- A positive exercise stress test was an inclusion criterion in only 38.1% of studies.
- Coronary spasm and myocardial hypertrophy were formally excluded in only 33.3% and 27.7% of patients, respectively.
- After applying strict criteria, only 17.4% of patients could be definitively diagnosed with Syndrome X, suggesting overestimation.
Impact:
- Highlights the need for standardized diagnostic criteria for Syndrome X to improve diagnostic accuracy.
- Emphasizes the importance of differentiating Syndrome X from other conditions causing exertional chest pain with normal or non-diagnostic stress tests.
- Contributes to a clearer understanding of the prevalence and diagnosis of INOCA.
Abstract:
The syndrome X is an entity characterised by the association of chest pain on exercise and a positive exercise stress test in patients with normal coronary angiography. However, this diagnosis can only be admitted when all other causes of angina with normal coronary arteries have been excluded. They include angina secondary to coronary artery spasm and myocardial hypertrophy. A review of the literature based on 26 publications recensing 822 patients shows that these criteria are not always respected: a really positive exercise stress test is an inclusion criterion in only 13 studies and concerns only 313 patients (38.1%); myocardial hypertrophy and coronary spasm were formally excluded in only 278 (33.3%) and 228 patients (27.7%) respectively. Taking into consideration only the patients of these 26 series with a positive exercise stress test after exclusion of coronary spasm and myocardial hypertrophy, 143 (17.4%) may be considered to be due to syndrome X. Syndrome X is a real entity but its incidence is usually overestimated. It is appropriate to distinguish it from other conditions associating, though the exercise stress test is negative, chest pain on effort and the positivity of a test considered to be indicative of myocardial ischaemia.