Syndrome X
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Chronic stable angina Microchapters | ||
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Classification | ||
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Differentiating Chronic Stable Angina from Acute Coronary Syndromes | ||
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Diagnosis | ||
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Alternative Therapies for Refractory Angina | ||
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Discharge Care | ||
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Guidelines for Asymptomatic Patients | ||
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Case Studies | ||
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Syndrome X On the Web | ||
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
The terms Syndrome X or Metabolic syndrome X may also be referring to metabolic syndrome.
Synonyms and key words: Microvascular angina
Overview
(Cardiac) syndrome X is angina (chest pain) associated with objective evidence of myocardial ischemia in the absence of epicardial coronary artery disease. The disorder has been hypothesized to be a disorder of the coronary microvasculature rather than the large caliber epicardial coronary arteries.
Pathophysiology
In a large percentage of patients, there is microvascular dysfunction.
Epidemiology and Demographics
Syndrome X occurs more often in young women. Some studies have found an increased risk of other vasospastic disorders in syndrome X patients, such as migraine and Raynaud's phenomenon.
Natural history, complications, and prognosis
Syndrome X does not appear to be associated with an excess of major coronary events.
Risk Factors
Female gender and hypertrophy of the myocardium are associated with an excess risk of Syndrome X.
Other Conditions to Distinguish Syndrome X From
Syndrome X should be distinguished from Prinzmetal's angina, a disorder which involves spasm of the main epicardial coronary arteries. Syndrome X involves dysfunction of the downstream microvasculature. Syndrome X must also be distinguished from esophageal spasm.
Diagnosis
Syndrome X is a diagnosis of exclusion. The diagnostic criteria are as follows:
- There must be evidence of myocardial ischemia: Diagnostic studies include an exercise ECG, stress scintigraphy, or stress echocardiography in conjunction with anginal chest discomfort.
- Angina: Angina pectoris must be present. The angina pectoris associated with Syndrome X may last longer that the anginal discomfort associated with the fixed epicardial stenoses of atherosclerotic heart disease.
- Abnormal Cardiac stress test: ST changes are typically similar to those of coronary artery disease and opposite of those with Prinzmetal's angina. Myocardial perfusion imaging can be abnormal in 30% of patients.
- Coronary angiogram: There is no narrowing of the epicardial arteries. However, Syndrome X may be associated with a reduction in coronary vasodilator reserve presumably due to abnormalities in the coronary microcirculation. During stress, sampling of the coronary sinus demonstrates the production of lactate by the myocardium. Intracoronary acetylcholine can be administered to evaluate endothelium-dependent coronary flow reserve.
ESC Guidelines for investigation in patients with Syndrome X (DO NOT EDIT)[1]
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Class I1. Resting echocardiogram in patients with angina and normal or non-obstructed coronary arteries to assess for presence of ventricular hypertrophy and/or diastolic dysfunction. (Level of Evidence: C) Class IIb1. Intracoronary acetylcholine during coronary arteriography, if the arteriogram is visually normal, to assess endothelium-dependent coronary flow reserve, and exclude vasospasm. (Level of Evidence: C) 2. Intracoronary ultrasound, coronary flow reserve, or FFR measurement to exclude missed obstructive lesions, if angiographic appearances are suggestive of a nonobstructive lesion rather than completely normal, and stress imaging techniques identify an extensive area of ischaemia. (Level of Evidence: C) |
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Treatment
The mainstay of treatment in patients with Syndrome X are calcium channel blockers, such as nifedipine and diltiazem. Other therapies include:
- Nitrates
- Beta blockers
- Aminophylline - may be effective via inhibition of adenosine receptors.
- Estrogen - may be effective in women.
ESC Guidelines for pharmacological therapy to improve symptoms in patients with Syndrome X (DO NOT EDIT)[1]
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Class I1. Therapy with nitrates, beta blockers, and calcium channel blockers alone or in combination. (Level of Evidence: B) 2. Statin therapy in patients with hyperlipidaemia. (Level of Evidence: B) 3. ACE inhibitors in patients with hypertension. (Level of Evidence: C) Class IIa1. Trial of therapy with other anti-anginals including nicorandil and metabolic agents. (Level of Evidence: C) Class IIb1. Aminophylline for continued pain, despite Class I measures. (Level of Evidence: C) 2. Imipramine for continued pain, despite Class I measures. (Level of Evidence: C) |
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References
- ↑ 1.0 1.1 Fox K, Garcia MA, Ardissino D, Buszman P, Camici PG, Crea F; et al. (2006). "Guidelines on the management of stable angina pectoris: executive summary: The Task Force on the Management of Stable Angina Pectoris of the European Society of Cardiology". Eur Heart J. 27 (11): 1341–81. doi:10.1093/eurheartj/ehl001. PMID 16735367.