Cardiac syndrome X

Overview

Cardiac Syndrome X, also known as Microvascular Angina, is a form of angina (chest pain) that occurs despite normal-appearing coronary arteries on angiography. Patients experience symptoms similar to those of coronary artery disease (CAD), such as chest discomfort or shortness of breath, but without evidence of major blockages in the large coronary arteries. The condition is believed to be caused by dysfunction of the small coronary arteries (microvasculature), which are not easily visible on standard imaging tests. Cardiac Syndrome X is more common in women, particularly postmenopausal women.

Causes

The exact cause of Cardiac Syndrome X is not completely understood, but several factors are believed to contribute to microvascular dysfunction:

• Endothelial dysfunction: Impaired function of the endothelium (lining of blood vessels), which affects vascular tone and blood flow

• Inflammation: Low-grade inflammation may contribute to vessel narrowing or poor dilation

• Hormonal changes: Particularly estrogen deficiency in postmenopausal women

• Autonomic nervous system imbalance: May lead to abnormal regulation of blood flow in small vessels

• Insulin resistance and metabolic syndrome: Often coexisting with this condition

Symptoms

Patients with Cardiac Syndrome X typically present with signs and symptoms similar to those of traditional angina, including:

• Chest pain or pressure (angina), often brought on by exertion or stress

• Shortness of breath

• Fatigue, especially during physical activity

• Discomfort may last longer than typical angina and may not always be relieved by rest or nitroglycerin

• Normal ECG and cardiac enzymes during episodes in many cases

These symptoms can significantly affect quality of life and are often frustrating for patients due to the lack of visible arterial blockages on tests.

Diagnosis

Cardiac Syndrome X is diagnosed based on the exclusion of obstructive coronary artery disease. Diagnostic steps include:

• Exercise stress testing: To provoke symptoms and monitor heart response to exertion

• Coronary angiography: Shows normal or non-obstructive coronary arteries despite symptoms

• Cardiac MRI or PET scan: May be used to evaluate blood flow in the heart's microvasculature

• Coronary flow reserve testing: Measures the ability of small vessels to dilate in response to stress

• Blood tests: To rule out other causes of chest pain or inflammation

The diagnosis is often made after ruling out other potential causes of angina and confirming microvascular dysfunction.

Treatment

Treatment for Cardiac Syndrome X focuses on symptom relief, improving microvascular function, and addressing underlying risk factors. Management may include:

• Lifestyle modifications:

  • Regular aerobic exercise

  • Heart-healthy diet

  • Smoking cessation

  • Stress reduction techniques (e.g., meditation, CBT)

• Medications:

  • Beta-blockers or calcium channel blockers: To improve blood flow and reduce chest pain

  • Nitrates: May help some patients, although responses vary

  • ACE inhibitors or ARBs: To improve endothelial function

  • Statins: For cholesterol management and anti-inflammatory effects

  • Ranolazine: May be used to manage chronic angina symptoms

Prognosis

The long-term outlook for patients with Cardiac Syndrome X is generally favorable, especially compared to those with obstructive coronary artery disease. Although the condition is not usually life-threatening, it can cause persistent chest pain and significantly reduce quality of life. With proper management and lifestyle changes, most individuals can control symptoms and maintain normal daily activities. Ongoing research is improving understanding of the condition, leading to more targeted and effective therapies in the future.