Left ventricular hypercontractility and ST segment depression in patients with syndrome X

Area of Science:

• Cardiology
• Exercise Physiology

Background:

• Syndrome X (chest pain with normal coronary arteries) can present with high rest left ventricular ejection fraction.
• Understanding the relationship between left ventricular function and exercise capacity is crucial for managing these patients.

Purpose of the Study:

• To assess the correlation between rest left ventricular function and exercise capacity in patients diagnosed with syndrome X.
• To investigate the electrocardiographic (ECG) changes during exercise in relation to left ventricular ejection fraction.

Main Methods:

• Studied 37 patients with syndrome X (angina, normal coronary arteries, positive exercise test).
• Assessed left ventricular function via angiography, exercise capacity (duration, heart rate), and 24-hour ambulatory ECG monitoring.
• Patients discontinued all treatments for at least 48 hours prior to testing.

Main Results:

• Left ventricular hypercontractility (ejection fraction ≥ 80%) was found in 32% of patients.
• Patients with hypercontractility experienced earlier ST segment depression (5.13 min vs. 10.76 min) and greater magnitude of depression (2.03 mm vs. 1.33 mm) during exercise.
• A significant negative correlation was observed between exercise duration and ejection fraction (r = 0.55, p < 0.001).

Conclusions:

• About one-third of syndrome X patients have left ventricular hypercontractility.
• This hypercontractility is associated with earlier onset and slower resolution of exercise-induced ST segment depression.
• Findings suggest a link between enhanced contractility and impaired exercise response in syndrome X.