Significance of hyperventilation-induced st segment depression in patients with coronary artery disease

To investigate the significance of hyperventilation-induced ST segment depression, 329 consecutive patients with angina and documented coronary artery disease who underwent hyperventilation and exercise tests during pharmacologic washout were studied. The hyperventilation test induced ST segment depression in 79 patients. In 36 of these 79 patients; the electrocardiographic changes occurred early during overbreathing (Group I), whereas in 26 they occurred late during recovery (Group II). Seventeen patients developed ST segment depression both during overbreathing and during recovery (Group III).