OBJECTIVES: To examine the relationship between the persistence of ST segment depression in leads V5-V6 after Q-wave anterior wall myocardial infarction (MI) and the filling pattern of the left ventricle (LV). BACKGROUND: Precordial ST segment depression predominantly in leads V5-V6 is associated with increased in-hospital morbidity and mortality after acute myocardial ischemia, perhaps due to reduced diastolic distensibility of the LV. METHODS: We prospectively studied 19 patients after Q-wave anterior wall MI (>6 months). All patients underwent 12-lead ECG recording, symptom-limited treadmill exercise testing with single photon emission computed tomography thallium-201 imaging, transthoracic Doppler echocardiography, cardiac catheterization and measurement of circulating atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) levels. Patients were classified based on the presence of ST segment depression in leads V5-V6: Group I = ST segment depression <0.1 mV (n = 10); Group II = ST segment depression ≥0.1 mV (n = 9). RESULTS: Patients in Group II had greater LV end diastolic pressures (32.4 ± 6.5 mm Hg vs. 14.8 ± 6.1 mm Hg; p = 0.0001), higher plasma ANP (44.4 ± 47.1 pg/ml vs. 10.7 ± 14 pg/ml; p = 0.04) and BNP levels (89.4 ± 62.7 pg/ml vs. 23.6 ± 33.1 pg/ml; p = 0.01), greater left atrium area (20.6 ± 3.1 cm2 vs. 17.8 ± 2.4 cm2; p = 0.05), lower peak atrial (A), higher early (E) mitral inflow velocities, a higher E/A ratio and a lower deceleration time (167 ± 44 ms vs. 220 ± 40 ms; p = 0.05). Lung thallium uptake during exercise was more common in Group II (78% vs. 10%, p = 0.04). CONCLUSIONS: Persistent ST segment depression in leads V5-V6 in survivors of Q-wave anterior wall MI is associated with increased LV filling pressure and a restrictive LV filling pattern. (C) 2000 by the American College of Cardiology.