Effects of left ventricular chamber size and left ventricular diastolic pressure on left atrial booster pump function in patients with old myocardial infarction.

We characterized the influence of the size of the left ventricular (LV) chamber (LV diastolic diameter, LVDD) and LV end-diastolic pressure (LVEDP) on left atrial active stroke index (LAASI) in patients with old myocardial infarction (OMI) (n = 118) and controls (n = 25). Patients with OMI were classified into four groups according to the grade of LVDD (> or = 55 or < 55 mm) and LVEDP (> or = 18 or < 18 mmHg). LAASI was determined by multiplying the LV stroke index by the fraction of left atrial active contraction of the velocity-time integral on the pulsed-wave Doppler echocardiogram. LAASI in the "LVDD > or = 55 & LVEDP > or = 18" group was less than that in the groups with normal LVEDP. LAASI did not differ among the normal LV dimension groups. The combination of LV enlargement and high LVEDP was related to the decrease in LAASI in patients with OMI.