Doppler echocardiographic evaluation of the effect of atrial pacing-induced ischemia on left ventricular filling in patients with coronary artery disease

Very little is known about the effects of acute myocardial ischemia on left ventricular filling. Previous studies of these effects have been of limited value because they were performed with 1) imaging techniques that, like cineventriculography or radionuclide ventriculography, do not allow beat to beat monitoring of left ventricular filling throughout the entire ischemic attack; and 2) exercise, which, even if effective in inducing myocardial ischemia in patients with coronary artery disease, also considerably shortens cycle length, thus leading to additional nonischemic filling alterations. To overcome these limitations, left ventricular filling was studied by means of Doppler echocardiographic evaluation of transmitral flow velocities before and immediately after rapid atrial pasing in 17 patients. Eight patients had coronary artery disease but did not develop ischemia 1ST depression ≥1.5 mm) during atrial pacing (Group D whereas nine had corodary artery disease and developed ischemia during atrial pacing (Group 2). No differences were observed from rest to postpacing in any of the filling varlables considered in Group 1 patients. In contrast, a significant rearrangement of left ventricular filling occurred during ischemia in Group 2 patients. Early peak flow veiocity decreasad (from 55 ± 8 to 48 ± g cm/s, p < 0.01), atrial peak flow velocity increased (from 57 ± 10 to 72 ± 15 cm/s, p < 0.01), the ratio of early peak flow velocity to atrial peak flow velocity decreased (from 0.98 ± 0.19 to 0.68 ± 0.15, p < 0.01) and the percent contribution of atrial contraction to overall left ventricular filling increased (from 35.9 ± 7.2 to 40.5 ± 6.9, p < 0.05). During ischemia, cardiac output was unchanged owing to a compensatory atrial filling contribution. Continuous monitoring of postpacing recovery period showed that filling alterations gradually returned to preischemia values; 1 min after cessation of atrial pacing there were no more significant changes in any of the filling veriables considered. Thus, 1)during acute ischemia, left ventricular filling is momentarity rearranged and, because of this, the atrial contribution becomes more important; and 2) Doppler evaluation of transmitral blood flow velocities before and after incremental atrial pacing is a useful tool for evaluating lefl ventricular filling changes induced by acute ischemia and their recovery modalities.