Stress is thought to be a coronary risk factor. The main aim of this study is the quantitative analysis of the psychophysiological and cardiovascular activation induced by mental stress in patients (pts) with recent myocardial infarction (Ml). Twenty one pts with recent Ml, after psychological assessment, underwent two consecutive stressors in random sequence: mental arithmetic and Sacks test, during ECG and right heart hemodynamic monitoring. During both stressors there were significant variations (p less than 0.01) of heart rate (HR), systolic and diastolic (dAP) arterial pressures, rate-pressure product (RPP), right atrial pressure (RAP), pulmonary artery end-diastolic pressure (PAEDP), whereas no significant variations in cardiac output could be measured by thermodilution. Of particular interest was the remarkable increase in PAEDP: from 14 +/- 4 (mean +/- SD) to 21 +/- 6 mmHg during mental arithmetic, and from 15 +/- 6, to 20 +/- 6 mmHg during the Sacks test. Mental arithmetic elicited a greater cardiovascular activation than the Sacks test; the differences between the stressors in HR, dPAP, RAP (p less than 0.05) and RPP (p less than 0.01) were all significant. Mental stress in recent Ml challenges the cardiovascular system in measurable quantity, with remarkable increments of left ventricular filling pressure. Its use is suggested for the functional evaluation of pts with recent Ml, although in such setting mental stress seems to be of little value in revealing ischemia and arrhythmias.