Recently we proposed a topographical classification of myocardial infarction (MI) based on the site and extension of left ventricular asynergy (AS) detected by Two-dimensional Echocardiography (2D ECHO) at rest: a) Anterior MI: 1) apical MI with AS of apical segments only, 2) apico-septal MI with AS of apex and septum, 3) apico-septo-lateral MI with involvement of septum, apex and antero-lateral wall. b) Inferior MI: 1) isolated inferior MI with involvement of infero-dorsal wall segments; 2) infero-apical MI with AS of inferior wall and apex, 3) infero-apico-septal MI with kinetic abnormalities of inferior wall, apex and septum and finally c) antero-inferior MI with large AS of septum, apex, antero-lateral and inferior wall. In order to validate the functional significance of this classification, 2D ECHO at rest and symptom limited bicycle ergometric test (E) in supine position with EC-Graphic and hemodynamic monitoring (Swan-Ganz cath.), were performed in the same day within two months after a first transmural MI, in 259 patients, I-II NYHA classes. Among anterior MIs, diastolic pulmonary arterial pressure (PAedP) at rest was normal and similar in apical and apico-septal MIs (11 +/- 3 mmHg). It was significantly (p less than .001) higher 14 +/- 5 mmHg in apico-septo-lateral MIs. Left ventricular stroke work index (LVSWI) was higher in apical MIs (55 +/- 14) than in apico-septal (47 +/- 12, p less than .01) and in apico-septo-lateral MIs (38 +/- 9, p less than .001). Maximal work load during E was 86 +/- 31 watt in apical MIs, 77 +/- 29 watt in apico-septal MIs and 70 +/- 25 in apico-septo-lateral MIs with significant difference (p less than .05) only between the last ones and apical MIs. The PAedP during E was normal (20 +/- 7 mmHg) in apical MI, but increased abnormally in apico-septal (24 +/- 7 mmHg) and in apico-septo-lateral (27 +/- 7 mmHg) with a significant difference (p less than .01) only between apical and apico-septo-lateral MIs. In inferior MIs, hemodynamic data at rest were similar in pts with isolated inferior, infero-apical and infero-apico-septal MIs. Maximal work load, similar in inferior and infero-apical MI (88 +/- 30 W) was higher (p less than .01) than in infero-apico-septal (68 +/- 22W).(ABSTRACT TRUNCATED AT 400 WORDS)