[Myocardial adaptation to ischemia. A study during repeated prolonged coronary occlusions in angioplasty].

Coronary angioplasty provides an ideal model for studying ischemic preconditioning in humans. Four coronary occlusions, each lasting 5.2 +/- 1.3 min, separated by 3 min of reperfusion, were performed during angioplasty of isolated stenosis of the left anterior descending artery of 18 patients with stable angina and normal left ventricular function. The ischaemia was evaluated and compared during the first and fourth coronary occlusion with the aid of clinical, electrocardiographic, echocardiographic and metabolic parameters. We analysed: 1) interval to chest pain and its intensity; 2) degree of ST change on the intracoronary electrocardiogram; 3) regional wall motion abnormalities on 2D echocardiography; 4) coefficient of myocardial lactate extraction. The results showed that during the fourth occlusion: chest pain occurred later (93 +/- 57 vs 60 +/- 49 s; p < 0.05) and ST elevation was less (0.69 +/- 0.5 vs 1.03 +/- 0.8; p < 0.05). During the fourth occlusion, there was a delay in appearance and a decrease in the regional wall motion abnormalities: anterior wall hypokinesia occurred later: 26 +/- 15 vs 19 +/- 19 s (p = 0.08). Akinesia observed in 10 patients out of 13 (77%) during the first occlusion, was only observed in 8 patients (62%) and dyskinesia, observed in 5 patients out of 13 (38%) during the first occlusion was not observed thereafter in any patient. The production lactate was less important during the fourth occlusion than during the first one: -3 +/- 17% vs -12 +/- 19% (p < 0.05). This study confirms that, in man, preconditioning allows myocardial adaptation to successive episodes of acute ischaemia.