NEW-ONSET ANGINA PRECEDING ACUTE MYOCARDIAL-INFARCTION IS ASSOCIATED WITH IMPROVED CONTRACTILE RECOVERY AFTER THROMBOLYSIS

Background Ischaemic preconditioning reduces myocardial infarct size i n animal models. Clinical data suggest that episodes of angina immedia tely before acute myocardial infarction may be associated with smaller infarct size in man. However, it is unclear whether ischaemic episode s preceding acute myocardial infarction also affect contractile recove ry in patients. Objective In this study we investigated the recovery o f regional myocardial function after thrombolysis in two groups of pat ients at their first Q-wave acute myocardial infarction; in one group (n=42) myocardial infarction occurred unheralded, whereas patients of the second group (n=48) had experienced new-onset angina in the 48 h t hat preceded infarction. Echocardiographic analysis of myocardial regi onal function in the infarct area was done at 2, 24 and 72 h after thr ombolysis, and at 1 week, and 1 and 3 months follow-up. Results Peak l evel of MB-creatine kinase was significantly lower in patients with ne w-onset angina (96 +/- 47 as compared with 221 +/- 108 IU.l(-1), P<0.0 1), as was the area under the MB-creatine kinase curve (1321 +/- 876 a s compared to 3879 +/- 1555 U.l(-1)/36 h, P<0.01). Hypokinetic segment s were fewer in patients with pre-infarction angina. Similarly, wall m otion score improved significantly earlier in patients who had new-ons et angina before acute myocardial infarction. Thus, contractile recove ry was more rapid in patients with previous angina than in those in wh om infarction occurred unheralded. Complications during the in-hospita l outcome and other variables considered during the 4-week follow-up w ere similar between groups. Conclusions Patients who experienced new-o nset angina before acute myocardial infarction showed better recovery of regional function after thrombolysis. Our study supports the hypoth esis that brief periods of ischaemia immediately before myocardial inf arction may precondition the human heart, thus improving contractile r ecovery.