How does delaying treatment affect the long-term prognosis for patients with acute myocardial infarction treated with primary coronary angioplasty?

Background: The benefit of thrombolysis in patients with acute myocardial infarction (AMI) strongly depends on the time from the onset of symptoms to the initiation of treatment. For AMI patients treated with percutaneous coronary interventions (PCI) this delay of treatment seems to be important only up to a certain time level. Aim: To assess the effects of time to treatment of AMI with PCI on the short- and long-term prognosis. Methods: We followed 339 consecutive AMI patients treated with PCI from 1995 to 1999 in our centre. Patients were divided into five groups according to the time to treatment and ischaemic time (time from symptom onset to reperfusion). Results: Time to treatment 691 min in 53 (15.5%) patients. According to ischaemic time, the patients were divided into groups: 12 h. The ejection fraction of the left ventricle 3-5 days after AMI was 50%, 51%, 45%, 40%, and 46%, and the 30 day mortality - 5.7%, 2.9%, 11.1%, 10.8%, and 11.3%, respectively. Compared with patients treated later, patients with time to treatment Conclusions: The success rate of primary PCI to achieve normal flow in an infarct-related artery is high, but it decreases when treatment is started later than 3,5 h from AMI onset. The short-term and long-term mortality as well as the incidence of heart failure during the acute phase of MI are the lowest when PCI is started within 3,5 h from the onset of symptoms.