Examination of the Appropriate Timing of Reperfusion Therapy for Recent Myocardial Infarction: a Japanese Single-center Retrospective Study

Background: The various guidelines clearly mention the treatment strategies for in patient of acute myocardial infarction (MI) presenting more than 24h from symptom onset (recent myocardial infarction, RMI). However, the appropriate timing of reperfusion for RMI is unclear.

Methods: We retrospectively evaluated 525 consecutive MI patients who underwent percutaneous coronary intervention (PCI) in our hospital between January 2008 and December 2012.

Results: Sixty RMI patients were more frequently associated with cardiac complications such as myocardial rupture (3.3% vs. 0%; p<0.01), ventricular septal rupture (3.3% vs. 0.4%; p<0.05), and congestive heart failure (15% vs. 2.6%; p<0.001) than 272 consecutive ST-elevation myocardial infarction (STEMI) patients. Of the 60 RMI patients, 33 (55.0%) underwent PCI within 7days (early-PCI group) and 27 (45.0%) underwent PCI after 7days (late-PCI group). Left ventricular ejection fraction measured by echocardiography at second hospital day was similar between the groups. The early-PCI group was more significantly associated with cardiogenic shock and heart failure and more frequently required intra-aortic balloon pumping (24.2% vs. 3.7%; p<0.05) than the late-PCI group. There were no significant differences in 30-day mortality, cardiac complications, and major cardiac events during long-term follow-up (12-36 months) between the groups.

Conclusion: RMI patients had a higher incidence of cardiac complications than AMI patients. Clinical outcomes were similar between patients undergoing early revascularization and those undergoing late revascularization, although the former group included a higher proportion of patients with severe cardiac failure.