Prognostic significance of scintigraphic silent myocardial ischemia detected by stress thallium scan in patients with recent myocardial infarction

To evaluate the prognostic significance of scintigraphic silent myocardial ischemia (SMI) detected by stress thallium scan in patients with myocardial infarction (MI), we performed a retrospective investigation on cardiac events (CE) during a two-year follow-up period in 149 patients with MI within three months of onset (34±19 days). SMI was defined as asymptomatic redistribution (RD) in the infarcted area. The patients were divided into three groups based on results of stress thallium scan as follows: 50 patients with neither chest pain nor RD (Group A), 46 patients with SMI (Group B) and 53 symptomatic patients (Group C). In comparison of the incidence of CE, which included cardiac death, recurrent MI, chronic heart failure, angina pectoris, PTCA, CABG and severe ventricular arrhythmia (low grade≥3) during two-year follow-up, Group C had significantly higher incidence of percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass graft (CABG) than Group B (p<0.01), but there was no significant difference of other CE between groups B and C except PTCA and CABG. In addition, Groups B and C had a significantly higher incidence of CE than Group A in cardiac event-free curves, but there was no significant difference for Groups B and C. We conclude that patients with SMI are associated with unfavorable prognosis as symptomatic patients and that these patients should undergo careful follow-up. (author)