Effect of Sublingually Administered Isosorbide Dinitrate on Ischemic Injury in Patients with Acute Myocardial Infarction

Abstract

To evaluate reversible myocardial ischemic areas in acute myocardial infarction (AMI), we have developed the following methods : (1) 2mCi of thallium-201 was injected intravenously and myocardial per fusion images were obtained ; (2) immediately thereafter, 5 mg of isosorbide dinitrate (ISD) was administered sublingually ; and (3) 10 minutes after the administration, another bolus of 2 mCi of thallium-201 was given and myocardial per fusion imaging was repeated (double scan method). Ten patients with AMI (within 24 hours after onset) were studied by the double scan method. Myocardial per fusion defect areas were reduced from 29±3% of the entire left ventricle to 19±4% by ISD administration, indicating that there were reversibly ischemic areas in AMI which could be transiently reduced by ISD. For clinical implication, 80 patients with AMI were divided into 2 groups at random : Group I-40 patients treated with conventional methods, and Group II-40 patients treated with continuos ISD administration (every 3 hours for 3 days). There was no significant difference in prognostic indices at the time of admission. Final MI sizes estimated by thallium-201 2 months after onset (percent of per fusion defects to the total left ventricle) were significantly smaller in Group II (19.8±3.1%) than in Group I (32.1±3.7%) (p<0.02). Mortality was 25% in Group I and 10% in Group II. This preliminary report indicates that nitrates have possibly beneficial action in decreasing ischemic injury of acute myocardial infarction.