Indium-111 antimyosin scintigraphy was performed in 24 consecutive patients after percutaneous transluminal coronary angioplasty to assess whether repeated periods of ischaemia during balloon inflation results in myocardial cell damage even after a successful procedure. Patients with unstable angina, prior myocardial infarction and whose procedure was complicated were excluded. Indium-111 monoclonal antimyosin antibodies (80 MBq) were injected 24 h after coronary angioplasty and planar images were collected 24 h later. The relative antimyosin uptake was assessed subjectively and by a heart/lung count density ratio. In addition, the intracardiac gradient of activity was assessed by a count density profile analysis of the cardiac region of interest to distinguish better the focal as opposed to the diffuse antimyosin uptake. The antimyosin uptake index was calculated by multiplying the heart/lung ratio to the intracardiac gradient of activity. After coronary angioplasty, nine patients had minor ST-T wave changes on the surface ECG, but no patient demonstrated a new Q wave. Only three patients showed a mild rise in cardiac enzyme (CK-MB) serum levels. Indium-111 antimyosin uptake (heart/lung > 1.55) was present in eight patients (33%) and was intense (heart/lung > 1.9) in five (21%). Antimyosin uptake was always seen in myocardial segments corresponding to the treated coronary artery. Patients with a positive antimyosin scan had a longer duration of balloon-induced ischaemia compared with patients with no evidence of antimyosin uptake (541 +/- 211 vs 331 +/- 137 s, P < 0.007).(ABSTRACT TRUNCATED AT 250 WORDS)