To test the hypothesis that acute subarachnoid hemorrhage is associated with abnormal myocardial perfusion, we assessed myocardial blood flow with thallium scintigraphy in 19 patients with a confirmed subarachnoid hemorrhage and an abnormal electrocardiogram. A thallium scan was performed at the bedside of each patient 3 +/- 2 days (mean +/- SD) after subarachnoid hemorrhage and subsequently was analyzed both qualitatively and quantitatively. Patients averaged 58 +/- 13 yr of age and 68% had one or more cardiac risk factors. The neurologic condition of patients on the day of the scan was II (median; range I-V) on the standard 5-point scale of Botterell. Abnormalities on a standard 12-lead electrocardiogram obtained on the same day as the scan consisted of repolarization changes in most patients; 10 had T wave inversions and 8 had nonspecific ST segment changes. Thirty-two percent (n = 6) of patients had an abnormal thallium scan. There were, however, no features of the clinical history, electrocardiogram pattern, or neurologic condition that were associated with a positive scan. For instance, 2 of 4 patients with diffuse deeply inverted T waves had a normal thallium scan, whereas the scan was abnormal in 2 of 8 patients with minor nonspecific electrocardiographic abnormalities. The thallium scan was also positive in neurologically intact (grade I) as well as severely injured (grade V) patients. Thus, abnormal myocardial perfusion and possibly myocardial ischemia occur frequently following subarachnoid hemorrhage, but no specific electrocardiographic characteristic identifies patients with a perfusion abnormality.