<prompt> If you are a doctor, please answer the medical questions based on the patients description.my husband had a thallium treadmill...results show a spot on the left ventrical...he is now scheduled for a heart cath..the spot? exactly what is this indicating? He has a long hx of heart disease, DM, pacemaker...at 60 WM...his 2st MI was at age 36...  <response>: Hello the spot on thallium perfusion scan may indicate two things, an old infarct which may have been a result of the previous myocardial infarction he had. However, considering he has been planned for and path study, it probably would mean that it is secondary to active ischemia a decreased supply to that area of the heart . A thallium is able to differentiate between the two and do provide a more detailed report for helping you with the differentiation. Regards Chat Doctor. 