The cardiologist required the nuclear stress test to rule out any heart problems before clearing the person to have thyroid meds for hypothyroidism because they have intermittent hypertension and higher than normal cholesterol and he is afraid thyroid meds could be dangerous. Now the finding of a slight "dark spot" has him saying a catheterization is required because the stress test was inconclusive. Doesn't the scan result of zero rule out blockages? Is there any other way to identify the "dark spot"?