Brief Answer: please see details Detailed Answer: Respected Ma'm 1. Yes, Stress thallium is associated with certain risks like all other stress tests (namely stress ECHO or exercise ECG). Since It's aim is to induce angina, it may cause prolonged angina, heart attack, fatal increase in heart rate. But fortunately these events occur in 1 in 0000 patients. Beside the side effects of method used to give stress may occur. Physical injury in treadmill, hypersensitivity reaction in dobutamine stress ECHO etc may occur. Although these occur at very low rate. 2. The Diagnostic test for heart function are ECHO, MUGA scan, Baseline Thallium scan. For blockage in blood vessels there are direct tests (CT coronary angiogram & conventional catheter angiogram) and indirect tests (all type of stress tests). These should be done only under the advise of your cardiologist. One should not go for them on her own. 3. There is no point in knowing if you have a blockade or not, until you have some symptoms suggestive of same. You doctor is best judge to decide if you really require a test. Knowing blockage does not assure or predict future heart attacks in any manner (positive or negative). LBBB (left bundle branch block) is an electrical phenomenon and it has no direct relation with blockage of vessels. Mostly it lasts for whole life. It can be seen on a simple ECG (electrocardiogram). Sincerely Sukhvinder

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