political activist garry kasparov is here. you're watching the "closing bell" on cnbc, first in business worldwide. mber the day my doctor told me i have an irregular heartbeat, and that it put me at 5-times greater risk of a stroke. i was worried. i worried about my wife, and my family. bill has the most common type of atrial fibrillation, or afib. it's not caused by a heart valve problem. he was taking warfarin, but i've put him on pradaxa instead. in a clinical trial, pradaxa 150 mgs reduced stroke risk 35% more than warfarin without the need for regular blood tests. i sure was glad to hear that. pradaxa can cause serious, sometimes fatal, bleeding. don't take pradaxa if you have abnormal bleeding, and seek immediate medical care for unexpected signs of bleeding, like unusual bruising. pradaxa may increase your bleeding risk if you're 75 or older, have a bleeding condition like stomach ulcers, or take aspirin, nsaids, or bloodthinners, or if you have kidney problems, especially if you take certain medicines. tell your docto