 Hundreds of flights already canceled today, many of them on Delta. The airline had to cancel about 1,400 flights Sunday. Residual effects of the crowd strike update fail. This is ABC News. I'm Kareem Abdul-Jabbar. I learned about atrial fibrillation the hard way. My symptoms would come and go. Shortness of breath, fatigue. I kept going. Then I got so lightheaded, I couldn't. My doctor said I have AFib.