A-Fib Calc The A-Fib Calc app offers a quick, accurate method of calculating the CHA2DS2-VASc score for atrial fibrillation stroke risk. CHA2DS2-VASc stroke risk grading system is an extended version of CHADS2 and includes additional stroke risk factors for patients who have been diagnosed with A-Fib. Use A-Fib Calc to calculate the CHA2DS2-VASc score and determine stroke risk in A-Fib by inputting the appropriate responses to the following criteria: - Age range in years - Sex - Congesti