atrial fibrillation
"Was use by cardiologist in the hospital to correct my A-fib... but semi strenuous exercise sent me back into A-Fib a few times while on it.  Was afraid to exercise... not good. Saw another Cardiologist and he prescribe Metoprolol Succinate. This baby works like a charm, haven't been in A-fib since and am working out harder than ever."