Hello, Feeling dizzy when atrial fibrillation acts up is common and for that u need to have a better rate/rhythm control medications. The choice of these medication depends upon multiple factors like Echocardiography findings, age, cause for AF among the few. As far as your blood pressure is concerned 138/110 definitely requires some change in medication. If a patient like you visits my clinic I would have taken an Electrocardiogram for your resting heart rate then decided to either increase your atenolol dosage or adding another antihypertensive drug to your regimen. Hope this clears your doubt