What usually causes presyncope with erratic heart rate? sometimes as low as 35 and as high as 200? fatigued all the time, lightheaded, brain fog. a feeling of laziness all the time. blood pressure always low as well?

My understanding of “presyncope” is that you feel as though you are about to faint.Low heart rate and BP suggest slow heart rate and low BP as the cause. There are medications that might be contributing. You must seek help from a cardiologist who can investigate this further and help you. Do not be fearful .Make sure you see someone who has a reputation for patience and willing to answer questions