Can a slow heart rate cause water retention? just looking for some answers, as i have suffered for years with this problem, and know i do have a slow heart rate, also pac which they say are benign.

Generally : Generally no, as long as your heart function, specifically both the squeezing (systolic function) and relaxing (diastolic function) are normal. If those have not been evaluated previously then you can discuss getting an echocardiogram (heart ultrasound) with your doctor. There are many things that can cause leg swelling, not just heart issues, including medication side effects and vascular issues in the legs.

By itself, no...: Your heart only needs to beet as fast as is needed to push the blood around while maintaining a proper pressure so the nutrients in the blood reach the tissues. However, if you have mild "congestive heart failure" with a such a rate, by definition you will retain fluid because the heart is not pushing the blood around fast enough to do its job. This does result in fluid retention.