""Beta blockers are competitive antagonists that block the receptor sites for the endogenous catecholamines epinephrine (adrenaline) and norepinephrine (noradrenaline) on adrenergic beta receptors, of the sympathetic nervous system, which mediates the fight-or-flight response."

Although they effect heart rate largely due to the above, most Beta Blockers don't change the timing of most of the components of the electrical activity as represented on the EKG. Sotalol prolongs as aspect of the EKG that can lead to other arrhythmias, most other Beta Blockers don't have that effect.

The information in my original post was paraphrased from a site on EKG interpretation. My point was that Sotalol isn't just a Beta Blocker, that under many circumstances additional precautions need to be taken with it when first putting a patient on it.

Reading it over again, I'd say the EKG Site and you are both right, just in different ways. They are talking about rhythm in the sense of the elements of the EKG, you're talking about rhythm as associated with rate. Beta Blockers do indeed alter heart rate, and many people benefit from that for various reasons.