How does supraventricular tachycardia or medication for it affect your voice?

It shouldn't. However, it is hard to know for sure without more details. Most medications don't affect the voice, but there are many things which can impact the voice. See your local ENT or laryngologist for a full evaluation of your voice. Regardless of the cause, many vocal disorders can be improved with treatment of some kind.
They don't. In general, they don't. What kind of voice problem are you having and what medicines are you taking?(it's easier to answer if we have some specifics.).

Related Questions

How can supraventricular tachycardia be treaated with medication?

Various med. Meds for svt fall into 2 major categories: those that slow conduction through the av node (beta blockers and calcium channel blockers) and anti-arrhythmics that alter ion currents such as flecainide, Propafenone and others. The first group is cheap and has no dangerous side-effects. The second group is expensive and has the potential for serious side-effects in some people. Read more...
Electrical behavior. Depending on what type of supraventricular tachycardia (svt) you have and whether treatment is chronic (every day prevention) or on an emergency basis, medication is available that either works by slowing down you heart rate overall or interferes with the transmission of electricity between your heart's upper and lower chambers thereby braking the cycle that allows svt. Read more...

Are there any other medications apart from ß-blockers that can treat supraventricular tachycardia?

SVT. Yes, there are other drugs that can treat SVT. Calcium Channel Blockers and a cardiac glycoside called Digoxin can be used to treat SVT besides beta blockers. Read more...