i skipped right to get the ablations.. i think its smarter for the long run so then you dont have to worry about how the medicine can affect you long term...but im also 18 so my doctors dont want to put me on dangerous medicine..hope it helps!
Thank you! That was really, really helpful.
IST can vary greatly. Where some people just have a slightly elevated heart rate that causes no problems what so ever, some people have a far higher heart rate, and yes, a resting heart rate in the 120-130s will with time cause the heart to get an overload in pumping volume, which may cause the heart muscle to adapt in an inappropriate manner.
Just as high blood pressure (and heavy weightlifting) will make the heart walls thicken, in order to work against higher resistance, the heart will adapt to a higher cardiac output by increasing its inner space, and the heart muscle may dilate, which may with time (months, years or decades, impossible to say) cause heart failure (also known as dilated cardiomyopathy or tachycardia induced cardiomyopathy, often shortened tachycardiomyopathy).
There are other important things to remember. Often, IST is not actually caused by the sinus node, but rather another spot close to the sinus node, making the arrhythmia mimic sinus tachycardia on EKG, and in those cases the diagnosis is atrial tachycardia, not sinus tachycardia. Also, all "appropriate" causes of sinus tachycardia must be eliminated.
People with IST often struggle with low blood pressure, so beta blockers (especially the selective ones) may cause dizziness. Non-selective beta blockers can be more effective (I'm not a doctor, so what I say is strictly generally spoken and not related to your case). Another alternative is a selective sinus node inhibitor; ivabradine. It doesn't affect other parts of the heart than the sinus node.
IST can be caused both by cardiac abnormalities and abnormalities (dysregulation) in the autonomic nerve system, such as low tension in the blood vessels. An ultrasound of the heart may be appropriate to determine of your cardiac function is OK or the heart races to compensate, and to determine if your heart has suffered any damage from the rapid heart rate.
Ablations for IST are fairly new and the effect may go away, or the sinus node can be destroyed which puts someone in need of a pacemaker (which is actually not much of a crisis, by the way, and it is an alternative anyway if everything else should fail).
In my country, beta blockers or ivabradine is standard treatment for IST. I don't think they do sinus node modification (ablation). But an EP study will determine if the cause is in the sinus node or not. If you actually have an atrial tachycardia, treatment is fairly easy I think.
Good luck :)