My doctor told me yesterday that I have svt. Is this dangerous? My last stress test was 3 years ago. Do I need a  cardiologist  appt.?

Fast heart rate. Supreventricular tachycardia (svt) is a fast heart rate that starts in the pace-maker of the heart. It can have a number of causes and can be dangerous if it progresses to ventricular fibrillation. You should go back to your doc and discuss this further and see if they want you to see a cardiologist. This will depend on your history and current symptoms.
Depends. It depends on whether you have seen a cardiologist in the past and if there are new symptoms. If you had a cardiology consult when you had your stress test and were diagnosed with svt then they may not want to see you again unless changes develop.
Yes to both. If you have actually been diagnosed with svt by your primary doctor then you at least need to see a cardiologist to see if there is some other important underlying cause. In any case, further testing should be performed. Uncontrolled svt can be quite dangerous if you have actual coronary or heart disease to begin with that is underlying and undiagnosed.
Needs attention. Hello, svt (supra-ventricular tachycardia) is a broad term that covers many different kinds of fast heart rates originating from the top of the heart. It could be caused by a fast sinus node, conduction loop, atrial fibrillation... It is usually not very dangerous but the treatment for each is different. You should see someone fairly soon to identify the kind of svt and possible cure it.