No, it is notParoxysmal tachycardia gives you the ability to watch the ``coming and going`` of tachycardia.Unsustained tachycardia has little to no change in rhythm rate.
Inappropriate sinus tachycardia is a rapid heart rate at rest. The heart rate is more than 100 BPM. If the heart rate is more than 100 BPM less blood fills the coronary arteries so the less energy...
In any case where there is uncertainty always assume that the rhytm is v tach. One reason is that sustained v tach may be stable for a while , but tends to deteriorate into ventricular fibrillation...