Is avnrt or atrial tachycardia more dangerous in an athlete?

Unclear-Probably Yes. Athletic activity ?es heart rates (per brain control to ? venous return, stroke volume & rate to ? cardiac output). It thus may compound atrial tachycardia in a partially additive way. Yet, more commonly what happens is that the brain induced rate ?es simply over-ride the AVR induced rates. Best optimize NMR lipoprotens, HbA1c (best ?5.0%), get a quality echocardiogram & review images carefully!