28 y\o, i have mobitz+sinus tachycardia- blood tests, eps, stress test and eco were ok- any idea what's the cause and how dangerous it is at my age? tha

Mobitz I benign: If it is second degree av block mobitz type i, this usually reflects benign increased vagal tone causing slowed conduction through av node. It might occur after periods of sinus tachycardia or at night while asleep (increased vagal tone then also). Second degree av block mobitz type ii is more ominous and usuall implies pathological reduced av nodal conduction.