SCN5A and familial long QT syndrome: Moreover, phosphorylation at S571 contributes in HF, but not in pressure overload hypertrophy.118 Two proarrhythmic NaV1.5 variants (A572D and Q573E) were initially identified in extensive genetic analysis of LQTS probands.119, 120, 121 Both of these variants reside near the CaMKII phosphorylation site serine 571.