The invention discloses an
isoquinoline compound or salt thereof shown as a formula I, wherein R1 and R2 are H, -OCH3 and -OCH2Ph or -NHSO2CH3 independently or R1 and R2 are connected into -OCH2O-; R3 is -NO2, -NH2 or -NHSO2CH3; and R4, R5, R6 and R7 are independently H, -OCH3, -NO2, -NH2 or -NHSO2CH3. The invention also discloses a preparation method of the compound, the medicinal composition containing the compound, and application of the compound in preparing medicaments for treating anti-arrhythmia. The
isoquinoline compound or salt thereof has the effect of
potassium ion channel blocker, and shows effective activity of prolonging effective
refractory period and better heart selectivity, so the
isoquinoline compound or salt thereof has better anti-arrhythmia activity.