The great Segula of reading Parshas Amaleik:^[1]

The spiritual failing known as Timtum Haleiv which manifests as clogging of the heart can be caused by sins or by the Kelipa of Amaleik. When caused by the Kelipa of Amaleik it is known as Kashyus Haleiv, hardness of the heart, versus simply a clogging of the heart. The only way to remove this is through complete nullification and by reading the Parsha of Amaleik.

[1] Sefer Mamarim 5572 page 162