20 Pa.C.S. § 3375

If a plaintiff or petitioner in any action or proceeding now pending or hereafter brought dies and a personal representative is not appointed within one year after a suggestion of such death is filed in the action or proceeding, any defendant or respondent may petition the court to abate the action as to the cause of action of the decedent. Copies of the petition shall be served upon the executor named in the will, if known to the defendant, and otherwise upon all known next of kin entitled to letters of administration. The court shall abate the action as to the cause of action of the decedent if the delay in taking out letters is not reasonably explained.