Were it not for the timely medical intervention, his condition would probably have deteriorated beyond recovery.

"Were it not for" 是正式语体中的倒装虚拟条件结构，相当于 "If it were not for"，引出与过去事实相反的假设条件；后接名词短语 the timely medical intervention 作为条件内容，主句用 would probably have deteriorated 表示反事实条件下的推断。