It is not. At least the slow lifts are too restrictive on blood flow. Fred Hatfield did claim that Olympic lifting did interesting/good things for ejection frac

It is not. At least the slow lifts are too restrictive on blood flow. Fred Hatfield did claim that Olympic lifting did interesting/good things for ejection fraction (IIRC) but these lifts have very little time under tension so are a different animal. I would suspect you were reasonably fit before, needed some more leg strength to hit your peak speed, and didn't lose too much cardio from not doing it for a month.