They started whacking people in Australia. This is what they found:
Unsurprisingly, defibrillation was substantially more effective. Combining the data from both rhythms, precordial thump resulted in ROSC in 5/103 patients (estimated NNT of 26.2) while defibrillation led to ROSC in 188/325 (estimated NNT 1.7). More concerning, 10/103 (estimated NNH of 10.3) thumped patients shifted into rhythms with poorer prognosis (8 VT -> VF; 1 VF -> PEA; 1 VF -> Asystole).
That’s from BoringEM–all the links to the studies are on his site. Food for thought and kind of fun, if nothing else.