[addy34]

Less than low energy antitachycardia pacing (LEAP), which is itself a lower-energy alternative to the typical 1-shock defibrillation. Their "1000 times less" means three orders of magnitude. From the abstract of the paper:

We find that, rather counter-intuitively, a single, properly timed, biphasic pulse can be more effective in defibrillating the tissue than low energy antitachycardia pacing (LEAP), which employs a sequence of such pulses, succeeding where the latter approach fails. Furthermore, we show that, with the help of adjoint optimization, it is possible to reduce the energy required for defibrillation even further, making it three orders of magnitude lower than that required by LEAP

Important to note that the study uses:

"an electrophysiological computer model of the heart's electrical circuits "

and

"a simple two-dimensional model of cardiac tissue"