Just 78 points separated the top four ahead of the penultimate round in Austria but, instead of them, it was Hefti, pushed by Thomas Lamparter, who claimed the win and European title.
The 34-year-old, who is the defending World Cup champion in the two-man, was making just his fourth appearance of the season but led from start to finish for the victory in Igls.
Hefti, who won in Winterberg, was second in La Plagne and seventh last time out in Koenigssee, led by 0.03seconds after the first run before extending his winning margin to 0.10 after run two.
Defending European champion Thomas Florschuetz was second on both occasions for silver while likewise German teammate Francesco Friedrich was the third fastest on both runs for bronze.
Friedrich was just 0.02 behind Florschuetz to continue the pair's close rivalry having tied for first place at the sixth round of the season on their own ice Altenberg.
Of the top four overall heading to Igls, Oskars Melbardis placed the best in fourth with leader Rush sixth, second-placed Manuel Machata down in 13th and third-placed Steven Holcomb 14th.
Rush might now not be able to claim the newly-established and lucrative Triple Trophy, awarded if a pilot wins the final three rounds of the season, but he still leads the overall World Cup.
The Canadian had a 64-point advantage at the beginning of the round but that is now 62 from Melbardis who replaced Machata in second with the German third a further 58 back.
Meanwhile Craig Pickering's second World Cup start pushing John Jackson was worse than his first as the British pair finished two places lower than they did in Koenigssee in 21st.
After posting a start time of 5.31 they clocked 53.27 for 21st, which meant they failed to take to the ice for a second run with only those ranked in the top 20 after the first doing so.
Meanwhile the British No.2 crew of Lamin Deen and Ben Simons clocked a time just 0.05 slower than Pickering and Jackson as they placed 23rd overall in Igls.