Chasing a modest 124 to win the Australian side lost wickets in a heap after dismissal of skipper James Hopes, who hit a defiant 37, and now have two defeats in as many matches.
Hopes in company of Daniel Christian (21) raised a 44-run stand for the fourth wicket to stabilise the innings as they had lost three early wickets. However once the two batsmen departed, Heats wilted under pressure.
Left-hander Chris Sabburg raised their hopes with a quick-fire 19 off seven balls but his run out in the last over proved a last nail in the Heats' coffin.
Fast bowler Marchant de Lange took three wickets for 13 runs in his four-over quota to be the most successful bowler for Titans while his pace colleague Rowan Richards took two for 20.
It was Richards, who broke the crucial stand between Hopes and Christian by cleaning up the latter.
Heats required 10 runs off the last over but managed only five and lost three wickets, including two runouts.
Titans, who were invited to bat, could not even bat for their full quota of overs as they were bowled out for 123 in 18.5 overs.
Skipper Henry Davids top-scored with a 31-ball 39 and added 69 runs for the second wicket Heino Kuhn (31).
Australian paceman Matthew Gale emerged wrecker-in-chief for Heats as he took four wickets at the expense of just 10 runs in his 2.5 overs. Christian took two wickets for 16 runs.