[1] There was nothing to separate the sides in the opening half, with Carlow recovering from an indifferent start to level matters by the break at 1-10 apiece.
Derek McNicholas rattled the net for Westmeath while Craig Doyle bagged Carlow's goal.
Robert Foley and Doyle found the net as Carlow led by ten points.
Westmeath reduced the deficit to just three points with ten minutes remaining, helped by 1-2 from star forward Brendan Murtagh.
Carlow edged further in front as full-time approached but in an amazing five minutes of stoppage time Westmeath forced extra-time with a goal from John Shaw and a last gasp converted penalty from Murtagh which ended the contest in normal time at 3-18 to 4-15.