NEW YORK -- Jonathon Niese insists it's not that serious.

It sounds bad, an elevated heart rate serious enough that it has now forced Niese out of three starts in his major league career. It sounds scary, when you hear catcher Anthony Recker talking about how he walked to the mound in the sixth inning Friday night and heard his pitcher say, "My heart's racing."

But Niese said Friday night that it's not that bad, and not that scary.

Jonathon Niese

#49 SP
New York Mets

2014 STATS

• GM30

• W9

• L11

• BB45

• K138

• ERA3.40

"When it happens, I know it's going to go away," he said.

It went away Friday, but not fast enough to allow Niese to continue pitching a game he had under control. He had worked 5 1/3 scoreless innings and had a low pitch count of 66, but the racing heart forced him out of a game the Mets went on to lose 3-1 to the Houston Astros.

Niese left games in 2011 and 2012 because of the same issue, and he visited several doctors then in an attempt to figure out what it was and what to do about it. He could have had a heart procedure known as ablation, but the experts at the Cleveland Clinic told him it wasn't necessary.

Niese said Friday that without undergoing the procedure, there's always a chance that he would have to deal with the issue again. He will now undergo more tests, but seemed satisfied to have gone two years without having a problem before Friday.

"Once every two years, I'll take that," he said. "It just happens. If it happened on a more regular basis, I'd probably do something about it."

Niese seemed more concerned about the strength in his left arm. He said again that while he wasn't disappointed with his season, he wants to build up his strength in hopes that his velocity returns in 2015.

The lower velocity was enough of a concern that the Mets had Niese spend time on the disabled list this season. Even with the lower velocity, though, Niese finished 2014 with a 3.40 ERA, matching the career best he set in 2012.

"I took a huge step with my changeup this year," he said. "I figured out how to pitch. Hopefully I can do some things to help my arm strength, and hopefully be able to pitch with my good stuff."

Hopefully, his heart doesn't start racing and force him out of more games. But if it happens, Niese believes it's nothing to be overly concerned about.