MLB

Mets’ Niese has rough start against Yankees

In Jon Niese’s first start since suffering from an elevated heart rate, making him unable to catch his breath on the mound last Saturday in Texas, the left-hander gave the Mets a quality start.

It wasn’t his heart that troubled him in last night’s Subway Series opener, but a three-run first inning that cost him in a 5-1 loss to the Yankees at Citi Field.

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Niese says he suffers from tachycardia once or twice a month, but downplayed the issue and said he did not have any reoccurrence last night. He simply got away from his big-breaking curve and served up too many fastballs early. The Yankees made him pay by jumping out to a 3-0 lead, and though he settled in, it was too late.

“I threw too many fastballs their way, and before I could change it up the damage was done,” said Niese, whose record fell to 7-7. “I felt good. It’s tough to win games giving up three runs in the first. But I tried to battle and keep the team in the game.”

In his previous eight starts, Niese went 5-2 with a 2.36 ERA thanks to an effective curveball. But he opened the game by allowing three straight hits on fastballs, singles by Nick Swisher and Curtis Granderson and Mark Teixeira’s two-RBI double to right. He finally unleashed a curve and retired Alex Rodriguez, but Robinson Cano hit a cutter to deep left for an RBI double.

“Usually in the first inning I can get away with using only fastballs, but they put some good swings on them,” Niese said. “Those two balls hit down the line, a foot or two the other way and they would’ve been foul balls.”

After a visit to the mound from manager Terry Collins, Niese started changing speeds, and over the next five innings did not allow another run while striking out seven, many of them on curveballs.

Collins said his advice to Niese was simple.

“I basically said, ‘Pitch. Use your stuff,’ ” Collins said.

Whatever Collins said worked, as Niese caught Jorge Posada looking with the bases loaded for the second out of the sixth and induced a groundout from Swisher to end the threat. He allowed nine hits and three earned runs in six innings.

Niese suffered the tough-luck loss, but more important, he escaped the game without any health issues. He struggled to catch his breath during his start in Texas on Saturday, but he came through a battery of tests — an echocardiogram, electrocardiogram, stress test and wearing a Holter heart monitor for 24 hours — at Henry Ford Hospital in Detroit on Tuesday with a clean bill of health.

He sounded almost embarrassed when asked about his health last night.

“Oh, that was nothing, just one of those things where I had an adrenaline rush,” he said. “It’s really nothing.”

brian.lewis@nypost.com