Johanna Konta says she felt “lightheaded” after suffering from heart palpitations during her straight-set defeat at the Lexington Open.
Konta, seeded third on her WTA Tour return, was beaten 6-4 6-4 by world number 48 Marie Bouzkova in Kentucky.
The Briton needed medical attention early on but, after consultation with a doctor, was able to return to court.
“My heart rate shoots up for no reason,” Konta, 29, said. “I wasn’t gassing in any way in my lungs.”
She continued: “It actually goes up and stays there so it makes me a bit lightheaded – I just needed to see the doctor and the physio.
“It was very high when they came out. I was having all the checks. I am as fit as a fiddle but it can happen. It took a while to settle down but then it did and I was able to concentrate on the tennis.”
Konta had also lost to the Czech Republic’s Bouzkova in Mexico in March in her final match before the tour was suspended because of the coronavirus pandemic.
After play was delayed by four hours because of a rain storm and after surviving a break-point scare in the opening game of the match, which was played in extreme humidity, Konta appeared to be struggling with the conditions.
She has suffered similar issues in the past, notably at the 2016 US Open and at the Fed Cup last year. She recovered to win both matches.
“We don’t know why it happens: it’s been under stressful situations, in no-stress situations. We just don’t know. It’s been sporadic,” Konta said.
“It’s not ideal. I am going to have another ECG and see what protocols we can take. It’s probably not going to happen again for another year or something. I’m not too worried, no.”
British compatriot Heather Watson also made a losing return to the WTA Tour in Kentucky, beaten 6-2 6-1 by American Jennifer Brady.