SINGAPORE - For two weeks, he was struggling with bouts of breathlessness and chest tightness.
A doctor prescribed Mr Ooi Ka Lok, a manager in the shipping industry, medicine for what was initially diagnosed as a gastric-related problem.
When his problems persisted even with medication , Mr Ooi brushed the symptoms aside.
He never thought he would be suffering from something as serious as pulmonary embolism (PE).
PE can be fatal. It occurs when part of a blood clot that forms and blocks up a vein or artery - known as deep vein thrombosis (DVT) - breaks loose and travels in the bloodstream to block vessels in the lung.
Symptoms include an acute shortness of breath, chest pain and rapid heart rate. Some even cough out blood.
He started realising how serious it was on March 1, when he found himself gasping for air while walking up a ramp at a mall with his wife.
"I just couldn't walk any more," he said.
But when he struggled after a shower that same evening, he decided it was the last straw.
"I was struggling to breathe. It really felt like I was dying," he said.
He was admitted that night at the high-dependency ward at Gleneagles Hospital and Medical Centre.
Initially, Mr Ooi was directed to a cardiologist after his electrocardiogram showed abnormalities. An ultrasound scan also revealed that the shape of his heart was "irregular".
"Based on what I said, the doctor told me it's probably something to do with my heart or artery being choked.
"He booked the operating theatre on Monday so he could operate on me," Mr Ooi said.
But a more thorough series of scans on Sunday morning revealed the problem area was in the lungs, not the heart.
"I was shown the images from the scans, and there were many dark spots in my lungs.
"I was then referred to a respiratory specialist, who diagnosed me with massive PE," Mr Ooi said.
As he went through a battery of tests and scans one question kept repeating in his head: What could have caused the PE?
"It was hard for me to accept that I could be down with something potentially fatal. I am relatively active. I cycle and jog often. I don't smoke. My biggest sin, perhaps, is that I eat a lot," Mr Ooi said.
He added: "I have never had any major surgery before."
SURGERY INCREASES RISKS
Mr Ooi remains unclear why he was hit by PE even with no history of major surgery.
Major surgery can increase the risk of getting PE and DVT, a recent Khoo Teck Puat Hospital study showed.
For Mr Ooi treatment started on Sunday night, with an injection of 50ml of a clot-busting drug for over 5½ hours.
When he woke up on Monday morning, the ultrasound and CT (computed tomography) scans showed the "dark spots" in his lung had been reduced.
"The doctors told me that 70 to 80 per cent of the blood clot was removed. The remaining can be fixed with Xarelto, a blood-thinning oral drug," Mr Ooi said.
A month after he was first hospitalised, Mr Ooi no longer feels the discomfort and has resumed light jogging.
But he is no longer the stubborn, self-medicating person.
Not knowing the exact cause of PE means he has to remain alert.
"If I feel a fraction of what I had felt previously, I will see a specialist immediately," Mr Ooi said.
Asians also at risk of blood clots
A Khoo Teck Puat Hospital (KTPH) study has found that Asians have a similar risk to Westerners for post-surgery blood clots which get lodged in the lungs.
There is a strong misconception that Asians do not get venous thromboembolism (VTE) after a major surgery, said Dr Ong Hean-Ye, a KTPH cardiologist.
VTE is a disease process that starts with a blood clot forming in the veins, one of which is a condition known as deep vein thrombosis or DVT.
Pulmonary embolism occurs when part of the clot breaks free, travels through the bloodstream and ends up lodged in the lung artery.
The myth was debunked by a study on 1,103 KTPH patients after major operations.
A joint collaboration between KTPH, the medicine faculty at Universitas Indonesia, National University of Singapore's Yong Loo Lin School of Medicine and Temasek Foundation showed that Asians are just as likely to be diagnosed with VTE as their Western counterparts.
Twenty-three, or 2.1 per cent, of the 1,103 patients who were admitted to KTPH in 2011 and 2012 for major surgeries were found to have VTE. This is on a par with a rate of 2.2 per cent in the UK. Of the 23 patients, nine were diagnosed with PE. Three died from it.
The study also revealed that women aged above 75 who have a history of VTE and ischemic heart disease have a higher risk of getting VTE. The disease can be treated with blood thinners, with Xarelto being the latest drug to be approved by the Health Sciences Authority last December.
This article was published on April 4 in The New Paper. Get The New Paper for more stories.