Does anyone have any ideas of what is wrong?

You still have some tests to undergo to diagnose what is wrong, the, the nocturnal bradycardia, may be the cause of your symptoms. Try not to get too anxious and think the worst as the ecg & echo have shown that the heart is in good working order, it may be an electrical heart abnormality that may not be bad enough to treat, but will be monitored or may be treated with tablets, defibrilator or pacemaker which are all routine. I know it is hard when you don't know whats wrong, but worrying won't help.

hope you are diagnosed soon.

I agree completely with Trikki Nikki, you must get some other tests done to ensure yourself that your heart is in healthy condition. Don't stress out too much so as to avoid any problems. Get well soon.

Rest assured it anything was greatly amiss with heart your tests would have shown it up.

One thought that occurs to me is a vagus nerve disorder (Google it) it can cause stomach pain by blood being diverted to the stomach, hypertension and heart rate slowing and passing out.

You may wait a long time for a tilt table test. My wife has been waiting since mid December.

What is exactly the tilt table test? Why a person has to wait so long for this?

GP told my wife that the tilt table test will not be carried out at local hospital but subcontracted to a clinic that specialises in cardiology testing.

Mostly tests seem to have long waiting times because hospitals technician and doctors are stretched to the limit leaving equipment underused. When I needed a stress echo cardiogram three years ago at local hospital I waited seventeen weeks before getting a cancellation. It turned out that they only did four a week with the equipment only being used for about six hours a week.

The head-up tilt table test is a way to find the cause of fainting spells. The test involves lying quietly on a bed and being tilted at different angles (30 to 60 degrees) for a period of time while various machines monitor your blood pressure, electrical impulses in your heart, and your oxygen level.

The head-up tilt table test is performed in a special room called the EP (electrophysiology) lab.

This seems to be very tough. It's hard to wait for so long to get tested. Is there any alternative to it? What can be done in case of emergency?

You could Google 'alternatives to tilt test'

Several articles and videos will come up.

Do you get the abdominal pain at other times without passing out?

Some years ago my wife had a late night similar incident to you without passing out. I dialled 999 and we were invaded by paramedics (about 10) they did an ecg that was OK. And took her to hospital. One of the paramedics said that when he had a similar pain it was from a duodenal ulcer. I said that it had been similar pain when I had one.

The deemed it to of cardiac origin, gave her blood thinners and tests, X-Rays and scans but found nothing. Kept in hospital overnight with my wife insisting it wasn't chest but stomach pain. She was discharged the next evening being told that a reason is never found for chest pain 50% of the time. We again insisted that it was abdominal pain without getting anywhere.

After the weekend she went to her GP. He poked her in the lower abdomen, she yelped and he said 'duodenal ulcer' She had an endoscopy that found the duodenal ulcer. They also found about 60 small gastric ulcers that had been caused by painkillers and anti inflammatories the hospital had given her a few weeks before for gout.