Tight K Trial
Research type
Research Study
Full title
The TIGHT-K STUDY. Dysrhythmias on the cardiac intensive care unit - does maintenance of high-normal serum potassium levels matter?
IRAS ID
260639
Contact name
Benjamin O'Brien
Contact email
Sponsor organisation
Bart's Health NHS Trust
Duration of Study in the UK
4 years, 5 months, 29 days
Research summary
A fast irregular heartbeat can occur after heart surgery. These may be dangerous and keep patients in hospital longer. Many doctors believe giving patients potassium helps prevent these irregular heartbeats. However, there is no scientific evidence that such treatment works. Potassium can also be unpleasant for patients to take and expose patients to additional risk.
The aim of the Tight K Trial is to investigate whether it is necessary to administer additional potassium to prevent fast irregular heartbeats after heart surgery. Maintaining potassium levels at the high end of the normal range is the current standard care for these patients.
The patients approached for this trial will be scheduled to have coronary artery bypass graft (CABG) surgery at participating NHS hospitals. Patients will be approached by a member of the research team when they attend clinic before their surgery. If they are happy to take part, they will be asked to sign a consent form at a clinic visit or when they are admitted for surgery.
Patients will be randomly allocated using a computer to a strategy of either having their potassium levels controlled as per standard care (the ‘tight’ arm) or when they drop below normal range (the ‘relaxed’ arm).
There will be no difference to the normal standard care leading up to, or during, the CABG surgery.
The trial treatment period begins upon admission to intensive care or surgery step-down ward following surgery. All patients will have their potassium levels monitored as usual. Local care teams will decide how to supplement potassium according to their normal local practice.
Patients will be monitored for episodes of irregular heartbeats. Fast irregular heartbeats are called atrial fibrillation (AF). Patients will wear a device called a holter monitor that will record their heart rhythm. It is attached to the patient’s chest using special stickers, similar to the ones used when having an ECG.
Any patient in the ‘relaxed’ arm of the trial that has an episode of AF lasting longer than 30 seconds will be treated according to standard care from that point onwards.
Following discharge, patients will be followed up by a member of the research team 6 months after their surgery.
Lay summary of study results:
Why we did the study:
One out of every three patients develop an irregular heart rhythm called atrial fibrillation (AF) in the days after heart surgery. People with atrial fibrillation are at an increased risk of stroke and other medical complications.
To prevent this from happening, many hospitals give extra potassium to patients in the days after heart surgery. Potassium is usually given to patients via a drip, or as a tablet.
Giving extra potassium is expensive and there is no evidence that it works. Tight K set out to find out whether giving extra potassium is needed.What we did:
The Tight K study recruited 1690 people having heart surgery (coronary artery bypass surgery). We did not include people having any other procedures at the same time, for example valve surgery. Patients were recruited into the trial between October 2020 and November 2023 from 23 hospitals in the UK and Germany.
The study compared two groups of patients. Both groups had the potassium levels in their blood monitored for five days after heart surgery. Half the patients received potassium only if levels of potassium in the blood dropped below the normal healthy range. This was called the Relaxed group. Half the patients received extra potassium. This was called the Tight group. The study group that patients were in was decided by chance, a process called randomisation. This is similar to flipping a coin.
What we found:There was no difference in the amount of AF in the Relaxed and Tight groups. We also found that when patients got less potassium, it saved money (£87 per patient).
Where can I learn more about the study:
The results were published in the Journal of the American Medical Association in August 2024.
https://gbr01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fclick.pstmrk.it%2F3ts%2Fjamanetwork.com%252Fjournals%252Fjama%252Ffullarticle%252F2823246%2FNBTI%2FmtK7AQ%2FAQ%2F6ca455ef-29ee-4100-8506-c17ecd4028dd%2F2%2FzqLUz1GJkW&data=05%7C02%7Cqueensquare.rec%40hra.nhs.uk%7Ca8b3f80f43784cbdfdfd08dd5cef5816%7C8e1f0acad87d4f20939e36243d574267%7C0%7C0%7C638768905215604090%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=xQdjhzaQ5RQEzfVejTbd4zS9dgFBhYidRSncRMvqK1A%3D&reserved=0The Tight K Trial was funded by the British Heart Foundation and sponsored by Barts Health NHS Trust.
URL to summary results:
https://gbr01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fclick.pstmrk.it%2F3ts%2Fclinicaltrials.gov%252Fstudy%252FNCT04053816%2FNBTI%2FmtK7AQ%2FAQ%2F6ca455ef-29ee-4100-8506-c17ecd4028dd%2F3%2FWPZ0rDETvg&data=05%7C02%7Cqueensquare.rec%40hra.nhs.uk%7Ca8b3f80f43784cbdfdfd08dd5cef5816%7C8e1f0acad87d4f20939e36243d574267%7C0%7C0%7C638768905215621207%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=OKhJfWi0dHroQFDkhSaLtAAc4AiX4y%2BxYo3f%2FpjWNpw%3D&reserved=0
REC name
London - Queen Square Research Ethics Committee
REC reference
19/LO/1064
Date of REC Opinion
16 Aug 2019
REC opinion
Further Information Favourable Opinion